Alumino Thermic welding [⇐ENCYCLOPEDIA HOME]

Alumino Thermic welding [�ENCYCLOPEDIA HOME] Show pagesource | Old revisions | Backlinks Site Menu • at_welding ENCYCLOPEDIA HOME Search   Trace: » Alumino Thermic welding Alumino Thermic welding Alumino thermic welding is a process that causes fusion of metals by heating them with superheated molten metal from an alumino thermic reaction between a metal oxide and aluminium. The alumino thermic process is extensively being used world over for joining the ends of the rails. On Indian Railways Alumino thermic welding with short pre-heating process called SKV welding is used for welding of rails of different chemistry and sections. Table of Contents Alumino Thermic welding Advantages of SKV welding Principles of Thermit Welding and its Formula Thermic reaction: Process of AT welding Reference documents for Quick thermit welding with short pre-heat (SKV process) Thermit Welding Equipment and Accessories Moulds Thermit Portion Inspection of Rails before Welding Preparation of Rail Ends Gap between Rail Ends Preliminary Work Prior to Welding Alignment of Rail Ends Before Welding Fixing of Moulds Luting Preheating Maintenance of Crucible Executing of Welding. Block Period & Train Passing Time Marking of Joints Heat Affected Zone (HAZ) Frequency of In-service Painting Acceptance Tests on Welds Precautions to be taken During SKV Welding Parameters for different gaps of A.T. Welding Techniques Alumino Thermit Welding Do’s & Don’ts LATEST DEVELOPMENTS IN AT WELDING Advantages of SKV welding It is possible to do it at site under field constraints with reasonable quality. It is used to weld flash butt panels of 3 rail/ 10 rail/ 20 rail panels into long panels. Most suitable for taking up repair work of fractures and isolated welding. No pressure application is required and needs normal surface preparation compared to other types of weldings. Principles of Thermit Welding and its Formula Thermic reaction: Alumino thermic process is based on chemical reaction of iron oxide with aluminium. The reaction is ‘exothermic’ and is associated with heat* generation. After exothermic reaction lasting for few seconds, approximately equal volumes of molten steel and liquid Al 203 are separated at a temperature of about 2400 0C. Al 203 (slag), being lighter, floats on top of the molten metal. Ferro-manganese is added to the mixture together with pieces of mild steel to control exothermic reaction to match wear resistance of thermit steel to that of the http://wiki.iricen.gov.in/doku/doku.php?id=at_welding[24-12-2013 12:20:25] Alumino Thermic welding [�ENCYCLOPEDIA HOME] various grades of rail steel to be welded. Fe 203 + 2Al = Al 203 + 2Fe (25000C, 43.2 K Joules). Process of AT welding RDSO has issued a ‘Manual for Fusion Welding of Rails by the Alumino- Thermic Process’. The alumino thermic process is to apply it for joining two pieces of rail, end to end, by casting molten ‘steel’ into a refractory mould that has been placed around the spacing between the two rails. The ends of the rail must be straight and the correct welding gap established. The rails must be properly aligned with faces free of rust, dirt & grease. The rails must then be preheated sufficiently to provide conditions for complete fusion between molten steel and the base metal of rails to be welded. Prefabricated moulds are fixed and joints are filled with luting sand. The thermit reaction is carried out in a conical metallic shell lined with magnesite, called ‘crucible’, prior to tapping into the moulds. The weld must then be cooled prior to allowing any traffic hydraulic rail tensor if used during the welding. Reference documents for Quick thermit welding with short pre-heat (SKV process) The thermit welding with short pre-heat (SKV), despite all the improvements, still requires great care by the welders and supervisors during execution. For executing good quality welds, following documents should be referred to: Indian Railway Standard Specification for fusion welding of rails by Aluminothermic process (IRS-T-19-1994). Manual for fusion welding of rail joints by the alumino thermic process (Printed in Sept.1998), read with C.S.No.1 to 5. Instructions issued from time to time for improving the quality of welds and to contain weld fracture. Thermit Welding Equipment and Accessories S.No. Description Quantity Mass Welding Pre-Heating Equipment A1 Air-Petrol pre-hearing 1. Pressure tanks with pressure gauges complete Vaporisers (burner) complete Nozzles prickers Nozzle keys Vaporiser standv 2 Nos. 2 Nos. 1 No. Repair Welding 2. 3. 4. 5. 2 Nos. 4 Nos. 1 No. 1 No. 1 No. 2 Nos. 1 No. http://wiki.iricen.gov.in/doku/doku.php?id=at_welding[24-12-2013 12:20:25] Alumino Thermic welding [�ENCYCLOPEDIA HOME] 6. Goose neck attachment to vaporiser 4 Nos. 2 Nos. A2. Compressed air-petrol pre-heating 1. 2. 3. 4. 5. pressure gauges Torch (burner) complete Torch (burner) keys Torch (burner) stand Goose neck attachment to vaporiser 2 Nos. 2 Nos. 1 No. 2 Nos. 4 Nos. 1 No. 1 No. 1 No. 1 No. 2 Nos. A3. Oxy-LPG pre-heating 1. 2. 3. 4. 5. Oxy-LPG torch (burner) Oxygen cylinder with pressure gauge LPG cylinder with pressure gauge Torch (burner) stand Connecting hose pipe 2 Nos. 2 Nos. 1 No. 2 Nos. 4 Nos. 1 No. 1 No. 1 No. 1 No. 2 Nos. B Other Equipment 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. 15. 16. 17. 18. Crucible complete Crucible caps Crucible forks Crucible stands Crucible rings Mould pressure (clamp) Cleaning rod round Tapping rod Straight edge 1m long Straight edge 10cm long Aluminium steel rod for thermal plugging Leather washers for pump Gap gauges and height gauge Filler gauge Tools for punching the marking Mould shoes Stop Watches 2 Nos. 2 Nos. 2 Nos. 2 Nos. 2 Nos. 2 Sets 2 Nos. 1 No. 2 Nos. 2 Nos. 2 Nos. 4 Nos. 2 Nos. 2 Nos. 2 Sets. 6 Pairs 1 No. 1 No. 1 No. 1 No. 1 No. 1 No. 1 Set 1 No. 1 No. 1 No. 1 No. 2 Nos. 2 Nos. 1 No. 1 No. 1 Set. 2 Pairs 1 No. 1 No. Pyrometer/ thermal chalk for measurement of 1 No. rail temperature Wooden wedges for rail alignment First aid box filled with medicines,bandages, cotton etc. Mirror 150 X 100 mm with handle Tool box containing : 24 Nos. 1 No. 19. 20. 12 Nos. 1 No. 21. 22. 2 Nos. 1 No. http://wiki.iricen.gov.in/doku/doku.php?id=at_welding[24-12-2013 12:20:25] 5m above Ground to avoid ingress of moisture. 25. • Once portion absorbs moisture. shoes gear & leather gloves shall be provided 5. the same cannot be removed even by drying as ingredients react chemically. These should be stored in water tight stores kept 0. first in a polythene bag and then in a cloth bag. 26. • It should be ensured that the portion to be used must match the rail section. will have double packing. 1 No. Damaged/torn polythene bag may result in moist/damp portion and should not be used. 23. 1 No.Alumino Thermic welding [�ENCYCLOPEDIA HOME] (i) (ii) (iii) (iv) (v) (vi) (vii) (viii) (ix) (x) (xi) (xii) (xiii) Hot sets (chisels) (For emergency use only) Funnel tin (for pouring petrol) Adjustable spanner Hammer 1 kg Sledge hammer double panel 5 kg Steel wire brush Blue goggles Paint brush 50 mm Slag container (bowl) Asbestos gloves Hose clips Pliers Rail file 350 x 40 x 6 mm (For emergency use only) Weld trimmer Insulation hood for control cooling (for 110 UTS rail welding) Rail profile guided grinding trolley 2 Nos. 1 No. To ensure quality. 1 No. RDSO’s seal should be available on top of the bag.3m away from wall and 0. • The crucible cap should then be placed in position and an igniter (sparkler) hooked on to the crucible cap ready for use. 1 No. 2 Nos. • The ‘acceptance slip’ for the portion given by the RDSO shall be found inside the bag. 1 No. 1 No. • Therefore suitable storage condition for portion & mould to avoid contact from moisture is to be made. http://wiki. 1 No.php?id=at_welding[24-12-2013 12:20:25] . Storage. 24. 1 No.iricen. the portion should be heaped at the center of crucible and a small recess made at the top into which the igniter can be placed • Portion should not be mixed with any foreign material or any amount of additional portion. 2 Nos 1 No. 1 No. The portion should conform to IRS-T-19-1994. 1 No.gov. All such portions should not be used for welding. 4 Pairs 4 Nos. 2 Nos. 4 Nos. 2 Nos. protective clothing. 1 Pair 1 No. Preservation and Handling of Portions & Moulds • The portion being hygroscopic in nature. 2 Pairs 1 No.in/doku/doku. 1 No. 1 No. 1 No. • The portion should be poured into the crucible through fingers with a spraying action and striking the crucible wall so that the bottom plugging remains undisturbed • After filling. 2 Pairs 4 Nos. 1 No. grade of rail and the welding technique. 1 No. 2 Nos. (a) One random sample per batch of 300 or part there of may be drawn from the portions available in stores. © In case the reaction is found to be quiet or boiling. If reaction is normal. • Before mounting on the rail ends to be welded..Alumino Thermic welding [�ENCYCLOPEDIA HOME] • Particulars of portion contained in the acceptance slip such as Batch No. • Moulds are made by mixing high silica sand to IS: 1987 with sodium silicate to the required consistency.1. However. each pair of moulds shall be examined for defects. etc. • These prefabricated moulds shall have adequate permeability for escape of mould gases and adequate reinforcement to avoid mould crushing during transportation and welding. Shelf life of portions: • There is no specific shelf life for portions. etc. Date of Manufacture. Thermit Portion • Portion is a mixture of different materials when melted forms the material of type rail steel designed for doing one weld.2. should be recorded in a register kept for this purpose. If values obtained in the above tests are within the specified values as given in Para 4.in/doku/doku.. • Moulds shall be handled with due care to avoid any breakage. It depends on the quality of packing and storage conditions. Moulds • Only prefabricated moulds supplied by the portion manufacturer shall be used for welding.gov. • The prefabricated moulds shall be handled with care. • The suitability of the ‘ Portion ‘ for the welding process in respect of the type and section of rails to be welded shall be ensured before commencing welding. as they are fragile and liable to breakage.. (b) The sample shall be tested for reaction test.3. • Different main ingredients used in manufacture of AT portion are o Mill scales o Aluminum o Ferro-manganese http://wiki. the portion can be used even after a long time. a test joint should be made from one more sample selected from the batch for conducting Aluminium content test and Load deflection test. (e) Rejected portions are to be disposed-off by igniting five portions at a time in a pit away from the store. blocked vents. followed by passage of carbon dioxide gas. (d) The above tests should be conducted at Zonal CMT’s organization and / or the Flash Butt Welding Plant. and defective moulds discarded.1 of IRS: T-19-94. the batch represented by the sample can be used. • If packing is intact and there is no entry of moisture. dampness. • The ‘portion’ used for welding shall conform to the technical requirements as mentioned in IRS : T-19-1994.php?id=at_welding[24-12-2013 12:20:25] . otherwise batch should be rejected.3 and 4. cracks.iricen. following procedure is to be adopted for permitting use of portions. Portion No. batch represented by the sample can be used without further tests. if they need to be used beyond two years after the date of manufacturing. Kanpur.php?id=at_welding[24-12-2013 12:20:25] .iricen.gov. excessive scabbing. http://wiki. Luknow. o Rails should be free from corrosion. o If fish bolt holes are not present. • Any burrs at the rail ends shall be removed by chiseling or grinding. only 4 firms are approved for manufacturing of portions and execution of welding. o Lateral wear on rail head should not be greater than 6mm. Bilaspur. and corrugations. • In India.5mm in lateral direction with 1m straight edge. Hyderabad. • Normally. -0mm in vertical and +/_ 0. • Harshad Thermit Industries. • Sagar Electrical and General Industries. o The ends should be cropped to eliminate fish bolt holes.Alumino Thermic welding [�ENCYCLOPEDIA HOME] o Steel chips o Silicon carbide o Ferro vanadium o Flour spar • The proportion and quantity of the same depends upon the type of rail section and type of welding and is the trade secrete of the manufacturing company. no alumino-thermic welded joint shall be located closer than 4m from any other welded or fish plated joint. Preparation of Rail Ends • The rail end face and adjacent sides at foot (top and bottom).5mm. the ends should preferably be cropped for a minimum of distance150mm. grease and rust before welding. Railway. o Rails should be got tested with USFD. o Rails should be match-marked to match the rail ends for welding. They are • India Thermit Corporation Ltd. • Only RDSO certified/passed portions should be used for welding.in/doku/doku. • The new rails/ Old rails to be welded shall conform to the tolerances specified in Table 1 and Table 2 of “Manual for thermit welding” • Old rails : o Rails older than 50 years should not be welded. o Rails should be cut using sawing/ abrasive rail cutter only.. Raipur. N. though many labour contracting firms are approved by RDSO for executing AT welding with portion and technique developed by Thermit Portion Plant. Inspection of Rails before Welding • It should be ensured that the end bends of rails are within +0. web and head up to 50mm shall be thoroughly cleaned using kerosene oil and brushing with wire brush to remove all dirt. wheel burns. • Raybon Metals Private Limited. In LWR/CWR territory.6mm. Preliminary Work Prior to Welding http://wiki. • The uniformity and verticality of the gap shall be measured by a gauge prior to welding.iricen. hydraulic / mechanical rail tensor of suitable and approved design should be used for maintaining correct rail gap during welding.gov.in/doku/doku. • The gap is measured at four corners of rail section. • The permissible tolerance in squareness of joint is 0.Alumino Thermic welding [�ENCYCLOPEDIA HOME] Gap between Rail Ends • The two rail ends to be welded shall be held in position with a uniform vertical gap of 25mm+/-1mm for normal welding and a wide gap of 50±1/75±1 mm for repairing fractured/defective welds.php?id=at_welding[24-12-2013 12:20:25] . in/doku/doku. if the length of unsupported rail is more during welding. This shall be achieved by wedges applied on the rail supporting blocks on both sides of the joint. The stresses reduce. full rail length shall be leveled by supporting on at least ten wooden blocks on either side.4 mm for higher UTS rails when measured at the end of 1 m straight edge ( as a compensation against sagging caused by differential shrinkage on cooling).Alumino Thermic welding [�ENCYCLOPEDIA HOME] • Internal stresses will develop during in-situ welding as all the sleepers and rails are fastened tightly and will not allow to expand freely on rising of temperature.iricen. If excessive longitudinal movement occurs during pre-heating and produces a welding gap outside the prescribed limits. Any difference in the widths of rail heads shall always be fully kept on the non gauge side. the welding of joint shall be temporarily abandoned and joint allowed to cool.0 m straight edge at rail ends. Datum marks shall be made on foot of both rails as well as on joint sleepers in order to observe any longitudinal movement of rails. etc.5 mm when checked with a 1. clamps. • The rails shall then be properly aligned in horizontal and vertical direction and held in position. after alignment shall be within ± 0. • Therefore in case of in-situ welding rail fastenings for at least five sleepers on either side of the proposed weld shall be removed.preheating equipment. Fixing of Moulds • It shall be ensured that the center of the rail gap coincides with the center line of the http://wiki..gov. • Gap between rail ends may be rechecked after completion of alignment. • When the welding work is carried out on cess. correctly aligning the rail ends on the gauge face. • Vertical alignment : The joint shall be kept higher by 3 to 4 mm for 72 UTS rails and 2 to 2.php?id=at_welding[24-12-2013 12:20:25] . • Sleepers adjacent to the joint to be welded shall be shifted to obtain a clear working space of 250mm on either side to accommodate moulds. Alignment of Rail Ends Before Welding • Lateral alignment: The two rail ends. • After fixing the moulds. • The mould jackets/shoes hold the pre-fabricated mould in a snug fit condition by tightening with adequate pressure. • The moulds should touch the bottom of rail foot to ensure proper size of collar at the bottom. the gap between mould and the rail shall be packed firmly with luting sand to prevent leakage of liquid weld metal.in/doku/doku. Luting • It is the process of sealing the gaps of moulds. Excessive pressure may cause breakage of mould and dropping of sand inside the mould cavity.gov. • Improper luting may result in leakage of weld metal. a luting cover may be placed over mould aperture. • After fixing of the mould shoes. It may lead to formation of a ‘fin’ at the underside of flange which may lead to development of half moon crack under repetitive loading and may cause failure of the weld. luting of the junction of the mould should be done. the adjacent rail surface on either side of the moulds shall be covered with metal cover or smeared with luting sand up to 15cm on either side of the moulds.php?id=at_welding[24-12-2013 12:20:25] . http://wiki. starting from the underside of the rail foot and continuing on both sides towards the head of the rail.iricen. • To avoid any sand particle dropping into the mould.Alumino Thermic welding [�ENCYCLOPEDIA HOME] mould to avoid cross joint. • To protect the rail table from metal splashes during reaction. The material used is called luting sand. • It is essential for the moulds to fit flush to each other across the bottom of the rail flange which can be checked by feeling with fingers across the junction of the two halves of the moulds and by looking down the riser aperture. • Luting sand with minimum moisture content (6%) supplied for this purpose only should be used. so as to achieve a temperature of around 600±20 0C.php?id=at_welding[24-12-2013 12:20:25] . In the event this happens. • The burner shall be properly adjusted during preheating to ensure that the head. on Indian Railways air-petrol mixture. Higher temperature will cause metallurgical transformation and therefore should be avoided.0 kg Preheating Process of pre heating • Pre-heating is done to remove moisture from surface of rails using torches. compressed air petrol mixture and Oxy-LPG are being used requiring about 10.iricen. welding should be stopped.in/doku/doku. 4-6 min & 1-2 min. • The rail ends shall be uniformly pre-heated throughout the rail section with specially designed air petrol/ compressed air petrol/oxygen-LPG burner. • Recommended pressure should be ensured while pre-heating • Proper pre-heating of the rail ends consists of fulfilling three requirements namely: 14. a fairly usual occurrence may be the breakage of the mould. This is where a piece of the mould may break off and fall into the weld cavity.Alumino Thermic welding [�ENCYCLOPEDIA HOME] Per weld consumption of luting sand is 3. • Positioning of the pre-heating torch in the mould box must be carefully adjusted because it affects the quality of pre-heating. • The pre-heating torches should not be bent or damaged or their holes blocked. iii) Observation of the entire preheating process to ensure that rail end(s) is not melted and there is no breakage of the mould. web and foot of both the rail ends are heated uniformly to the desired rail temperature. the weld must not be executed.gov. the mould should be removed & http://wiki. • Rail ends and moulds must heat evenly. Uneven heat can cause internal cracking of the weld due to uneven cooling. • Presently. • The pre-heating shall be done from the top of the mould box for stipulated period for welding technique adopted.12min.5 to 4. In the event a portion of the rail head or rail face of either rail end is melted.1 Minimum pre-heat time ii) Achieving proper and the uniform colour of the rail ends. • During the preheating process. if necessary. oxygen supply should be stopped first followed by LPG supply. pressure for oxygen and LPG cylinders shall be adjusted in the range of 7.iricen. • Slag should be cleared from the crucible side walls after each weld. or relining as necessary http://wiki. While closing. 14. • Preheating Pressure: 7±0.gov.0 kg/ cm2 and 2. • Preheating should be done from top to bottom. During cleaning.3 Preheating time & pressure • Preheating time: Preheating time would be about 10 to 12 minutes and 2 to 2.5 minutes for air-petrol and oxy-LPG preheating techniques respectively. While preheating with oxy LPG burner. care shall be taken not to damage the refractory crucible lining. LPG supply should be opened first. Slag shall be cleaned from the crucible after each reaction. o a defective AT weld that is full of porosity.2 Pre heating equipment Air Petrol Burner Compressed Air petrol blower Oxy-LPG heating system 14.php?id=at_welding[24-12-2013 12:20:25] . • The lining shall be examined regularly and patch repairing .0 – 8.5 kg/ cm2 respectively. • Failure to properly dry the crucible may cause. o danger of hot steel splashing forcefully out of the crucible causing serious personal injury. Maintenance of Crucible • The crucible lines with refractory material should be preheated from inside to remove moisture with the preheating torch before making the first weld.Alumino Thermic welding [�ENCYCLOPEDIA HOME] disposed off properly and new mould installed.in/doku/doku.0-2.70 kg/cm2 in welding process using air petrol burner In case of pre heating by oxy – LPG process.ignited and thereafter oxygen supply should be opened. contact type pyrometer or temperature indicating crayons may be used for measuring rail end temperature. • Control over heating time: By stop watch or by temperature measuring devices like optical pyrometer. due to a bypass of the thimble or in the event the thimble being cracked. care being taken not to disturb the tapping pin. Executing of Welding. the head of which should be covered with asbestos pulp and alumina slag. Tapping time is very important for the final weld quality.in/doku/doku. The crucible should be located in a proper position such that the tapping hole is central to the pouring gate of the mould and at a height of 50mm from the top of the pouring gate. • The optimum tapping time is 20-23 sec which is Reaction time + Waiting time( For http://wiki. causes loss of heat from the molten metal with the risk of lack of fusion. o cause premature tapping of the molten weld metal. about 5 seconds should be allowed for separation of the slag from the metal. The crucible should not move during tapping and no turbulence should occur while pouring. • Delayed tapping. While cleansing it with a thimble drift. 16. specific for the process. Thimbles with enlarged orifice should be replaced. • Proper seating of the thimble is very important. • Welding staff shall wear welding gloves and welding goggles. • Off center pours will cause defective welds due to slag inclusion. • In case of occurrence of boiling or vigorous reaction. • The crucible is then swung into position centrally above the sand core. the metal should be tapped outside and not in the mould. the preheating torch is removed and the dried sand core placed in the central pouring apparatus of the mould. all welding staff must stand clear. on the other hand. Improper seating of the thimble or application of the plugging material may. • The molten metal is then tapped into the mould by pushing up the closing pin’s shank with the tool provided for the purpose. from the time the portion is ignited. • The crucible cap is removed.2 Tapping time • Tapping time is defined as the total time.1 Ignition and reaction • After the pre-heating. • After adjustment of the crucible to obtain correct pouring position. • After the reaction subsides. care should be taken not to damage the orifice of the thimble.gov.iricen. Inaccuracies in these are likely to result in turbulent flow of molten metal. because of moisture content in the portion or crucible. the crucible should be swung clear of the moulds for charging. • The pouring gate with thimble is designed to have a precise diameter. o prevent the molten weld metal from tapping into the moulds. • The crucible should be placed on the crucible fork fixed to swivel stand on a universal mounting. • During the initial violent phase of the reaction. • The tap hole in the crucible should then be covered with a closing pin. 16. • Premature tapping can cause a high aluminium content in the weld metal with possibility of slag inclusion too. till the molten weld metal begins to pour into the mould cavity. This heat seal enables the welder to tap the molten metal at the precise time he desires. The portion in the crucible is then ignited using sparkler by placing the igniter slowly and firmly into the center of portion & crucible cap replaced.Alumino Thermic welding [�ENCYCLOPEDIA HOME] shall be carried out.php?id=at_welding[24-12-2013 12:20:25] . 16.php?id=at_welding[24-12-2013 12:20:25] . manual chipping should be done. 16. • During the trimming operation. • It depends upon the rail section and ambient temperature. mould from the top and sides is removed leaving at least 1mm excess metal on the rail table for removal during final grinding. it shall be ensured that the wedges used in aligning are in their proper places without loosening. • In the eventuality of sudden failure of weld trimmer. • The mould shoes shall be removed just prior to completion of mould waiting time.4 Chipping of weld metal • On completion of pouring. • The runner and riser must not be removed until cold. if it is not possible to use weld trimmer due to flow of metal at rail head. • With the use of hydraulic weld trimmer. the trimming should be done by using weld trimmer of suitable and approved design without knocking out the mould. the crucible is lifted off and slag bowls removed from the mould shoes. manual chipping may be resorted to. • The mould waiting time is generally 4-6 minutes for 25 mm gap joints and 12 minutes for 75 mm gap joints. and that too only by knocking towards the rail. • In case of welding of old rails.iricen.gov. • After the mould waiting time has elapsed. and they are not removed for a t least 20 minutes after stripping.3 Mould waiting time • It is the time the molten metal shall be allowed to cool and solidify after pouring with mould intact for the stipulated time. http://wiki.in/doku/doku.Alumino Thermic welding [�ENCYCLOPEDIA HOME] slag to rise on molten metal). 6 Grinding • Finish grinding of rail top and sides should be carried out by profile grinders.in/doku/doku.5 Importance of risers • The side holes of the moulds are called risers. • The risers are basically designed to allow slower rate of cooling of the weld metal to form Pearlitic structure ( fine grained with high fractured toughness) • Lower UTS rails are less susceptible to heat than higher UTS rails.Alumino Thermic welding [�ENCYCLOPEDIA HOME] HYDRAULIC WELD TRIMMER 16. only light pressure should be applied and grinding wheel should be moved to and fro to avoid local over heating. Slag comes out from this.gov. • The best finish grinding on the running surface of the rail head can be achieved when http://wiki. lower UTS rails form a better joint 16. The accuracy of grinding shall be checked by using 10 cm straight edge. • Grinding should commence only after removing the wedge kept for joint alignment and putting back the fastenings.php?id=at_welding[24-12-2013 12:20:25] . • While grinding. hence for the same welding type. • Use of hand files should not be resorted to.iricen. • Final grinding should be done to the original profile of the rail as per the dimensional tolerances prescribed in the Manual on Fusion Welding of Rails. immediate arrangements to adequately cover the site shall be made.iricen.1 Block period • Minimum block period required for doing SKV weld is 75 mints.2 Train passing time: • The first train should be allowed to pass on the newly welded joint only after 30 minutes have elapsed since pouring of weld metal.gov.Alumino Thermic welding [�ENCYCLOPEDIA HOME] the weld has completely cooled to ambient temperature. In case. Necessary speed restriction shall http://wiki. • No welding shall be carried out if it is raining.php?id=at_welding[24-12-2013 12:20:25] . the rains start while the joint is under execution. PROFILE GRINDING Block Period & Train Passing Time 17. 17.in/doku/doku. • Once in a year in corrosion areas. • On conditional basis in areas prone to severe corrosion.1 Visual inspection • All the welded joints shall be examined carefully to detect any visible defect like http://wiki. it shall be numbered 89. Frequency of In-service Painting • Once in 4 years in areas not prone to corrosion. • For Wide gap welding Fusion zone = gap/2 +32mm and HAZ = Gap/2 +42mm. And the one beyond 100mm is considered as rail failure. • Painting of weld collar should be done on all welds to protect them against corrosion immediately after the welding. Heat Affected Zone (HAZ) • It is the length of rail affected by fusion from center line of weld. • For normal SKV welding of 25mm+/-1mm.gov.3 Precautions for newly welded joints: • Before the passage of traffic. For example. year. • The newly weld need to be tested by USFD at the earliest • Till tested as good by USFD. Normally a failure occurred with in 100mm from center line of weld is considered as weld failure. the last thermit weld umber in a particular kilometer was 88 and subsequently a thermit weld has been executed. • No holes should be within HAZ. the wedges used for aligning should be removed and joint sleepers which were shifted to obtain the clear gap of 250mm on either side shall be re-shifted to the original location and repacked. The fusion Zone is 45mm and the HAZ is 55mm. agency. • Repair welds/additional welds done at a later date may be given continuing weld number in that kilometer. 17.php?id=at_welding[24-12-2013 12:20:25] . Marking of Joints • Each joint shall have a distinctive mark indicating month. • PWI shall maintain ‘Thermit Weld Register’ as per program given in Annexure 5 of Thermit welding manual.iricen. the weld done in situ shall be joggle fish plated with two clamps.Alumino Thermic welding [�ENCYCLOPEDIA HOME] be observed until the grinding operation is over. Acceptance Tests on Welds 21. • This should be done by punching on an aluminium strip of suitable thickness and dimension of 30 X 100 mm which should be fixed to the web of the rail with epoxy adhesive at approximately 300 mm from the joint. • Fixing of Responsibility for failure of weld is based on the HAZ. • No punch marking should be done on the rail. welder’s code and weld number of the welded joint. • The welded joints shall be serially numbered in a kilometer. irrespective of its location in that kilometer.in/doku/doku. Welding – Defects.3mm over gauge side of the rail head measured at the center of 10cm straight edge.Lucknow • A welding supervisor shall supervise not more than two welding teams deployed within 50m distance at a time.iricen. blow holes.6 Guarantee • Rail joints welded by a firm shall be guaranteed against failure for a period of two years and if fails within the guarantee period shall be rewelded free of cost by the firm. • If the sample test joint fails to satisfy any of the requirements of specification two more randomly selected joints from the same lot of 100 joints shall be subjected to retests and both the joints should clear the tests.T.Alumino Thermic welding [�ENCYCLOPEDIA HOME] cracks. by the firm. which shows any visible defect should be rejected. • In case of failure of sample test joint. (iii) Finishing of top surface : +0. -0 mm measured at the end of one metre straight edge.in/doku/doku. 21. free of cost.2 Dimensional check: • All finished joints shall be checked for dimensional tolerances which should be within the tolerances.gov. Any joint found not conforming to the above stipulations shall be cut and rewelded. • If this report is also not satisfactory. further welding of joints shall be suspended until the firm’s welding technique has been examined certified by RDSO.0 mm. (ii) Lateral alignment : Variation not more that +0. etc. 21.4mm. Any joint.4 Rewelding of defective joints • The details of geometry of each joint shall be jointly signed by the firm’s and Railway’s representative and kept as record. • Where one bad joint is required to be replaced by two new joints.T. Causes & Remedial Measures ==== • The major types of defects which can cause weld failure because of improper weld http://wiki. 21. (iv) Head finishing on sides : +0. • Subsequently USFD testing of A.3 Ultrasonic flaw detection test : • All the fusion welded joints shall be ultrasonically tested and accepted by the purchaser or his representative as per the ‘Procedure for ultrasonic testing of thermit welded rail. • A copy of the thermit welding manual shall be available with each PWI and at each welding site ==== A.5 Sample testing of joints • One out of every 100 joints welded shall be selected at random and should be got tested within one month of welding for its hardness. the period of guarantee for 100 joints represented by the sample joint shall be extended for a further period of one year • The welded joints with the extended period of guarantee shall be marked ‘X’ with yellow paint on the outer side of the web of the rail near the joint 21.5 mm measured at center of one metre straight edge.php?id=at_welding[24-12-2013 12:20:25] . 21. the entire cost of both the joints hall be borne by the firm 21. transverse load/deflection tests and porosity.7 Other requirements • Welding shall be supervised by trained welding supervisor and carried out by trained welder having valid competency certificate from RDSO/TPP/NR. welds shall be done as per the provisions given in Manual for Ultrasonic Testing of Rails and Welds (1998). (i) Vertical alignment : Variation not more that +1. -0mm measured at the end of 10cm straight edge. Sand Dropping of inclusion in luting sand into the rail foot the mould. Longitudinal Cutting of wear crack in rail resistant grade web rails by flame cutting. Porosity in the thermit steel Luting sand too wet. detrimental to thermit reaction and results in gross porosity of http://wiki. Gross lack Standard mould of fusion on fitted to rails of rail end. Use of damp Carefully dry out the crucible lining crucible is using the preheating burner. Reason Remarks Flame cutting of rail ends is prohibited due to likelihood of cracking in web. the vertical. Gross porosity throughout the whole weld section.gov. with standard mould. It must not be allowed to drop into the mould. Cold spot – Mould fitted lack of vertically but off fusion and associated local porosity. Take care when sealing the mould with sand. S Location No 1. Do not try to weld worn to new rail. dissimilar depth. rail ends outside the collar formation. 2. gap. Do not incline but inclined to mould to the vertical.php?id=at_welding[24-12-2013 12:20:25] . Luting sand must be moist but not too wet. Maintain the welding gap between rail ends specified in the approved parameters of the technique. Mould fitted Take care to fit mould both vertical and center to the gap central to the weld gap. 8. or rails dissimilar depth with standard mould. centre to the web simultaneously. never flame cut rail ends 3.Alumino Thermic welding [�ENCYCLOPEDIA HOME] execution are given under. 9. 5. Never attempt to weld a gap. When producing the welding gap. Take care to centralize the mould to the gap. 7.in/doku/doku. Lack of fusion on foot of one rail end. which is too wide. Never use wet luting sand. and sand burn marks transversely across the rail head. Never try to fit both mould halves 4. Lack of Flame cutting of fusion in rail rail ends foot Cold spot – Gap between rail lack of ends too widefusion.iricen. 6. 13. This change cannot be reversed by drying out. 12. It is essential only to use dry thermit portions. Cracking of weld after cooling at rail ends. weld metal cause internal tearing of weld metal which leads to total transverse fracture. After preheating.Alumino Thermic welding [�ENCYCLOPEDIA HOME] weld metal. fit the sand core with the riser aperture of the mould and press down lightly. Moisture present in portion reacts with aluminium and in its characteristic. Failure to use the correct thermit portion and welds. (ii) Rail ends should be square. which have been damped and dried out. the following precautions shall be observed: (i) It should be ensured that the portion being used matches with type and chemistry of rail.iricen.gov. http://wiki. (iv) Rail ends should be properly cleaned with kerosene oil and wire brushes. Fracture Immediate During solidification and immediately through imposition of after thermit weld should not be weld centre.in/doku/doku. Use of damp portion. one side. Gross porosity throughout the whole weld section. rail head. Precautions to be taken During SKV Welding While carrying out welding at site. Never allow the thermit steel to pour directly into either pouring gate. Ensure that the crucible is positioned centrally over the sand core and the crucible does not move during the thermit reaction. 10. Gross slag Pouring off inclusion in centre to the rail head on plug. Never use portions. (v) Stop watch should be provided to the welding supervisor at each welding site. 11. Gross Pouring without inclusion of the plug in the slag in the position. tensile forces on subjected to tensile force. (iii) Alignment of rail ends should be perfect as checked by straight edge. Always check the chemistry and type of rail to be welded and use correct type of portion and adopt correct welding parameters at the time of welding of rail joints. Procedure as approved for specific rail section/rail chemistry. there by affecting the thermit reaction and resultant steel.php?id=at_welding[24-12-2013 12:20:25] . 14. (xvi) No moist portion/torned portion bag shall be used for welding.oil before welding to remove dust. For doing cess welding. very little skill is required to produce good cut. The rail ends should be cleaned with K.T. (xiii) Arrangements for giving first aid shall be available at site.iricen.Alumino Thermic welding [�ENCYCLOPEDIA HOME] (vi) Pressure in the tanks/cylinder should be properly maintained during preheating. (xiv) Welders should be provided with gloves and coloured glasses.e.in/doku/doku. (xii) The tapping shall be done within the time specified for that particular technique. (xvii) Dampness in moulds can lead to Porosity and early fatigue failure of welds. combination joint. (xv) Boiling portion shall be out tapped. (vii) Correct gap between rail ends at head. The evenness and verticality of a rail cut depends solely upon the skill of the welder.php?id=at_welding[24-12-2013 12:20:25] . etc. but not on the ballast shoulders. Dry moulds should be fixed centrally on the joint. 75mm gap. (xix) Many weld failures show evidence of badly cut rail ends. Fittings for a minimum of 5 sleepers on either side are to be removed for alignment and levelling.1 Do’s Welding is to be done only in adequate traffic block. Mould shoe should match with dry moulds. Supply of portions must be from sources approved by RDSO/Railway Board. Battered / hogged rails are to be end cropped before welding.gov. (25mm/50mm/75mm) Rails are to be properly aligned before taking up welding. For special type of welding i. web and foot shall be ensured. Welding is to be done either insitu or on the cess. (xi) The compressor tank shall be kept at least 2 to 3 m away from the burner to prevent fire hazard.1. (ix) Tightness of clips fitted with hose connections to compressor tank and burner shall be checked before commencing preheating. Welding Techniques 24. With portable disc cutters. grease particles. Parameters for different gaps of A. http://wiki. (viii) Correct preheating time for rail ends shall be ensured. (x) Nozzles of burners shall be cleaned periodically to avoid back – fire. the time of reaction and tapping shall be as stipulated by RDSO for that particular welding technique. Welding parameters for techniques presently being used are available at Item No. (xviii)Only those contractual agencies which have clearance from the RDSO/Railway Board can execute welding work. Moulds utilized for welding should not be cracked or wet. Welding gaps should be as specified for that type of welding. Rail ends should be cut true to square. rail should be supported on a minimum of 10 wooden blocks duly pegging the rail for better alignment. Dimensional Tolerances for finished AT Welds Alumino Thermit Welding .Do’s & Don’ts 25. 24 below. Location where portions are stocked should not be damp/wet.Alumino Thermic welding [�ENCYCLOPEDIA HOME] Rail ends are to be pre-heated uniformly Crucible should be charged with magnesite powder at regular intervals of 8-10 weld joints. should not be done without end cropping. The distance between two welds should not be less than 4 mts. particulars of welding like date of welding. Welding old rails. 25. Cap should be placed on the crucible when the reaction is in progress.. Portions should be thoroughly mixed for uniformly in a steel Pan before pouring in the crucible. Damaged dry moulds should not be used for welding. Weld portions and luting sand should not be utilized after expiry date. 72 UTS portions should not be utilized for 90 UTS rails.gov. The crucible should be free of moisture and charging should be done periodically.oil and wire brush. Worn out and damaged tools. Do not use untested rails for welding.are to be printed on aluminium strip glued to web of rail. The first train should be passed with restricted speed only after 30 minutes of welding duly grinding the weld.iricen. type of welding. so that the discharge falls centrally on the cake. The height between the crucible and dry mould should be approximately 50mm. Welding should not be done in rain or rapidly cooling temperature.in/doku/doku. http://wiki. Gauges of the pressure tanks should be functional to develop proper pressure as specified Adequate tank pressure should be maintained. On completion of the welding. equipment should not be used for welding. Chipping of weld should be done after maintaining cooling time of 4-6 minutes for a 25mm gap welding and 12 minutes for 75mm gap welding. Tapping should be done centrally in the mould. Ensure that weld portion bags are intact and portions are not contaminated. beyond which portions should be tested for reaction before utilization.2 Don’ts * Do not do welding in inadequate traffic block. Rail ends should not be welded without cleaning with K. Gas cut rails should not be used for welding. welder’s code etc. Stipulated pre heating time is to be ensured. No bolt hole should be within 40mm from the rail end. Anti corrosive painting should be done for a length of 10 cm on either side of weld. Unqualified welders should not be employed for welding.php?id=at_welding[24-12-2013 12:20:25] . The shell life of portions is 2 years. Portions should not be tampered with. It should be ensured that chisel marks are not made on the finished welds. Finishing of weld to be done within 24 hours after welding. Damaged and loose portions should not be utilized. fish plating and supporting the rail on wedges. where rail cutting is to be done by Hacksaw Blade. to complete the work early. To minimize the traffic block requirements.Alumino Thermic welding [�ENCYCLOPEDIA HOME] Luting sand should not be mixed with ordinary local sand in case of shortage. the following further instructions are issued regarding the management of traffic blocks for immediate compliance. from SEs/P.W. The work of repair of rail fractures and weld failures including the cutting of rails shall be carried out under traffic block only. Portions should not be utilized without proper mixing prior to welding. The removal of caution due to rail /weld failures will normally require two cuts an two welds after inserting the rail of suitable length (not less than 4 meters). 1. 5. traffic block of 100 minutes only shall be demanded and granted for repair of fractures involving 2 cuts and 2 welds.in/doku/doku. 2.Way of adjacent sections shall be pooled up and deployed. The first train should not be allowed over the welds before 30 minutes after the molten steel poured in to mould Speed restriction should not be relaxed till grinding of weld is completed. Wedges under the rail should not be removed for a minimum of 20 minutes after chipping.XIII. traffic block of 120 minutes shall be demanded and granted for repair of fractures involving 2 cuts and 2 welds. Wherever Abrasive Disc Cutters have been deployed. With a view to streamline the procedure for removal of cautions due to rail / weld failures. Divisions shall make efforts to procure and deploy abrasive rail cutters in all sections.gov. No deviations are permitted under any circumstances. When situation warrants due to more cautions on account of rail / weld failures. Abrasive Disc Cutters. 4. it has also been instructed to replace hacksaw blades by Abrasive Disc Cutters on priority and with due urgency. LATEST DEVELOPMENTS IN AT WELDING AT WELDING WITH THREE PIECE MOULDS COMPRESSED AIR PETROL PREHEATING SYSTEM COMBINATION JOINT & DIFFERENT GRADE RAILS WIDE GAP (50mm. the same http://wiki. Rail tensor should not be used for distressing before weld cools down. the block requirement shall be 120 minutes. In case of non-availability of continuous block of 120 minutes duration. In case the rail cutting is done by hacksaw blades. On other sections. 3. Date: 20-8-2009 JOINT ENGINEERING AND OPERATING CIRCULAR Sub: Traffic Block for removal of cautions due to Rail / Weld failures and cutting of rails. The traffic block requirement involving two cuts and two welds shall be 100 minutes where the rail cutting is done by Abrasive Disc Cutters.php?id=at_welding[24-12-2013 12:20:25] .T-5/P/Vol. 75mm) WELDING ONE SHOT CRUCIBLE SELF TAPPING THIMBLE Circulars Copy of SC Rly Headquarters letter No. 7. 6. Instructions have already been issued by Engineering Department regarding carryout repair of rail fractures and weld failures including the cutting of rails under Traffic Block only.iricen. 7/15. 6. temporary / permanent repairs of rail /weld failures shall be undertaken under traffic block only.5 dt.Railway Sub: Repairs to rail / weld failures and cutting of rails on running lines.C.XIII. 8. The work of repair of rail fractures and weld failures including the cutting of running rail shall be carried out under traffic block only. Till such time necessary speed restriction shall be imposed duly posting a watchman. It is pointed out that the work of cutting of rails is an integral part of rail renewal activity and is therefore required to be executed under clear block protection. due regard shall be given to the prevailing temperature at the time of second block. In case of rail cutting by Abrasive Disc Cutters. To avoid such unsafe situation. which is an unsafe practice. Board lr. In case of non-availability of continuous block of 120 minutes duration. the gas cut rail shall be treated as IMR rail and same will be removed within 24 hours at first opportunity. 9. No deviations are permitted under any circumstances. At times. 8. 7. It has come to notice that the work of rail cutting prior to rail renewal is being undertaken in between the train gaps with banner flag and caution order protection without ensuring traffic block.DEN/Co-ordinations of S. In case of split block f (30+90) minutes.08. No.(Pradeep Kumar) Chief Operating Manager Principal Chief Engineer. following instructions are issued on the subject matter for strict compliance in the field with immediate effect.98 that track works leading to discontinuity in track such as causal renewal of rails. 3. the same may be split in two parts. There instructions should be quickly percolated to all the officers and inspectors of Operating and Engineering Departments in control offices as well as in the field. hacksaw blades are replaced by the Abrasive Disc Cutters.2009 addressed to All Sr. Gas cutting shall not be carried out on running rails.php?id=at_welding[24-12-2013 12:20:25] . Chapter XV of G&SR-2008 and also Rly.Alumino Thermic welding [�ENCYCLOPEDIA HOME] may split in two parts i. Cutting of running rail on running lines should be undertaken under Traffic Block only.98/CE-II/INSPN. To minimize the traffic block requirements.. Block requirement for works involving one cut and one weld shall be suitably reduced. The fundamental requirements being 70 minutes block for a single weld only. Instructions exist vide para -15.iricen. 90 minutes block for two contiguous welds. a block of 30 minutes for cutting followed by another block of 90 minutes duration for welding. 5. such situations have resulted into derailments also. on priority and with due urgency.T-5/P/Vol.8. 5 minutes for a single cut by Abrasive Disc Cutters. traffic block of 120 minutes shall be demanded for repair of fractures involving 2 cuts and 2 welds. a block of 30 minutes followed by another bock of 90 minutes duration. In case it is essential to resort to gas cutting due to emergency.(Rakesh Saksena) Sd/. traffic block of 100 minutes shall be demanded for repair of fractures involving 2 cuts and 2 welds. about 20 minutes for rail cutting by hacksaw blade. for works involving rail cutting. 4.e. No. A close coordination between the officials of Engineering and Operating Departments should be ensured in case of split block situation. Sd/.W.8. 1. Copy of SC Rly Headquarters lr. etc. dated 20. In case of rail cutting by Hacksaw Blades.in/doku/doku. so that the gaps available at the time of welding during the second block are close to 25 mm. 2. Block requirement for works involving one cut and one weld shall be suitably http://wiki.gov. 2009. CTE vide Para-7 of the above referred Inspection Notes has observed that the Register do not have columns for noting down the name of agency.509/P/AT Welders & Welding. Simultaneously. Divisions are advised to furnish the desired revised format and the number of copies required for each division.C. with the details asked above..(S.11 (type of welder) and Column No.DEN/Co-ordinations of S.20.Way of open line) containing 15 columns for recording various details was issued to Division earlier. On examination of the broken pieces.08 Copy of Headquarters lr.10.DEN/DEN of the section should be advised to take this matter seriously and take necessary remedial action.III.gov.(S.W.35/2008 vide letter No.2008 at km. dated 29. name of welder etc.SAHU) Chief Track Engineer Copy of Headquarters letter No.Alumino Thermic welding [�ENCYCLOPEDIA HOME] reduced.SAHU) Chief Track Engineer South Central Railway Forwarded vide lr.10.12 (date of welding) along with the details for the printed item in the next line. line between BTTRSVPM and GDR-BZA section on 8. Recently one Rail fracture had taken place at km.P. Such Dent/cuts are caused due to mishandling of rails during unloading or laying. A standard printed register for recording rail / weld fractures (for use of SSE/SE/P.C.251/5-3 up line between MCI-MMZ of KZJ-BPQ section for which the cause of failure was also due to dent / cut mark at rail foot. it is advised to carryout thorough inspection of rails in the section and take action to identify and attend such locations.2009 addressed to Sr.12. This issues with the approval of PCE.08.DEN/Co-ordinations of S. 2.iricen.246/CTE/04/Vol.211/30-32 Dn.VIII Dt.2008 addressed to All Sr. 3. dt. Ref: CTE’s Inspection Notes No. Sr. staff at all levels need to be counseling regarding proper handling of rails. Sd/. dated15.Railway Sub: Rail / Weld failures – Dent / Notch marks. http://wiki.Railway. Sd/.6. It was advised to redesign the proforma of the register incorporating these details. Please acknowledge the receipt of this letter. In order to avoid such unsafe situations.1.in/doku/doku.413/GENL/RWF/XXIV. to arrange from Hqrs. No. No. Action taken in this regard may be advised to undersigned.P.php?id=at_welding[24-12-2013 12:20:25] .02.501/I/7/Vol.6. Such type of Dent/Notch marks on UTS rails are serious cause of concerned resulting into Rail fracture. Sub: Standard Register for recording rail / weld fractures – reg. On earlier occasion also one more Rail breakage had taken place on 5. This was reported as Weld failure. In the meanwhile.W. which are required to monitor performance of the same. a deep Dent Mark was noticed on the rail foot close to the SKV weld which was the origin for causing the Rail fracture. the details of welding agency and the name of welder may please be recorded in the Column No. Office by 26.7 2) This office letters of even No.500/. 10. dated 8.iricen. 1) All AT welds in locations where the track has carried more than 50% of the stipulated GMT. A penalty of Rs.11.in/doku/doku.1000/. explanation should be called from the PWI/USFD for the discrepancy and suitable action be taken if the motive behind detecting the higher http://wiki. 3) All AT welds on the outer rails of curves with curvature ½° and above. dated 14.413/Joggling.N. 4) All AT welds on major and important bridges and their approaches on either side upto 100 Mtrs.Alumino Thermic welding [�ENCYCLOPEDIA HOME] Sd/.B/W.07.GUPTA) Dy. if the defective weld is less than 50% of what has been detected earlier by PWI/USFD.CE/Tr.II Copy of lr.11.php?id=at_welding[24-12-2013 12:20:25] .(J. 5) All AT welds on Track where the height of the bank is 4 M and above.07 and20. Board have decided that the following course of action be adopted in future welding contract. 2.gov. dt.8. In case of the defective weld exceeds 4% the certificate issued by RDSO should be cancelled and welder will have to go through with the process of re-certification.07.11. 3. 2) All AT welds in well fracture prone locations.9.11. Till fresh certification is issued Welder should not be allowed to do any work on the track. Ref: 1) CTE/SCs letter Nos.8.of the defective weld is found more than 4%. Please refer to the letters cited under reference wherein it was advised that joggling of AT welds has to be done at the following locations as per the extent instructions and the same should be completed before 31. W.2007 without fail.10. Sub: Precautions to be taken on Passenger intensive routes – Joggling of AT Welds – Reg. 1.. Please ensure Joggled fish plating of all the AT welds in the above locations of your section is completed before 24. Initial USFD testing should be conducted within a month’s time from the date of welding so that the welder with a bad workmanship can be identified and removed from the site.Way-II. There should be a provision of joint checking with firm’s representative.21.6.Track/21/2002/0110/A T Policy.Way on BZA Division.07 addressed to All ADENs & SSEs/SEs/P.DEN/Co-ord/BZA Copy of Railway Boards Lr. Sub: Quality control for welding of rails by SKV process. During the course of joint checking.413/GL/Joggled Fish Plates/P. Sd/For Sr. 4.DEN/Co-ord/BZA.may be imposed for defective welds ranging from 2 to 4% and a penalty of Rs.07. dt.No. This has the approval of Sr.07 without fail and the compliance report should be submitted to this office to advise Hqrs.2005 addressed to PCEs of All Indian Railways. No.9.7.07 and 13. Railways are advised to take necessary action in this regard and compliance report be sent to Board.iricen. Joggle fish plating of the thermit weld on the bridges along with its approaches upto http://wiki... 6. The fist plating should be done using clamps without drilling of holes. This will reduce the wastage of rail and population of additional SKV weld at site.php?id=at_welding[24-12-2013 12:20:25] . Railway to maintain batch wise and welder wise data of each weld at site so that any deficiency in a particular batch or portion or welder can be identified and suitable action can be taken in consultation with RDSO.07 addressed to PCEs of All Indian Railways.AGRAWAL) Executive Director Track (P) Railway Board Copy of Railway Board’s letter No. A firm may be allowed to do the welding of defective weld by wider gap technology.K. Ahemdabad and M/s.2003 stands withdrawn. Therefore. Ltd.5. Joggle fish plating of the thermit welds (irrespective of age) on the outer rail of the curves should be done on priority. Moreover. Sub: USFD testing of AT welds using digital AT weld testers.gov.02. Railway Board has now decided that al ultrasonic testing of AT welds henceforth would be carried out using RDSO approved digital ultrasonic equipment. there are two RDSO approved vendors for the equipment. namely M/s.(S. As on date. dated 30. Sd/. The instructions conveyed to the Railways vide this office letter of even number dated 17.08 addressed to PCEs of All Indian Railways.1 of Manual for Fusion Welding of Rails By Alumino – Thermic Process ) shall be strictly followed by Zonal Railways. Digital Ultrasonic equipment for Aluminothermic Weld was developed by RDSO in association with trade for quite some time.Alumino Thermic welding [�ENCYCLOPEDIA HOME] number of defective welds is suspected.Modsonics Instrument Manufacturing Company Pvt. Six months' time period has been fixed for the procurement of equipment / development of requisite infrastructure. Numbering of SKV weld at site should be done to co-relate a particular weld with a particular batch of portion and welder.(S. dated 08. Mumbai. 5.2. Copy of Railway Board’s letter No.Track/21/99/0910/7. PWI/USFD can himself do the probing operation and view the signals on the monitor simultaneously. 2.in/doku/doku. These Ultrasonic Weld Testers are not only handy but also can record data being a digital equipment. 1% sample joint testing as envisaged in the manual (Para 7. the quality of testing improves drastically with its use. Sd/. Parikh Industries. Board (ME) desired that following precautions should be taken on the passenger intensive routes (Prority-1) and on CC+8+2T routes (Priority-2): 1. Sub: Precautions to be taken on Passenger intensive routes. Therefore.Track/21/2004/0902/7. 7.K.AGRAWAL) Executive Director Track (P) Railway Board. K. The welders whose grade is ‘A & B’ only should be utilize in the field as welders.506.Alumino Thermic welding [�ENCYCLOPEDIA HOME] 100 m should be done. Sd/.iricen. the following amendments are made to the para mentioned below:Existing para No.2.Tra ck/Grade/Genl. CTE has given instructions to assess the performance of the welders an grading should be given to each welder working in your section. . it should be done under line block of adequate http://wiki. Their performance results in terms of defective joints / failed joints shall b shown and considered for awarding gradations. In partial modification to the above Standing order.1.3 of 01. Office of the DRM/Works/SC No. Marks to be awarded: • For Technical knowledge .30 Marks (Based on defective/failed joints) ——Total 100 Marks —– Grading A > or= 90 Marks B < 90 and > or = 75 Marks C < 75 Marks ——CORRECTION SLIP NO. When the welding work is done on the cess full rail length should be leveled by supporting on at least ten wooden blocks on either side. remedial action due to be identified and taken promptly. shall be read as under:= Thermit welding should preferably be done on cess.2.gov. improper fusion or blow holes or presence of fin etc. A database has been developed at the Divisional office and Headquarters. due to some impact or it is due to an inherent defect leading to fatigue like.’B’ or ‘C’.CW. The other welders who are graded as ‘C’ should be utilized for supporting the welder and after they gain confidence. However. It should be ascertained whether weld failure is sudden.1 ENGINEERING STANDING ORDER NO. 3. Each and every weld fracture is to be analyzed by sectional Sr.DEN/DEN. they are supposed to be upgraded. Date 25.php?id=at_welding[24-12-2013 12:20:25] .2007 All ADENs / SC Division Sub: Performance of SKV Welders and Grading.35 Marks • For quality welding . Sample proforma is enclosed to fallow and the details available are to be update and submitted to the undersigned along with the number of weldings done by the individual during the year 2006 till date.in/doku/doku. The guidelines given may be follows.AGRAWAL) Executive Director Track (P) Railway Board. if done in site.5.35 Marks • For Skill in execution..1999 Sub:-Guidelines for containing rail fractures/weld failures.(S. no welding should be done in the field who are not having valid compe6tency certificate and graded as ‘B’ or ‘C’. As ` ‘A’. 4 (b) Periodic testing of complete weld by hand probing of weld head/web and bottom flange using Oº 2MHz. 45º 2 MHz probe ( AT weld foot scanning for half moon shaped defect) and 70º 2 MHz ( 8 x 8 mm) probes. Sd/.No Process involved Welding Time 52 Kg Section 1.1 of USFD Manual. Pre-heating 10 minutes 12 minutes 3 minutes 3 minutes 4. Reaction time. First train passing time 5 minutes 3 minutes 6 minutes 3 minutes 30 minutes 30 minutes 76-81 MINUTES 79-84 MNUTES 8. The rail fastenings for at least five sleepers on either side of the proposed weld shall be loosened to avoid internal contraction stress at the joint during cooling. The frequency of testing in this case is as per 6. it should be done under line block of minimum 75 minutes for SKV welding process.8.P. These are: (a) Testing of weld head/web. removal of burner.2. setting .in/doku/doku. As per this testing defects detected in welds are classified as “ DFW “.|15-20 minutes |15-20 minutes| 2. As per this testing defects detected in weld heads are classified as IMRW and OBSW aide Annexure II. Mould waiting time 6. The approximate time required for various operation for execution of SKV welding in situ under traffic block are indicated below:Sl. The action to be taken for such defective welds is as http://wiki.iricen. Trimming of weld 7. 60 Kg Section cleaning.gov.mould fixing & luting|10 minutes| 10 minutes| 3. tapping and removal of crucible stand 5.Alumino Thermic welding [�ENCYCLOPEDIA HOME] duration. TOTAL Hence. if welding is done in situ.8.1 of USFD Manual. The frequency of testing in this case is as per para 6. SCOPE: Following types of testing for Alumino Thermic welds have been prescribed.php?id=at_welding[24-12-2013 12:20:25] . The action to be taken for such defective welds is as per para 6. Mallikharjun) Principal Chief Engineer USFD Testing of AT Welds ULTRASONIC TESTING OF ALUMINO-THERMIC WELDED RAIL JOINTS 1.1.(G. 70º 2 MHz. which gets covered during through periodic rail testing by SRT/DRT. php?id=at_welding[24-12-2013 12:20:25] . He should communicate to Sec Se about the flaw location who shall ensure the following: ( i ) protection of DFW weld by jog. 6. M&C/NDT/129/2005 or its latest version along with rig for tandem testing. Or 20mmx 20 mm square crystal size. marking and action taken: Classification Marking on both sides of web Action to be taken DFW + + With red paint For NEW Welds: These DFW welds shall be cropped. 70º 2 MHZ. 3. 2 MHz. SE/USFD/shall impose SR 30kmph or stricter immediately.Alumino Thermic welding [�ENCYCLOPEDIA HOME] per Para 6. No. Crack in Head of AT weld Head 3 70º S/C 2MHZ 300 mm 60% FSH on 3 mm Ø hole in the middle of the Flange of AT weld 40% or more ht To detect lack of fusion. Head. Slag inclusion in Flange of AT weld Foot 4 45º S/C 2 MHZ 500 mm 60% FSH on Simulated notch at Bottom of AT weld 20% or more ht To detect Halfmoon shaped defect ay bottom of weld Foot 5 70º S/C 2 MHZ ( 8×8 300m m 60% FSH on Simulated 20% or more ht To detect Halfmoon shaped defect ay bottom Foot mm) notch at Bottom of AT weld of weld 6 45º/45º S/C 2 MHZ (Tande m Techni que) 500 mm 100% of FSH and increase the Gain by 10db 40% or more To detect vertical oriented defects such as lack of fusion in rail head. Slag inclusion in Head&upto mid web of weld Head & Web 2 70º S/C 2MHZ 300 mm 60% FSH on 3 mm Ø hole in head From head 40% or more ht To detect lack of Fusion. Single crystal .gov. Blow holes. 20 mm Dia. defects detected in welds are classified as “ DFW “. the DFW weld shall be replaced with in 15 days. Testing procedure and Classification: Sl. web and foot region below web. 20 mm Dia. Slag inclusion. Fps using min. 8. Couplant : Soft grease shall be used as couplant. © Besides this. after which SR can be relaxed upto 100/75 Kmph for Goods/Pass trains. 5. The action to be taken for such defective welds is as per Para 8. Cable : Co-axial cable for each probe shall be used. 2 MHz.1 no. Equipment : Any RDSO approved model of ultrasonic equipment for Aluminothermic welded rail joints as per RDSO specification No.FPs with clamps. 8 mm x 8 mm crystal size.From web or foot >20% ht To detect Porosity.1 no 4.6 of USFD manual. Defect Classification. This test is termed as Initial Acceptance Test. 45º 2 MHz probe( AT weld foot scanning for clustered defect/ micro porosities in web foot region) and 45º 2MHz ( Tandem probe scanning for lack of fusion). Single crystal . Or 20mmx 20 mm square crystal size.in/doku/doku. However. The DFW weld with SR may be continued in track if the track is to be renewed with in 12 months. For Service welds: These DEW welds on detection.2 tight clamps/2 far end tight bolts one on each side. protection of DFW weld has a been done using jog. The length shall not be more than 2 mtrs. Blow holes. 2 MHz. Porosity.iricen. Blow holes. Double crystal .1 no. 18 mm Dia. welds are also tested after their execution using Oº 2 MHz. As per this testing. Single crystal . ( ii ) In case protection of DFW weld has been done using jog.No Type of Weld Type of testing Testing Schedule Acceptance Test Immediately after welding First Periodic Test One year Routes Having GMT Frequency 45 2 years 30 < 45 3 years 15 < 30 4 years http://wiki. ( ii ) 45º.FPs with 2 far end tight bolts SR shall continue till weld is replaced which should not be later than 3 months. re-welded and tested again. Porosity. 2 MHz.10 of USFD manual. ( iv) 70º. Probes : ( i) Normal/Oº . Web & foot below web 7. 2.3 nos ( iii ) 70º. Weld Testing Frequency ( SKV ) S. Probe Calibr ation Sensitivity Defect Classification( DFW) Type of defect Detected Locatio n 1 Oº 2 MHz 300 mm 60% FSH on 3 mm Ø hole in head From head 40% or more ht. 15 5 years 9. as per need.9 Show pagesource | Old revisions | Backlinks http://wiki.txt · Last modified: 2011/02/14 08:48 by 10.Alumino Thermic welding [�ENCYCLOPEDIA HOME] 1 SKV Further Tests based on route GMT 0 .152.iricen.php?id=at_welding[24-12-2013 12:20:25] . Note: ( i ) Due to unusual high weld failure or abnormal development in some sections. ( iii ) TWR should be planned after the welds have carried 50% of the stipulated GMT of Rails.gov. C:/wamp/www/doku/data/pages/at_welding. Chief Engineer may order testing of welds early. ( ii )The USFD testing can be dispensed with in case of those welds which are more than 15 years old and protected by joggled fish plates with far end tight bolts.in/doku/doku.5. 1. as the scope of such welding is very limited for which the provisions laid down in "Manual for welding of Rail joints by the Alumino-Thermic Process.achieving. (b) & (c). during and after welding by short pre-heating process for . IRS T-19-1994. Alumino.-Omm in vertical and �0.5 Conventional AT welding process which utilised green sand mould has been banned on Indian Railways.MANUAL FOR FUSION WELDING OF RAILS XHE ALUMINO MANUAL FOR FUSION WELDING OF RAILS BY THE ALUMINO-THERMIC PROCESS 1. welding is required to be done to convert flash butt welded panels into long panels and for repair of fracture.T.1 below: http://www. when checked with 1 metre straight edge as shown in Fig. 3.5mm in lateral direction. SCOPE 2. before welding.Rails to be welded shall conform to the tolerances stipulated in the relevant specification as stated in Table . Short preheating is mostly being done by Air-petrol fuel mixture. 1. SELECTION OF RAILS TO BE WELDED 3.1 This manual supercedes "Manual for welding of rail joints by the alumino-thermic process.process of Alumino-Thermic welding which have necessitated revision of Manual issued in April. April. it should be ensured that the end bends of the rails are within + 0. Oxy-LPG & Compressed Air petrol fuel mixture are being developed as these techniques take less time for pre-heating the rail ends to desired temperature resulting in saving of block time with improved quality of joint. 90R and higher rail sections and not standardised for 60R rails. 2.1987. INTRODUCTION 1.3 On Indian Railways Alumino-Thermic welding with short pre-heating process by using high Silica sand mould (C0 2 dried) is being followed at present for welding rails of different chemistry and sections.htm[24-12-2013 12:25:49] . 3. Normally new single 'rails shall not be welded by A.2 There have been many technological improvements in the . The welding of 60R rails will be done by .4   A. 1.1 This manual outlines the method of welding and the precaution and steps to be taken before. Same considerations also led to revision of Indian Railway Standared Specification for fusion welding of rails by alumino-thermic process which has now been revised and issued under the serial No.Thermic welding techniques with short pre-heat process have been standardised for 75R.2 New rails .5mm.conventional AT welding process using green sand mould. 3. satisfactory weld. T.gov.1(a). April 1987' will continue to be applicable. 1987" 1.1 For both new as well as second hand rails.indianrailways. welding.in/railwayboard/uploads/codesmanual/FWRATP/Thermic%20Process_Data. old serviceable rails may be welded subject to the following conditions: i) Obsolete rail sections and rails.gov. however.indianrailways.htm[24-12-2013 12:25:49] .MANUAL FOR FUSION WELDING OF RAILS XHE ALUMINO 3. be obtained in special cases. be welded. older than 50 years shall not. The height of rail and width of rail head shall not be less than the values as indicated in Table-2 : http://www. ii) The Chief Track Engineer shall satisfy himself that second hand rails have a substantial rail life to make it a safe and economical proposal. iii) Rails shall be free from corrosion or excessive wear. normally.3  Second hand rails . Specific approval of the Railway Board may.For conversion of existing single rails/ Short welded panels into SWP/LWR/CWR or during secondary  rail renewal.in/railwayboard/uploads/codesmanual/FWRATP/Thermic%20Process_Data. in the rails shall be removed before welding. End cropping may be suitably' increased so as to ensure that rail ends are within the tolerances as specified in para 3. welds with portion and technique developed by Thermit portion plant'/N.MANUAL FOR FUSION WELDING OF RAILS XHE ALUMINO The limit of lateral wear in the rail head as laid down in Table-2.1 Technique for welding Welding techniques approved provisionally or for regular adoption by Railway Board/RDSO should only be adopted for welding of rails. (As on 31-12-97) : 4. The rail flange bottom shall be visually inspected to ensure freedom from defects like dent.1. vii) Second hand rails shall be match .in/railwayboard/uploads/codesmanual/FWRATP/Thermic%20Process_Data. the ends should be cropped to eliminate fish bolt holes. Following course of action may be adopted for welding of rails through approved portions manufacturers. so that rails having cracks and internal flaws are excluded from welding. 6mm may be followed subject to uniform gauge without any abrupt change. wheel burns. However in unavoidable circumstances. approved/ provisionally approved for extended field trials. with ultrasonic flaw detector apart from visual inspection. iv) Rails shall be tested before welding. consumables. 12 firms are approved only for executing A. In order to achieve satisfactory running on welded rail panels. Further. Apart from this departmental welders are also trained and certified by TPP for AT welding of rails with the technique developed by them. where rails of Grade 710 (72UTS) rail chemistry and that of Grade 880 (90 UTS) chemistry are to be welded.1. T. vi) The rail ends shall be cut by sawing or using abrasive disc cutter and not by flame cutting. Present status of welding techniques. only Four firms are approved for manufacturing of portion and execution of welding. v) Even where cracks/flaws have not been detected during visual/ USFD examination before welding. Rly. corrugations and wear of rail seats shall not be used for welding. notch. viz. rails with excessive scabbing.1 . of various A. the ends of second hand rails should be suitably cropped so as to eliminate fish bolt holes. portion manufacturing firms is given at Annexure. equipments and RDSO certified http://www.indianrailways. 4.gov. xi) While using second hand rail panels for secondary renewal. viii) The rolling marks on the web of rails shall be checked before welding to ensure that generally rails of different qualities are not welded together. the portion of Grade 880 (90 UTS) chemistry shall be utilised for welding. Kinks.T.marked before releasing from track to enable matching of the rail ends at the time of welding. if any. labour contracting firms  and by departmental welders: i) Large scale welding a) Approved portions manufacturing firms with their portions./Lucknow (TPP). released from LWR/CWR sections. EXECUTION OF JOINTS AT SITE 4.htm[24-12-2013 12:25:49] . If rail ends do not have bolt holes.1 Presently. corrosion etc. the ends may be cropped to a distance of minimum 150mm for AT welds and 85mm for Flash Butt welds from the centre of welded joint to eliminate heat affected zone of welds. gov. the portion can be used even after a long time. AT portion is sensitive to moisture. 4. consumables of TPP and welders/welding supervisors certified by RDSO. open line works. doubling. the same cannot be removed even by drying as the ingredients react chemically. welding also forms a small portion of work. web and head upto 50mm shall be thoroughly cleaned using kerosene oil and brushing with wire brush to remove all dirt. 4.1 The "portion"  used for welding shall conform to the technical requirements as mentioned in IRST-19 1994. 4.2 Portion for welding: 4.1. grease and rust before welding.3 and 4. All such portion should not be used for welding.MANUAL FOR FUSION WELDING OF RAILS XHE ALUMINO welders/welding supervisors. ii) Casual welding (a) Agencies as mentioned in para 4.indianrailways. The rail end face and adjacent sides at foot (top & bottom) . If packing is intact and there is no entry of moisture .2 Shelf life of portion: No specific shelf life has been indicated for AT welding portions. The composition of thermit welding team is given in Annexure-3. (1) (a). Once the portion absorbs moisture. However. consumables and preferably equipment also of approved portions manufacturers as per the approved welding parameters as given in Annexure . welding in case of Turn -key contracts: in case of turn-key contracts for gauge conversion. following procedure may be adopted for permitting use of portions beyond two years after the date of manufacturing: (a) One random sample per batch of 300 or part there-of may be drawn from the portions available in stores.2. Only RDSO certified/passed portions should be used for welding. If the values obtained in above tests are within the specified values as given in para 4. These tests should. http://www. 4.htm[24-12-2013 12:25:49] . (d) The rejected portions are to be disposed-off by igniting five portions at a time in a pit away from the store. (b) TPP certified departmental welders for welds of 25mm gap using portion.3 Equipment and staff for welding The list for one set of A.1 of IRS T19-94.1. iii) AT.1 (i) (a) & (b) above. in which A.4 Preparation of rail ends to be welded. Following tests should be conducted on the test joints.1.3. c) Departmental welders certified by TPP with portions and consumables manufactured by TPP only.2. welding equipment by short preheating process is given in Annexure-2 .1. the batch represented by the sample can be used otherwise batch should be rejected. suitable provisions may be kept in the contract conditions for executing welding by the agencies as mentioned in para 4. (b) The sample shall be tested for reaction test. new lines.in/railwayboard/uploads/codesmanual/FWRATP/Thermic%20Process_Data.T. the batch represented by the sample can be used without further tests. Any burrs at the rail ends shall be removed by chiselling or grinding. T. c) In case the reaction is found to be quiet or boiling a  test joint should be made from one more sampleselected from the batch. etc.2.1. be conducted at Zonal CMTs organisation and/or the Flash Butt Welding Plant. (i) Aluminium content test (from riser of the joint) (ii) Load deflection test. Life of portions would depend on the quality of packing and storage condition. If the reaction is normal . b) Labour contracting firms with portions. The suitability of the "portion'' for the welding process in respect of the type and section of rails to be welded shall be ensured before commencing welding. etc.2 Vertical alignment: The joint shall be kept higher by 3 to. both horizontally and vertically. The uniformity and verticality of the gap shall be measured by a gauge prior to welding.1 Lateral alignment: The two rail ends. 4mm for 72 UTS rails and 2 to 2. both sides 0f the joint. 4. followed by passage of CO 2 gas. 4.2 When the welding work is carried out on cess.7. it shall be ensured that the centre. 4. hydraulic/mechanical rail tensor of suitable & approved design should be used for maintaining correct rail gap during welding. no alumino-thermic welded joint shall be located closer than 4 metre from any other welded or fish plated joint. The moulds should touch the bottom of rail foot to ensure proper size of collar at the bottom. 4. each pair of moulds shall be examined for defects.6. 4. To protect the rail top table from metal splashes during reaction. for repairing fractured/ defective welds.4.1. This shall be achieved by wedges applied on the rail supporting. 4. correctly aligning the rail ends on the gauge face.4 mm for higher UTS rails when measured at the end of 1m straight edge (as a compensation against sagging caused by differential shrinkage on cooling) (Fig. clamps.1 In case of in-situ welding the rail' fastenings for at least five sleepers on either side of the proposed weld shall be loosened.2) .5 mm when checked with a 1.5 Gap between rail ends The two rail ends to be welded shall be held in position with a uniform and vertical gap as per gap specified in Annexure-l . dampness. the welding of joint shall be temporarily abandoned and joint allowed to cool. Excessive pressure may cause breakage of mould and dropping of sand inside the mould cavity.htm[24-12-2013 12:25:49] . The prefabricated moulds shall be handled withy care as  they are fragile and liable to breakage. In case of wide gap 50�l/ 75�1 mm welding.1 Only prefabricated moulds supplied by the portion manufacturer shall be used for welding.6 Preliminary work prior to welding 4.MANUAL FOR FUSION WELDING OF RAILS XHE ALUMINO 4. 4.2 Gap between rail ends may be rechecked after completion of alignment. cracks.4.1 Normally. Datum marks shall be made on foot of both rails as well as on joint sleepers in order to observe any longitudinal movement of rails.1(a) & (b)). The rails shall be properly aligned in horizontal and vertical direction and held in position.8.1.8. blocks on.8. blocked vents etc. These are to be made by mixing high silica sand to IS:1987 with sodium silicate to the required consistency. and defective moulds discarded.1. line of the rail gap coincides with the centre line of the mould to avoid cross joint. The sleepers adjacent to the joint to be welded shall be shifted to obtain a clear working space of 250 mm on either side to accommodate the moulds.1 The rail ends to be welded shall be aligned in horizontal and vertical planes to the dimensional limits indicated below:4. shall be tightened by the application of adequate pressure.0m straight edge at rail ends (Fig.6.indianrailways. Care shall be taken during application of adequate pressure.gov. 4.1.8.2  Before mounting on the rail ends to be welded. Any difference in the widths of rail heads shall always be fully kept on the non-gauge side. after fixing. The rails shall then be properly aligned. The mould jackets/shoes holding the pre-fabricated mould in a snug fit condition.4 After fixing the moulds. preheating equipment.7.7. of liquid weld metal. after alignment shall be within �0. It is essential for the moulds to fit flush to each other across ' the bottom of the rail flange which can be checked by feeling with fingers across the junction of the two halves of the moulds and by looking down the riser aperture.7 Alignment of rail ends before welding 4. If excessive longitudinal movement occurs during pre-heating and produces a welding gap outside the prescribed limits.8 Fixing of mould 4. the adjacent rail surface on either side of the moulds shall be covered with metal cover or smeared with luting http://www.7. full rail" length shall be levelled by supporting on at least ten wooden blocks on either side.7.in/railwayboard/uploads/codesmanual/FWRATP/Thermic%20Process_Data. 4. In LWR/CWR territory. it shall be ensured that the end faces are vertical. These prefabricated moulds shall have adequate permeability for escape of mould gases and adequate reinforcement. 4. 4. to avoid mould crushing during transportation and welding. During fixing the moulds.3.7. the gap between mould and the rail shall be packed firmly with luting sand to prevent leakage. shall be thoroughly hand mixed and poured into the crucible striking the crucible wall so that the bottom plugging remains undisturbed. the molten steel shall be tapped into the mould by striking the closing pin with a tapping rod. The crucible shall then be brought to the proper position over the mould in line with the pouring gate of the mould with a vertical distance of about 50mm between the tap hole and sand. the joint should be cooled to ambient temperature and . or relining as necessary shall be carried out. The reaction shall not be vigorous or boiling.3 Preheating time . the rail end may be heated to an extent so as to achieve temperature of about 600�20�C and welding of joint may be completed. asbestos powder and slag powder. By the time the reaction is complete.9. 4. In case of alloy steel http://www.2   In welding process using air petrol burner. the metal shall be out tapped. about 3 seconds shall be allowed for the separation of slag from the metal.4 After preheating the rail joint . In case of pre-heating by Oxy-LPG process.70 Kg/cm 2(100�10 lbs per sq. In cases of out tapping. 4.  the burner shall be removed quickly and the gap closed with a dried sand core in case of central pouring to prevent loss of heat and turbulence during flow of metal.10. care shall be taken not to damage the refractory crucible lining. 4.0 Kg/cm 2 and 2. core /top of the pouring gate. inch). The pre-heating shall be done from the top of the mould box for stipulated period for welding technique adopted. During cleaning.1   The crucible lined with refractory material (magnesite/crushed alumina slag) and fitted with bottom stone and thimble shall be preheated before making the first weld of the day to ensure freedom from moisture. 4. self tapped metal enters the mould.5  After pouring. It shall be ensured that since the commencement of the reaction. However if temperature can be-measured. so as to achieve a temperature of around 600�20�C. 4.2 Slag shall be cleaned from the crucible after each reaction. web and foot of both the rail ends are heated uniformly.9. From time to time or in case of any doubt with a view to maintain proper quality control.3 The crucible shall be positioned relative to the pouring gate with respect to its height from the mould after it has been placed on the stand mounted on the rail head.in/railwayboard/uploads/codesmanual/FWRATP/Thermic%20Process_Data.e.Preheating time would be about 10 to 12 minutes and 2 to 2. If.10. 4.5 minutes for Air-petrol and Oxy-LPG preheating techniques respectively.0-8. thermit steel is tapped within the time limit as specified in Annexure-1 . temperature measuring devices like 'Optical pyrometer. the rail ends shall be uniformly pre-heated throughout the rail section with specially designed air petrol/ compressed air petrol/ oxygen -LPG burner as the case may be. cut and rewelded. The lining shall be examined regularly and patch repairing. the crucible and swivel stand shall be removed and kept aside without disturbing the joint. The tap hole in the crucible shall be sealed with closing pin. The time period between removal of burner and tapping of metal should be as minimum as possible. After the reaction subsides.gov. If the reaction is found to be boiling.MANUAL FOR FUSION WELDING OF RAILS XHE ALUMINO sand upto 15cm on either side.1 After fixing and luting of the moulds.0-2. 4. While closing. The burner shall be properly adjusted during preheating to ensure that the head. The portion  for the required technique. thereafter Oxygen supply should be opened.10 Welding 4. the sparkler shall be ignited & inserted in the portion at the centre top to start the reaction. In this case also. Thereafter. Contact type pyrometer' or temperature indicating crayons may be used for measuring rail end temperature just after completion of preheating i. Care shall be taken to ensure that the crucible does not move from its position during tapping.9 Preheating 4.10.. Oxygen supply should be stopped first followed by LPG supply. Vigorous reaction and loose closing of crucible may cause self tapping. The flame shall be properly adjusted to achieve the desired rail temperature . after removal of burner. The portion shall be coned to the centre of the crucible and a sparkler be placed at the top. in any case. if necessary.5 Kg/cm 2 respectively.4 Special emphasis shall be given to the tank pressure efficiency of burner & flame condition for achieving required rail temperature within the stipulated time.10.indianrailways.10. While preheating with OXY-LPG burner LPG supply should be opened first and the gas ingited. pressure for Oxygen and LPG cylinders shall be adjusted in the range of 7.9. The actual preheating time would depend upon the rail section and welding technique adopted as given in Annexure-I. the metal shall be outtapped.htm[24-12-2013 12:25:49] .the process of welding restarted a fresh. the joint shall be rejected. the compressor tank pressure during operation of the burner shall be maintained at 7 �0. When pouring is over. 4. 4.9. which may be judged by looking into the crucible through colored glass to IS:5983. molten metal shall be allowed to cool and solidify with mould intact for the stipulated time (mould waiting time) depending upon the rail section and ambient temperature. 5.4 mm.in/railwayboard/uploads/codesmanual/FWRATP/Thermic%20Process_Data.1. List of approved manufacturers of Rail profile weld grinder and Weld trimmer  is  given at Annexure-4. This lower hardness is due to transformation of rail steel occurring at cooling rate much lower than that achieved during the original head hardening operation. in) Finishing of top surface: + 0. Such a hardness difference can lead to differential plastic deformation during wheel rail contact which may cause localised cupping.2 Post weld packing pf sleeper Before the passage of traffic. The rail table shall first be ground down to original profile and checked by a 1 m straight edge. manual chipping may be resorted to.6 During the trimming operation. In the case of in-situ joints. Head Hardend rails. In I case. the wedges used for aligning should be removed and joint sleepers which were shifted to obtain the clear gap of 250mm on either side as per clause 4. OPERATIONS SUBSEQUENT TJ2 WELDING 5.1 shall be re-shifted to the original location and repacked.end of one metre straight ii) Lateral alignment: Variation^ not: more than �0. 10 cm straight edge. must be subjected to controlled quenching for a specific time by the arrangement approved for the technique.10. immediate arrangement to adequately cover the site shall be made.6. the rains start while the joint is under execution.-0 mm measured at the end of. 4. of suitable & approved design without knocking out the mould.2  Tolerances on finished welds. after the removal of wedges. it shall be ensured that the wedges used in aligning are in their proper places without loosening.gov.MANUAL FOR FUSION WELDING OF RAILS XHE ALUMINO rails.1 Post.2 In case of welding of Head Hardend rails.1 After the excess metal is trimmed off. 5. 5. 5. weld cooling 5. While grinding.4. This should be followed by grinding of the sides of rail head. manual chipping should be done. iv) Head finishing on sides: �0. full rail section upto 300 mm on either side of the joint shall be heated by using burner during this period. and they are not removed for at least 20 minutes after stripping.4 Grinding 5. The mould shoes shall be removed just prior to completion of mould waiting time.4.10. so as to control the cooling rate of the weld zone.3  Passing of traffic The first train should be allowed to pass on the newly welded joint only after 30 minutes have elapsed since pouring of weld metal. In the eventuality of sudden failure of weld trimmer .5mm measured at centre of one metre straight edge.1.1   110 UTS alloy steel rail joints ( Chrome Manganese and Chrome Vanadium type ) are required to be slowly cooled immediately after trimming by fixing an insulation hood (fig. 5. The accuracy of grinding shall be checked by using 10 cm straight edge. the grinding shall commence only after the sleeper fastenings are refixed. In case of welding of old rails . if it is not possible to use weld trimmer due to flow of metal at rail head.indianrailways. After the mould waiting time has elapsed.-0 mm measured at the . http://www. 4. therefore. Packing of these resifted sleepers should be carried out gently and carefully. All the finished joints shall be checked to ensure that the joint geometry is within the following tolerances: i) Vertical alignment: 'Variation not more than +1. Use of hand files should not be resorted to except in unavoidable circumstances. the trimming should be done by using weld trimmer. only light pressure should be applied and grinding wheel should be moved to and fro to avoid local over heating. The mould waiting time is generally 4 to 6 minutes for 25mm gap joints and 12 minutes for 75mm gap joints.htm[24-12-2013 12:25:49] .1) lined with asbestos. and that too only by knocking towards the rail. 5. the grinding of the remaining metal on the rail table and the sides of the rail head shall be carried out only with rail profile guided grinding trolley of approved design. The hood must be kept around the joint for at least 20 minutes.7 No welding shall be carried out if it is raining. Necessary speed restriction shall be observed until the grinding operation is over. the average hardness of the HAZ of the rail becomes considerably less than the parent rail hardness.3mm over gauge side of the rail head measured at the centre of 10 cm straight edge. The runner & riser must not be removed until cold.5.0mm. irrespective of its location in that kilometer.2 5. Any joint.indianrailways.5. 6. year. blow holes etc. The welded joints shall be serially numbered in .4.2 Dimensional Check. 5. by the firm. (ii) Every year at locations prone to corrosion as defined  in para 249 (i) of IRPWM. This should be done by punching on an Aluminum strip of suitable thickness and dimension of 30 mm x 100 mm which should be fixed to the web of the rail with epoxy adhesive at approximately 300 mm from the joint.7. 6.4. The frequency may be increased depending on the site conditions. (iii) On condition basis at locations which are prone to severe corrosion (areas of severe corrosion to be decided by territorial Chief Engineer / CTE). free of dost. 5. it shall be numbered 89.2.1  Visual Inspection .a kilometer. 5. No punch marking should.3 Ultrasonic Flaw Detection Test All the fusion welded joints shall be ultrasonically tested and accepted by the purchaser or his representative as per the "Procedure for ultrasonic testing of thermit welded rail joints given at Annexure-8. which shows any visible defect should be rejected.   *** Agency  *** Specific person number *** Weld No.All finished joints shall be checked for dimensional tolerances which should be within the tolerances as specified in para 5. PWI shall maintain THERMIT WELD REGISTER as per proforma given in Annexure . the last thermit weld number in a particular kilometer was 88 and subsequently a thermit weld has been executed.3 The procedure for painting of weld collar for thermit welded rail joints to protect against normal corrosion and severe corrosion is outlined in Annexure-6 and Annexure-7 respectively. 6. for joint geometry. .7 PAINTING OF THERMIT WELDS 5.gov.in/railwayboard/uploads/codesmanual/FWRATP/Thermic%20Process_Data. ACCEPTANCE TESTS 6. Agency.All the welded joints shall be examined carefully to detect any visible defect like cracks.7. For example.7. Any joint found not conforming to the above stipulations shall be cut and rewelded. welder's code and weld number of the welded joint in the following manner: joint in the following manner:   ** Month  ** Last two digits of year. in case of old rails. 5. This testing shall be completed as early as possible but in any case before the contractor/welding team leaves the welding site. 6.2 In service painting ( maintenance painting) of thermit welds should be carried as per following frequency: (i) Once in four years in areas not prone to corrosion.1 Painting of weld collar should be done on all welds to protect them against corrosion immediately after the welding. Repair welds/additional welds done at a later date may be given continuing weld number in that kilometer.6 MARKING Each joint shall have a distinctive mark indicating: month. dispensations may be permitted by Chief Engineer.MANUAL FOR FUSION WELDING OF RAILS XHE ALUMINO Note:  In specific tales.5 Record of Joint Geometry The details of geometry of each joint shall be jointly signed by the firm's and Railway's representative and kept as record. be done on the rail . The method of checking the geometry of welded joints is illustrated with sketches in Fig. The procedure of painting and specification of paint is outlined in Annexure-6 & Annexure -7. 5.htm[24-12-2013 12:25:49] .4 Rewelding  of Defective Joints http://www. MANUAL FOR FUSION WELDING OF RAILS XHE ALUMINO 6.4.1 All the joints found to be defective as per acceptance tests as given in clause 6.1, 6.2, & 6.3 and/or joints failed in guarantee period as specified in para 7.3 will be cut and rewelded by the firm free of cost using their portions, equipments, labour & consumables. 6.4.2 Where one bad joint, is required to be replaced by two new joints, the entire cost of both the joints shall be borne by the firm. 6.4.3 All the rewelded joints should meet the acceptance tests as indicated in Paras,-6.1 to 6.3 7. Sample Test Joint 7.1.1 One out of every 100 joints welded shall be selected at random by the purchaser or by the; inspecting officer within one month of welding and subjected to Hardness, Transverse load/ deflection tests and Porosity as per clause 4.2 of IRST-19-1994 (reproduced partly as Annexure-9 for ready reference) and the joint shall comply with the provisions laid down therein, 7.2   If the sample test joint fails to satisfy any of the requirements of specification IRST-19-1994, the Railway will be at liberty to suspend further welding. However, two more randomly selected joints from the same lot of 100 joints shall be subjected to retests as per clause 4.2 of IRST-19-1994. Both the joints should clear all the tests. If this report is also not satisfactory  further welding of joints shall be suspended until the firm's welding technique has been examined and the same satisfies the requirements of clause 4 of IRST-19-1994, The clearance for recommencement of welding shall be given by RDSO. 7.3 GUARANTEE 7.3.1 Rail joints welded by a firm shall be guaranteed against failure for a period of two years from the. date of welding the joints in track or from the date such welded joints made in cess are inserted in the track. Any such welded joint which fails within the guarantee period shall be rewelded free of cost by firm as per stipulations of clause 6.4. 7.3.2 In case of failure of sample test joint (refer Clause 7) , the period of guarantee for 100 joints represented by the sample joint shall be extended for a further period of one year. In case of failure of joints or joints exhibiting signs of failure by cracking within extended period of guarantee, the joints shall be rewelded free of cost by the supplier as per stipulations of Clause 6.4. 7.4 The welded joints with the extended period of guarantee shall be marked 'X' with Yellow paint on the outer side of the web of the rail near the joint in addition to the marking prescribed in clause 5.6. Such marked joints shall be kept under careful observation by the purchaser. 8. OTHER REQUIREMENTS 8.1 Welding shall be supervised by trained welding Supervisor and carried out by trained welder having valid competency certificate from RDSO/ TPP, NR, Lucknow in their possession. 8.2 A welding supervisor shall supervise not more than two welding teams deployed within 50m distance at a time. 8.3 A copy of the thermit welding Manual shall be available with each PWI and at each welding site. 9. PRECAUTIONS While carrying out welding at site, the following precautions shall be observed:i) It should be ensured that the portion being used Matches with type and chemistry of rail, ii) Rail ends should be square, iii) Alignment of rail ends should be perfect as checked by straight edge, iv) Rail ends should be properly cleaned with kerosene oil and wire brushes. v) Stop watch should be provided to the welding supervisor at each welding site, vi) Pressure in the tanks/cylinder should be properly maintained during pre-heating. http://www.indianrailways.gov.in/railwayboard/uploads/codesmanual/FWRATP/Thermic%20Process_Data.htm[24-12-2013 12:25:49] MANUAL FOR FUSION WELDING OF RAILS XHE ALUMINO vii) Correct gap between rail ends at head, web and foot shall be ensured. viii) Correct preheating time for rail ends shall be ensured. ix) Tightness of clips fitted with hose connections to compressor tank and burner shall be checked before commencing preheating, x) Nozzles of burners shall be cleaned periodically to avoid back-fire. xi) The compressor tank shall be kept at least 2 to 3 metres away from the burner to prevent fire hazard. xii) The tapping shall be done within the time specified for that particular technique. Welding parameters for techniques presently being used are available at Annexure-1 . For special type of welding i.e. 75mm gap, Combination joint etc. the time of reaction & tapping shall be as stipulated by RDSO for that particular welding technique . xiii) Arrangements for giving first aid shall be available at site. xiv) Welders should be provided with gloves and coloured glasses. xv) Boiling portion shall be out tapped. xvi) No moist portion/torned portion bag shall be used for welding. xvii) Dampness in moulds can lead to porosity and early fatigue failure of welds. xviii) Only those contractual agencies as have clearance from the RDSO/Railway Board can execute welding work. Supply of portions must be from sources approved by RDSO/Railway Board. xiv) Many weld failures show evidence of badly cut rail ends. The evenness and verticallity of a rail cut depends solely upon the skill of the welder. With portable disk cutters, very little skill is required to produce good cut. 10. DEFECTS IN A.T. WELDING The major types of defects which can cause weld failure because of improper weld execution are given at Annexure -10. Annexure - 1 http://www.indianrailways.gov.in/railwayboard/uploads/codesmanual/FWRATP/Thermic%20Process_Data.htm[24-12-2013 12:25:49] MANUAL FOR FUSION WELDING OF RAILS XHE ALUMINO http://www.indianrailways.gov.in/railwayboard/uploads/codesmanual/FWRATP/Thermic%20Process_Data.htm[24-12-2013 12:25:49] gov.indianrailways.MANUAL FOR FUSION WELDING OF RAILS XHE ALUMINO ANNEXURE-2 http://www.htm[24-12-2013 12:25:49] .in/railwayboard/uploads/codesmanual/FWRATP/Thermic%20Process_Data. in/railwayboard/uploads/codesmanual/FWRATP/Thermic%20Process_Data.indianrailways.gov.MANUAL FOR FUSION WELDING OF RAILS XHE ALUMINO http://www.htm[24-12-2013 12:25:49] . htm[24-12-2013 12:25:49] .in/railwayboard/uploads/codesmanual/FWRATP/Thermic%20Process_Data.indianrailways.gov.MANUAL FOR FUSION WELDING OF RAILS XHE ALUMINO ANNEXURE-3 COMPOSITION QE THERMIT WELDING TEAM (COMPRESSOR TANK-WISE)   Designation Welder Grade I/Grade II Welder Grade III/ Skilled Artisan Helper Khalasi/Khalasi Gangman Numbers 1 2 5 As per work load Note: The composition of welding team has been framed taking into account that trimming and grinding operation would be done by Weld trimmer and Rail profile grinder. ANNEXURE-4 http://www. MANUAL FOR FUSION WELDING OF RAILS XHE ALUMINO ANNEXURE-5 http://www.indianrailways.gov.htm[24-12-2013 12:25:49] .in/railwayboard/uploads/codesmanual/FWRATP/Thermic%20Process_Data. indianrailways.in/railwayboard/uploads/codesmanual/FWRATP/Thermic%20Process_Data.gov.htm[24-12-2013 12:25:49] .MANUAL FOR FUSION WELDING OF RAILS XHE ALUMINO http://www. bituminous.2 If required.1 Remove dust.2 Scrub welded area with water to make it free from slag and other water soluble compounds. ANNEXURB-7 PROCEDURE FOR PAINTING OF WELD COLLAR FOR THERMIT WELDED RAIL JOINTS TO PROTECT AGAINST SEVERE CORROSION A. 2.indianrailways. on either side.3 Painting should be carried out by brush. brushing. loose rust and mill scale by wire brushing. acid. a second coat of the same paint may be applied after a minimum of 8 hours drying. apply a second coat of the same paint. 2. NEW WELDED JOINT 1. and flaked paint from the welded joint by wire brushing. Painting procedure.3 Painting should be carried out by brush only.2. NEW WELDED JOINT 1. Surface preparation:1.1 Apply one coat of high build Epoxy paint (Two pack) conforming to RDSO specification No. 1. B Maintenance Painting (For old Painted joints) 1. 3. Painting procedure:2. Make it dry. 2.2 Scrub welded area with water to make it free from slag and other water soluble compounds. loose rust and mill scale by wire brushing.0 Painting procedure2.1 Remove dust.htm[24-12-2013 12:25:49] . Surface Preparation:1. alkali. bituminous. brushing. Petroleum hydrocarbon or any other suitable solvent. alkali & chlorine resistant to IS:9862-81 or bituminous emulsion to IRS P-30-96 on welded area and 10 cms on either side. M&C/PCN111/88 on the welded area up to 10cms. 1. Acid. Surface preparation: 1. 2.2 Degrease the surface by. The list of approved manufacturers for the above quality of paints is issued every year by DG/M&C/RDSO/LKO to Zonal Railways. 2. 1. dirt. water and chlorine resisting.gov. B Maintenance Painting (For old painted joints) 1.in/railwayboard/uploads/codesmanual/FWRATP/Thermic%20Process_Data. 2.1 Remove dust. lead free.1 Apply one coat of ready mixed paint. 2. Allow it to dry.1 Apply one coat of ready mixed paint. Black. if oil or grease is present. drying. Lead free.2 After 8 hrs. conforming to IS:9862-81 on the welded area and 10 cms on either side. Surface Preparation:- http://www. black. Make it dry.MANUAL FOR FUSION WELDING OF RAILS XHE ALUMINO ANNEXURE-6 PROCEDURE FOR PAINTING OF WELD COLLAR FOR THERMIT WELDED RAIL JOINTS TO PROTECT AGAINST NORMAL CORROSION A. RDSO specification No. dirt. The flange and the web. The paint should be procured along with the thinner recommended by the manufacturer of the paint. iii) M/s Goodlass Nerolac Paints (P) Ltd. M&C/PCN111/88 on the welded area up to 10cms.1 Apply one coat of high build Epoxy paint (Two pack) conforming to RDSO specification No. 3.htm[24-12-2013 12:25:49] . 2. Sembium Madras . on either side. Nariman Point. NOTE: 1. "Huzur Gardens'. M&C/PCN/II/TR/3 dt. The sensitivity so adjusted shall be considered as normal gain setting and shall be utilised during ATW testing.. PB No.. ANNRXURE-8 PROCEDURE FOR ULTRASONIC! TESTING OF ALUMINO THERMIC RAIL. 3. 70� and 80� probes in accordance with the procedure laid down in para 4. JOINTS 1. Nerolac House . The rail table shall be dressed to obtain reasonably flat and smooth surface.indianrailways. Bombay .1 Surface preparation After execution of the AT weld.gov. iv) M/s Shalimar Paints Limited.3 Sensitivity The equipment Sensitivity shall be normal.13/14-5-91. 2. Ganpat Rao Kadaw Marg. is present. 1546. The list of probable suppliers is given below as per Letter No. should be used.2 Couplant Water/oil/soft grease shall be used as couplant. by the thinner after use. General conditions of test 2. v) M/s Berger Paints India Ltd. http://www.1 Remove dust. Bombay .400 013. kerosene oil etc..600 011. 13/14-5-91 : i) M/s Asian Paints (India) Ltd.e. M&C/PCN/II/TR/3 dt. "Nirmal' 5th floor. surface unevenness etc. 2. Scope This procedure covers the requirement of ultrasonic testing of alumino thermic (AT) welded rail joints immediately after execution of the weld. dirt. 32. 2.700 071. and flaked paint from the welded joint by wire brushing. The painting shall be carried out by brush only. 13. Brush shall be cleaned. 2.700 071. Chowringee Road.400 421. Calcutta . the welded zone shall be dressed properly to facilitate placement of probes and to avoid incidence of spurious signals on the CRT.MANUAL FOR FUSION WELDING OF RAILS XHE ALUMINO 1. Hence prepare only that much quantity of paint which can be consumed in less than 5 hours.in/railwayboard/uploads/codesmanual/FWRATP/Thermic%20Process_Data. if oil or grease. 1. The sensitivity level shall not be altered during the course of testing. M&C/PCN-111/88 has been circulated vide RDSO's letter No. up to a distance of 200mm on either side of the weld collar shall be thoroughly cleaned with a wire brush to ensure freedom from dust. The Epoxy based paint recommended is a two pack system with a pot life of around 5 hours. Allow it to dry. Camac St. 4. Lower Parel. ii) M/s Addison Paints & Chemicals Ltd.. No other thinnner i.2 Degrease the surface by Petroleum hydrocarbon or any other suitable solvent. Calcutta . Painting procedure:2. 4.0 division horizontal scale.indianrailways. therefore.3 Cable One co-axial cable of suitable length for connecting 80� probe to flaw detector shall be used.25 MHz Single crystal for hand probing 3. The selectors switch may be set to single crystal mode. Switch on only the normal probe and bring it above 3mm dia hole drilled in the head of the test rail. 1. 3. 4. When the probe is just in the reflecting range.gov. Apparatus required 3.           . 4.4.MANUAL FOR FUSION WELDING OF RAILS XHE ALUMINO 3..3 Alignment of probes The alignment of normal and 70� probes fitted with the trolley may be checked by placing the rail tester on the test rail using water/oil as a couplant and ensuring that the probes travel along the vertical axis of the rail.htm[24-12-2013 12:25:49] . 4. http://www. 4. shall correspond to 25mm. Keep the switches of all the probes in Off positions and turn the Potentiometer knobs of all the probes to 50% of their highest working range. the following probes shall be utilised: a) Normal (0 0) . a pulse corresponding to the hole shall appear on the screen which during onward travelling shall show higher amplitude.1 Place the trolley on the test rails shown in Fig.4 Sensitivity setting for 70� probes 4.. The length should not exceed more than 5m.         .1 Equipment Any model of RDSO approved rail tester shall be considered suitable for testing of AT welded rail joints.in/railwayboard/uploads/codesmanual/FWRATP/Thermic%20Process_Data. 1.2 Switch on only 70� forward probe and move the equipment towards the drilled hole of 3mm dia.. In this case a flaw signal shall appear moving from left to right. in rail head.2 Test Rail The sensitivity of the ultrasonic equipment shall be set with the help of a standard AT welded rail piece of 1.. Sensitivity setting procedure 4.3 The forward probe shall be switched off and the 70% backward probe shall now be switched on. 4 MHz Double crystal fitted in trolley b) 70�. Manipulate the potentiometer control knob to obtain echo height of 60% of full screen height at 1. This can be accomplished through suitable manipulation of relevant potentiometer.1 Calibration The equipment shall be set for a depth range of 250mm by manipulating the depth control knob suitably. c) 80�. At this location the height of the pulse shall be adjusted to 60% of full screen height by suitably manipulation of the gain knob. The signal height in this position shall also be adjusted to 60% of full screen height. The equipment should be progressively moved forward till maximum height of the pulse is obtained.4      The sensitivity setting for the normal probe has to be done while keeping all other probes in Off position. Each main scale division.4.5m length having a simulated flaw at standard locations as shown in Fig.4. l.5    80� probe shall be connected to the socket available in the ultrasonic equipment. 4.4.2 Probes During ultrasonic examination of AT welded joints. 4. 4.         . The pulse shall appear moving from right to left. 2 MHz. Move the probe towards the 3mm dia hole drilled at the middle of the flange through in the AT weld and manipulate knobs to Obtain a 60% full screen height on the CRT. 4.            . 2 In the-case of lack of fusion. Similar testing shall be carried out on "C and 'U' region as shown in Fig.2.in/railwayboard/uploads/codesmanual/FWRATP/Thermic%20Process_Data. 6.gov. inclusions.htm[24-12-2013 12:25:49] .3   80� probe shall be placed on the flange at a distance of 180mm corresponding to position 'L' in Fig. moving signal shall be obtained while testing with 70� probe.2 such that ultrasonic waves are directed towards the weld.1 Any flaw1 signal obtained by normal probe of 40% height or more from head location shall be treated as a defective AT welded joint and any flaw signal obtained from the normal probe either from the web or the foot location shall also be a cause for rejection of the AT weld. In these cases also the criteria for rejection shall remain the same. A welded joint showing the moving signal of 40% or more of the full screen height shall be considered as a defective welded joint.MANUAL FOR FUSION WELDING OF RAILS XHE ALUMINO 5. The re-welded joints shall be scanned ultrasonically again with the same set of acceptance criteria to ensure freedom from any harmful defects. -. The probe shall thereafter be moved slowly in a zigzag pattern towards the weld. A welded joint showing a flaw echo of 40% vertical height or more with the stipulated gain setting shall be treated as a defective welded joint. Criteria for-defect classification 5. This execution shall be done by the contractor free of cost. re-welded and tested again. http://www. in the rail head.indianrailways. The position of onset of the signal and its corresponding range on the horizontal screen as well as their maximum amplitude shall be recorded. 5. blow holes etc. 5.  The defective joints based on the criteria mentioned at clause 5 shall not be allowed to remain in service and shall be cropped. 4. heat affected zones and parent metal of the rails in ac-cordance with IS:1500.2 Mechanical and Metallurgical tests on test welds 4. l shall be within ()20 HB for locations B and ( + )20 HB for locations C of the actual hardness of the parent rail.in/railwayboard/uploads/codesmanual/FWRATP/Thermic%20Process_Data. The welded joint shall be made as per the technique offered by the manufacturer. l shall be within +20 -0 HB of the hardness values of rail as shown in table 1.1 Two new rail pieces of same section and grade. " Method for Brinell Hardness test for steel ".indianrailways.2 Hardness test Brinell hardness test shall be' carried out at the welded zone. http://www.2. The average hardness number (of two readings) on each heat affected zone at locations shown as B1 and C in Fig. each approximately 750 mm long.htm[24-12-2013 12:25:49] .gov. The average hardness number (of two readings) determined for the weld metal at locations shown as "A' in Fig.MANUAL FOR FUSION WELDING OF RAILS XHE ALUMINO ANNEXURE-9 EXTRACTS FROM T-19-1994 4.1.2. shall be used to make test weld joint. The rail table and sides of rail head shall be finished to the geometrical tolerances specified in Clause 18. The test shall be done on the top surface of the head of the test weld with a ball of 10 mm dia and a test load of 3000 kg maintained for 10 sees. The load shall be gradually increased (rate of loading shall not exceed 2.indianrailways.in/railwayboard/uploads/codesmanual/FWRATP/Thermic%20Process_Data.1 The test weld shall be supported on cylindrical or semi-cylindrical supports having a distance of one metre between them from centre to centre.3.3  Transverse breaking load test: 4.5 t/sec) till rupture occurs. TABLE-2 http://www.htm[24-12-2013 12:25:49] .MANUAL FOR FUSION WELDING OF RAILS XHE ALUMINO Table-1   Type of rail   Average Hardness (BHN) 72 UTS rail  230 90 UTS rail  265  UTC Cr-Mn or Cr. The diameter of mandrel and the supports shall be between 30 to 50mm.Head Hard ened V  alloy steel rail Rail 310 365 4. The weld shall be at the centre of the span and loaded in such a manner that the foot of the rail is in tension.2.2.gov. The test weld shall withstand a minimum load and show corresponding minimum deflection as stipulated in Table-2 for different sections and types of rails. or in case where macro-etching is done on transverse section through the joint. exceeding total permissible area of defect shown in Table-3.2  If the fracture does not occur through weld.1 and 4.5 33.2 are found to be unsatisfactory.3 The fractured surface of the weld. These retests shall http://www.3.htm[24-12-2013 12:25:49] . The fractured surface shall also not show the presence of accretions or mirror like structure and shall be crystalline in appearance.in/railwayboard/uploads/codesmanual/FWRATP/Thermic%20Process_Data. 4.2. However.3.gov. a slice shall be cut transversely at the weld and etched in boiling 1:1 Hydrochloric acid for about 20  minutes to determine casting defects if any. The defects should not be interconnected and none of these shall extend upto the outer surface of the weld.indianrailways. However. the size of any individual defect shall not exceed 2mm diameter. TABLE-3 Area of permissible defects   Rail Section 60 75 90 52 60 R R R kg kg Permissible total area of defect (mm 2) 19.0 23.4 38.MANUAL FOR FUSION WELDING OF RAILS XHE ALUMINO 4.3.2. There shall not be any lack of fusion. the batch will stand rejected. shall not show defects such as blow holes. retests can be carried out at the manufacturer's request.4 4. porosity and inclusions etc.3 Retests 4.1  If the results of any of the tests referred to in clause 4.7 28. 3. the batch represented by the sample portions shall be accepted.2 on twice the original sample size.MANUAL FOR FUSION WELDING OF RAILS XHE ALUMINO be carried out as per para 4. the batch shall be rejected. 4.in/railwayboard/uploads/codesmanual/FWRATP/Thermic%20Process_Data.2  If the results of all the retest samples are satisfactory. If any sample fails to meet the requirements of any of the tests.gov.1 and 4.indianrailways.htm[24-12-2013 12:25:49] . ANNEXURE -10 MAJOR DEFECTS IN AT WELDING BECAUSE OF IMPROPER WELD EXECUTION http://www. htm[24-12-2013 12:25:49] .indianrailways.MANUAL FOR FUSION WELDING OF RAILS XHE ALUMINO http://www.gov.in/railwayboard/uploads/codesmanual/FWRATP/Thermic%20Process_Data. (b) & (c) http://www.indianrailways.in/railwayboard/uploads/codesmanual/FWRATP/Thermic%20Process_Data.gov.MANUAL FOR FUSION WELDING OF RAILS XHE ALUMINO Figures 3.htm[24-12-2013 12:25:49] .1 (a). MANUAL FOR FUSION WELDING OF RAILS XHE ALUMINO http://www.in/railwayboard/uploads/codesmanual/FWRATP/Thermic%20Process_Data.gov.htm[24-12-2013 12:25:49] .indianrailways. in/railwayboard/uploads/codesmanual/FWRATP/Thermic%20Process_Data.indianrailways.1 (a) .htm[24-12-2013 12:25:49] .2 http://www.1.7.gov. (b) & 4.MANUAL FOR FUSION WELDING OF RAILS XHE ALUMINO Figure 4. 7.1. 4.1 Figure 5.MANUAL FOR FUSION WELDING OF RAILS XHE ALUMINO Figure 5.htm[24-12-2013 12:25:49] .gov.in/railwayboard/uploads/codesmanual/FWRATP/Thermic%20Process_Data.indianrailways.2 http://www. gov.MANUAL FOR FUSION WELDING OF RAILS XHE ALUMINO http://www.in/railwayboard/uploads/codesmanual/FWRATP/Thermic%20Process_Data.indianrailways.htm[24-12-2013 12:25:49] . (Clause 7. AT welding by flame cutting/ gas cutting of rails specially for wide gap welding has been deleted and only sawing or abrasive disc cutting has been provided.in/railwayboard/uploads/codesmanual/FWRATP/Thermic%20Process_Data.7) 4.6) 12. Use of  880 grade portions for AT welding where grade 710 (72UTS) and Grade 880 (90UTS) rails form junctions in unavoidable circumstances has been specified (Clause 3.3(xi)). In case of secondary rail renewal. The composition of welding team has been revised keeping in view introduction of SKV welding and use of weld trimmer & rail profile grinder. As Conventional method of Alumino-Thremic (AT) welding has been discontinueed on Indian Railways except for 60R rails. Course of action to be adopted for welding of rails through approved portion manufacturer. In case of use of rail panels released from LWR/CWR territory. Welding parameters of AT welding techniques (As on 31. (Clause 3.indianrailways.2) 3.MANUAL FOR FUSION WELDING OF RAILS XHE ALUMINO SALIENT FEATURES 0F REVISED MANUAL FOR WELDING OF RAIL JOINTS BY THE  ALUMINO-THERMIC PROCESS (1999) 1.gov.1. (Clause 1. (Clause 4. Guarantee period and other provisions wherever required as provided in IRST-19-1994 have been included to update the manual in line with IRST-19-1994.3) 11. (Annexure-1) 11. As only grade 880 rails are being produced. cropping of rail ends so as to eliminate heat affected zone has been specified. 6. in case of large scale welding.97) including welding techniques under development for various approved firms have been laid down.2. In case of areas where severe corrosion is observed epoxy painting has been provided for. (Clause 3. Detailed instructions on painting of weld collar immediately after welding and also its in-service painting have been laid down. AT welding by end cropping so as to eliminate both bolt holes has been specified.htm[24-12-2013 12:25:49] . List of approved manufacturers of Rail profile weld grinder and Weld trimmer has been-included. Procedure to be adopted for use of portions beyond two years since the date of manufacture has also been laid down (Clause 4. (Annexure-10) 9. A para on Shelf life of portion1 has been included. accordingly the revised manual provides for only SKV AT welding. Provision of fixing an Aluminium strip with distinctive weld number on the web of rail by epoxy based adhesive has been laid down.12.3(viii)) 7. casual welding and welding forming part of turn-key projects have been outlined. A list of defects giving causes and preventive action to be taken to avoid the same has been briefly outlined. (Annexure-4)     http://www.(Annexure-3) 8.3(vi)) 10. (clause 5. (Clause 5. which brings out the importance of proper packing and storage of AT portions.5) 2.1) 5. labour contracting firms and departmental welders.