File: D:\Eigene Dateien\Kunden\DVS\Ri+Me\2207\2207-4\englisch\Jan_08\e2207-4.fm Erstellt am: 18.01.2005 Zuletzt geändert am: 29.01.2008 March 2008 DVS – DEUTSCHER VERBAND Welding of thermoplastics Extrusion FÜR SCHWEISSEN UND welding of pipes, piping parts and panels Technical Code VERWANDTE VERFAHREN E.V. Processes and requirements DVS 2207-4 Translation of the German version from april 2005 Contents: The technical code can be correspondingly applied to other materials and material modifications (e.g. electrically conductive). 1 Scope of application It is necessary to pay attention to supplementary instructions 2 Materials from the manufacturers of the semi-finished products. 3 General process description 3.1 Continuous welding process 3.2 Discontinuous welding process 3 General process description 4 Machine variants 4.1 Machine Variant I Extrusion welding is a manual or semi-automatic welding proc- 4.2 Machine Variant II ess. It is performed with a welding filler which consists of wire or 4.3 Machine Variant III granules and is melted and plastified in a plastifying system (ex- 5 Structural design, weld shapes and weld structure truder). A welding shoe shaped according to the weld geometry 6 Requirements serves to press the welding filler into the base material welding 6.1 Requirements on the welding machines and devices groove which is plastified with hot air as a rule. Other heat sourc- 6.2 Requirements on the welding shoes es or carriers may be, for example, a light ray or inert gases. The Reprinting and copying, even in the form of excerpts, only with the consent of the publisher 6.3 Requirements on the preheating material output capacity of the machines or devices determines 6.4 Requirements on the materials and their weldability the maximum weld dimensions and influences the welding 6.5 Requirements on the welders speed. The necessary joining pressure is generated by the 6.6 Requirements on the quality of the welded joints emerging material and the counterforce of the welder. 7 Start-up of the welding machines and setting of the welding parameters A distinction is made between the following processes: 8 Welding preparation – continuous welding process 8.1 Equipment – discontinuous welding process 8.2 Protective measures against environmental influences 9 Welding 9.1 Preparation of the joining faces 3.1 Continuous welding process 9.2 Tacking The plastified welding filler emerging from the manually or 9.3 Execution of a weld mechanically guided device or machine is continuously pressed 9.4 Finish machining of the welds into the also plastified welding groove by a welding shoe, Figs. 1, 9.5 Thermal after-treatment of the welds 3 and 4. 9.6 Welding record sheet 10 Testing of the welded joints 11 Safety instructions 12 Standards and technical codes which are also applicable Appendix 1: Brief instructions for the welding Normen-Download-Beuth-FINMA S.A. / Org.Techint-KdNr.7046465-LfNr.4612421001-2009-10-01 09:41 Appendix 2: Welding record sheet for the extrusion welding 1 Scope of application This technical code applies to the hot gas extrusion welding (hereinafter called extrusion welding) of pipes and panels in tank, apparatus and pipeline construction as well as during the manufacture of self-supporting collecting pans and of seals on concrete structures with thermoplastics. It describes the different processes, indicates the process limits and stipulates requirements for the quality assurance. Special instructions for the extrusion welding of sealing sheets in earthwork construction and water engineering are included in the DVS 2225-1 and DVS 2225-4 technical codes. Instructions for the extrusion welding of casing pipes can be found in the DVS 2207-5 technical code. 2 Materials This technical code applies to the materials specified in the DVS 2207-4 technical code, Supplement 1. Figure 1. Diagram for continuous welding with Machine Variant I. This publication has been drawn up by a group of experienced specialists working in an honorary capacity and its consideration as an important source of information is recommended. The user should always check to what extent the contents are applicable to his particular case and whether the version on hand is still valid. No liability can be accepted by the Deutscher Verband für Schweißen und verwandte Verfahren e.V., and those participating in the drawing up of the document. DVS, Technical Committee, Working Group “Joining of Plastics” Orders to: DVS-Verlag GmbH, P. O. Box 10 19 65, 40010 Düsseldorf, Germany, Phone: + 49(0)211/1591- 0, Telefax: + 49(0)211/1591-150 Page 2 to DVS 2207-4 In the case of manual welding, the feed speed results from the This process is predominantly used where confined space- volume of the emerging material flow and from the weld cross- related conditions or certain structural details exclude continuous section to be filled. In the case of welding with a feed system, the welding. welding speed must be adjusted to the material output. The welding zone is preheated by a hot gas fan attached to the welding head. 4 Machine variants 3.2 Discontinuous welding process The machines or devices consist of: For the welding, the plastified welding filler is extracted from the – the plastifying system (extruder) for the plastification of the extruder section by section with a corresponding quiver, is input welding filler inserted into welding groove plastified with a hot gas device and – the preheating system for the heating of the joining faces (as a is pressed in, shaped and smoothed with a press-on tool (Fig. 2). rule, hot air) – the welding head in order to accommodate the welding shoe and the preheating system – the welding shoe in order to input the extrudate into the welding groove and to shape the surface (alternative to the quiver and the press-on tool in the case of discontinuous welding) 4.1 Machine Variant I Machine or device type in which all the device components form one unit. As a rule, the welding filler is supplied to the device as round wire or, in the case of larger devices, also as granules, Fig. 1. 4.2 Machine Variant II The extruder and the welding head are structurally separate in the case of this machine type. For continuous welding, both machine parts are connected with each other by a heated hose for the welding filler, Fig. 3. For discontinuous welding, the extrudate is extracted directly from the extruder using replaceable material nozzles, Fig. 2. The machines of this type have a high output capacity but are primarily used in stationary operation due to their size. The welding filler is usually supplied to the device in granule form. 4.3 Machine Variant III The machines or devices consist of the welding wire intake station, the plastifying unit and the preheating system. The welding filler in wire form is transported into the heating chamber by the wire feed unit which inputs the plastified welding filler into Normen-Download-Beuth-FINMA S.A. / Org.Techint-KdNr.7046465-LfNr.4612421001-2009-10-01 09:41 the joining zone via the welding shoe, Fig. 4. As a rule, the devices are smaller and easier to handle than Machine Variants I Figure 2. Diagram for discontinuous welding with Machine Variant II. and II but also have a lower output capacity. Figure 3. Diagram for continuous welding with Machine Variant II. Page 3 to DVS 2207-4 For materials others than those listed in Appendix 1, it may be necessary to choose different weld shapes and weld preparation angles. Desination Sheme Symbol V- seam V-seam V Double-V-seam Double-V-seam (X-seam) (X-seam) X Double-HV- Double-HV-seam seam (K-butt) (K- butt) K Fillet Fillet Figure 4. Diagram for continuous welding with Machine Variant III. 5 Structural design, weld shapes and weld structure The DVS 2205 ff. technical codes apply to the structure of the components and the DVS 2205-3 technical code to the design of the welds (the supplements to the respective technical codes are Figure 5. Examples of weld shapes and weld symbols. also applicable). In particular, attention must be paid to the following: Depth of seams s (mm) – Crossing welds must be in a staggered arrangement. V- and double V-seams – The distance between the welds should be about three times HV-seams the width of the top layer but min. 50 mm. – In the case of butt joints, it is necessary to match the work- piece thicknesses of connecting ends with different thick- nesses (DVS 2205). – A weld shape which guarantees that the cross-section of the thinner joining part in each case can be connected completely (e.g. T-joint with a single-bevel butt weld) should be chosen in Angle of seam opering (’’) Normen-Download-Beuth-FINMA S.A. / Org.Techint-KdNr.7046465-LfNr.4612421001-2009-10-01 09:41 the case of accessibility from one side only. a) Continuous welding DIN EN 22553 applies to the designation and graphical and symbolic representation of the welds. Depth of seams s (mm) The most important weld shapes are single-V, double-V, single- bevel and double-bevel butt welds as well as fillet welds. HV-seam V- and double V-seams Examples of the execution of welds as well as their symbolic representation on fabrication drawings are shown on Fig. 5. As a rule, the welds are manufactured in a single layer or, in special cases, in multiple layers. In order to reduce the weld volume and because of the more uniform distribution of the residual welding stresses, the welds should, if at all possible, be executed on both sides or with a Angle of seam (’’) backing layer (double-V butt weld, fillet weld and double-bevel butt weld). b) Descontinuous welding The material input into the welding grooves should be minimised because of the shrinkage stresses arising during the cooling of Figure 6. Recommended weld preparation angles for PE-HD and PP in the case of single-V and single-bevel butt welds depending on the welds. It is therefore recommendable to change the weld the weld depth and the welding process (for other materials, it preparation angle according to the joining part thickness, Fig. 6. may be necessary to choose different weld preparation angles). The residual root opening should be max. 1 mm and full- penetration welding must be ensured. 6 Requirements The root gap should not exceed 2 mm in the continuous welding process and 4 mm in the discontinuous welding process. If the 6.1 Requirements on the welding machines and devices root gap width cannot be complied with for structural or design- related reasons, appropriate measures must be taken (e.g. using The welding machines and the welding devices must be in a a backing strip). functioning condition. Their condition and good working order Page 4 to DVS 2207-4 must be checked regularly (e.g. by means of monitoring by the The weld overlap ∆b should be more than or equal to 0.2 times manufacturers). the joining part thickness but it should be min. 3 mm. The output quantity and the preheating capacity must be The weld reinforcement ∆s should be 0.1 - 0.2 times the joining adjusted to the welding job. part thickness. Special requirements on the welding machines and the welding The "nose" located on the front part prevents the material from devices are described in Supplement 2 to this technical code. flowing ahead, is a prerequisite for the generation of the necessary joining pressure and supports the forward movement 6.2 Requirements on the welding shoes of the welding device. It must correspond to the welding groove The joining pressure necessary for the welding is applied to the shape but must not touch the welding groove faces during the joining faces with the welding shoe via the welding filler. At the welding. same time, the welding shoe shapes and smooths the weld The gap between the nose and the weld sidewalls should be surface. 1 - 3 mm depending on the weld thickness. Therefore, the welding shoes must correspond to the welding job, The undercut on the contact surfaces prevents molten base must be structurally adjusted to the respective weld shapes and material from being pushed away. thicknesses (Fig. 7), must have smooth, anti-adhesive surfaces and must be sufficiently temperature-resistant. When press-on tools are used for discontinuous welding, the above stipulations are applicable correspondingly. Table 1. Guide values for welding shoe dimensions. a) Welding shoe for single-V welds Seam depth s for V-seams s Pressing length LA (mm) (mm) to 15 35 > 15 to 20 45 > 20 to 30 55 6.3 Requirements on the preheating b) Welding shoe for The preheating must guarantee that the joining faces and the fillet welds areas of the weld overlap, Fig. 8, are sufficiently plastified even Normen-Download-Beuth-FINMA S.A. / Org.Techint-KdNr.7046465-LfNr.4612421001-2009-10-01 09:41 when the welding groove geometry changes. The welding shoes and the preheating (nozzle geometry, air volume and hot gas temperature) must be coordinated. 6.4 Requirements on the materials and their weldability Semi-finished products and welding fillers (wire and granules) must be suitable for extrusion welding. One prerequisite for welded joints which should meet the requirements according to DVS 2203 is the use of a welding filler of the same type as the base material but at least of a similar type. For the semi-crystalline materials (such as PE, PP and PVDF), reference is made to the melt index as a characteristic parameter for the weldability. If the melt index (MFR) values of the welding partners are within the permissible melt index ranges in DVS 2207-1, -11 and -15, weldability may be assumed in general. If two semi-finished products in different MFR groups from these ranges are to be welded with each other, it is Figure 7. Representations of welding shoe designs. necessary to choose a welding filler whose MFR value is between that of the combination of semi-finished products. For As a rule, they are made of polytetrafluoroethylene (PTFE). This PE-HD, PP and PVDF, attention must be paid to the instructions material possesses the specified properties and is easy to in the scope of application of the DVS 2207-1, 2207-11 and machine. 2207-15 technical codes. If the melt index is outside the authorised ranges in the specified technical codes, the welding The lengths of the press-on zone and the smoothing surface evidence according to DVS 2203-4 must be provided in the should not be less than the minimum lengths specified in Table 1. tensile creep test. This ensures that the joining pressure acts during a minimum time and that the necessary bond can thus be produced The following applies to amorphous materials such as PVC: throughout the joining area (especially the weld root and the weld "Only semi-finished products of the same moulding material type sidewalls). are weldable." Page 5 to DVS 2207-4 The semi-finished products and the welding fillers must be If the material is changed, it must be ensured, by means of marked correspondingly and unmistakably (in the case of cleaning or extruding-out, that all the material in the welding welding fillers, on the packaging). extruder is replaced. If necessary, the nozzles must be changed. In the case of Machine Variant II, the hose must always be Only semi-finished products with stipulated quality requirements changed as well. It is recommended not to use the same extruder should be welded (e.g. works certificate according to DIN EN for different materials in practice. 10204). The welding filler must be dry. If necessary, it must be dried The welding fillers must meet the requirements according to the before use (e.g. several hours in an exhaust air oven at DVS 2211 technical code and DIN EN 12943. temperatures of approx. 60 - 80°C). Attention must be paid to the The base and filler materials must be available in a flawless information from the welding filler manufacturer. processing condition and must be dry and clean. While the machine is running, the required material temperature If there are any doubts that the semi-finished products and/or the is checked directly at the material outlet in the middle of the welding filler are similar (e.g. due to a lack of labelling) or if any strand using the prick sensor of a quick-display temperature material changes are to be feared due to: gauge. – improper storage The control measurement of the hot air temperature is taken in – low joining part temperatures the hot air nozzle between the nozzle outlet plane and a depth of - soiling 5 mm using a precision probe with a diameter of approx. 1 mm – ageing (see the instructions in DVS 2207-4, Supplement 2). – operating influences (media or temperatures) The stipulated air volume must be checked in the case of devices it is necessary to establish the weldability by means of tests on with an external air supply. It is necessary to ensure the flawless trial welds. Agreement must be reached with regard to the type function of devices with an internal air supply. and scope of the tests. Instructions about this are given in the The material and hot gas temperatures must be checked DVS 2203-1 and 2201-2 technical codes. immediately before the beginning of the welding. Repeat checks are recommendable in the case of a welding job lasting a longer 6.5 Requirements on the welders time or after interruptions in the work. Hot gas extrusion welding is a welding process for which not only All the measurements must be taken with regularly checked comprehensive knowledge with regard to the materials to be measuring instruments (according to DVS 2207-4, Supplement welded and to the handling of the machines and devices but also 2) and must be documented (Appendix 2). high skills in the execution are prerequisites. The welder must have passed a qualification test according to the DVS 2212-1 technical code, Qualification Test Group II, and 8 Welding preparation must possess a valid test certificate. The welding grooves of the joining parts are prepared according 6.6 Requirements on the quality of the welded joints to Section 5. If the welds are executed properly according to this technical It must be guaranteed that the welding head of the machine or code, those minimum requirements on the quality of the welds device has sufficient accessibility to the joining faces. Welding which are specified in the DVS 2203-1 technical code (welding out of position should be avoided or minimised because of the factors and bending angles) are sure to be met. With regard to required counterpressure to be applied by the welder. It must be the application in question, to statutory stipulations if needed ensured that the welder is not hindered during the welding as a (Water Management Act, Pressure Device Directive etc.) and to result of the necessary readjustment of the connecting cables the necessary dimensioning, the customer and the manufacturer and hoses as well as of the welding filler. should agree on the corresponding requirements on the Normen-Download-Beuth-FINMA S.A. / Org.Techint-KdNr.7046465-LfNr.4612421001-2009-10-01 09:41 component and on the welded joints and should stipulate these. 8.1 Equipment Instructions and criteria for stipulating the quality are described in The following equipment constitutes the minimum requirements the DVS 2202-1 technical code. The inclusion of the weld quality for the proper execution of the welded joints: in the component calculation is described in the DVS 2205-1 to -5 technical codes. – hot gas extrusion welding device according to the welding job and this technical code If necessary, the evidence of the demanded quality may be provided within the framework of establishing its suitability on trial – welding shoes according to the welding job welds with reference to DVS 2212-1. This applies especially to – flow meter for welding gas materials for which no requirements have yet been stipulated in –- temperature gauge according to DVS 2207-4, Supplement 2 the specified technical codes (e.g. PVC-C). – suitable measuring instruments for checking the misalignment, the diameter and the thickness 7 Start-up of the welding machines and setting of the – suitable storage space for the devices welding parameters – scraper and scraper blade The start-up is carried out according to the operating instructions – personal protective equipment from the machine manufacturer. – dust protection for the welding wire Extrudate residues in the extruder, at the outlet opening as well as, if applicable, in the transport hose must be melted completely – sufficient lighting before the extrusion drive is switched on. – protective measures against weathering influences (see In order to avoid the use of thermally predamaged welding filler, Section 8.2) the reheated melt should be extruded out completely before the – special cleaning agent (not swelling, dissolving or containing beginning of the welding. This also applies to longer interruptions greasy) and non-fraying rags in the work. The maximum dwell times are dependent on the – welding parameters according to DVS 2207-4, Supplement 1 material in question (in the case of PE-HD and PP, approx. and/or instructions from the manufacturers of the semi-finished 5 min). In the case of thermally sensitive materials such as PVC products and PVDF, it is to be recommended to keep the extruder running during the interruption in the welding. – welding record sheet according to Appendix 2 Page 6 to DVS 2207-4 8.2 Protective measures against environmental influences The welder must ensure that the molten base material at the weld The ambient conditions may exert a fundamental influence on the sidewalls is not pushed off by the welding shoe nose. welding operation and thus on the quality of the joint. Therefore, In the case of restarts and at the end of circumferential welds, it is attention must be paid to the following: necessary to diagonally machine off the already executed ends – The welding area must be protected from unfavourable of the weld. weathering influences (such as moisture, formation of condensation water, wind, draughts and temperatures below + 5°C). – If it is ensured, by taking suitable measures (e.g. preheating, tenting or heating), that a semi-finished product temperature sufficient for the welding can be complied with, the welding may be carried out at any outdoor temperature – provided that the dexterity of the welder is not hindered. If necessary, additional evidence must be provided by manufacturing and testing trial welds in the existing conditions. – In the case of non-uniformly tempered joining parts (e.g. due to solar radiation on one side, in the case of different storage conditions etc.), the temperatures must be equalised before the welding. 9 Welding Figure 8. Example of a single-V butt weld with representation of the mel- 9.1 Preparation of the joining faces ting zones and the weld overlap. The joining faces must not be damaged, oxidised or soiled. In order to avoid the excessively rapid cooling of the top layer Therefore, they and the adjacent weld overlap areas must be and the resulting formation of shrinkage cavities, it is subjected to chip-producing machining immediately before the recommended to cover the extrusion weld immediately after the welding. welding. Chip-producing tools such as scrapers, scraper blades, milling If multi-layer welds are necessary, the cooled weld sidewalls and cutters and saws are suitable. Grinding tools are only permissible surfaces of the already welded layers must be subjected to chip- if it is possible to exclude the soiling caused by inputting producing machining. abrasives and the overheating of the surfaces. Design-induced modifications to the weld geometry in the weld Especially in the case of joining parts which have been exposed path (e.g. in the case of segment bends and branches) demand to the influence of UV or media for a long time, the damaged particularly careful guidance of the welding shoe. If necessary, layer may be so deep that the residual wall thickness, including the welding shoe must be changed. the static requirements, must be checked after the machining-off. In the case of semi-automatic and fully automatic systems and If the joining faces must be cleaned, it is necessary to use special facilities for extrusion welding, the welding parameters (the cleaning agents which do not contain any grease. material output, the preheating and the welding speed) must be coordinated and must be set correspondingly. 9.2 Tacking It is recommended to manufacture trial welds. Tacking serves to fix the joining parts in their planned positions in relation to each other in order to exclude any changes in the In the case of discontinuous welding, the welding filler is extracted from the extruder with the quiver and is inserted into Normen-Download-Beuth-FINMA S.A. / Org.Techint-KdNr.7046465-LfNr.4612421001-2009-10-01 09:41 positions of the joining parts during the welding. Tacking is usually carried out by means of the partial or continuous high- the plastified welding groove section by section. The joining speed hot gas welding of a root layer with a welding filler wire. pressure is applied with the press-on tool across all the cross- sectional areas of the weld (central and edge areas) in several 9.3 Execution of a weld operations and the weld surface is shaped at the same time. Before the beginning of the welding operation, the welding shoe 9.4 Finish machining of the welds must be heated up (e.g. using a baffle plate) since welding with a cold welding shoe results in a rough and uneven weld surface. Subject to corresponding welding shoe formation and machine This also applies to press-on tools in the case of discontinuous guidance during the welding, finish machining of the welds is not welding. necessary (in this respect, see also DVS 2202-1, Table 5). The start of the weld is preheated and completely melted with hot It is imperative to remove the lateral flow which may be pressed air. Immediately before the welding shoe is placed on the welding through under the contact surfaces of the welding shoe. groove, the welding filler which has already emerged is removed Reinforced weld beads and reinforced weld roots must be from the welding shoe opening. After the filling of the groove, the machined off correspondingly without any notches. material pressure builds up due to the counterpressure generat- The weld may only be machined off after sufficient cooling. ed by the welder and the forward movement of the welding shoe begins. 9.5 Thermal after-treatment of the welds In the case of manual welding, the welding speed is determined Residual welding stresses can be reduced by means of by the material output of the extruder and the size of the weld tempering. The tempering conditions depend on the material and cross-section. the component. Attention must be paid to the information from The preheating of the joining parts must be adjusted to the the manufacturers of the semi-finished products. welding speed in such a way that the base material is plastified down to a depth of 0.5 - 1 mm. 9.6 Welding record sheet The plastification zone must be wider than the weld width. Guide The completely filled-in welding record sheet documents the value: weld width + 2 • (0.2 • joining part thickness s) (see Fig. welding conditions and parameters amongst other details. It is 8). the foundation for the evaluation of the weld quality by the The melting depth is checked directly in front of the welding shoe. welding supervisor (compare DVS 2213, specimen record sheet This may be carried out with a thin, blunt tool. in Appendix 2). Page 7 to DVS 2207-4 10 Testing of the welded joints A distinction is made between non-destructive and destructive test procedures. They are listed in Table 2 "Possible test procedures" for the most frequent weld shapes. Table 2. Usual test procedures for extrusion welds, applicability and requirements. Non-destructive tests Visual inspection of Visual inspection, according to DVS 2202-1 and 2206. The evaluation group must be stipulated in each the undestroyed weld individual case. (external findings) Leak test with a partial Using suitable vacuum bell jars and a foaming liquid; the test conditions must be stipulated in each vacuum individual case. Usual test pressure: -0.4 bar to -0.6 bar. Leak test with electric The type of test device (with or without an antipole) and the test voltage must be stipulated in each high voltage individual case. Test technique according to DVS 2206, Section 3.3.1.4. Radiographic test Applicable; statement with the number, positions, shapes and sizes of pores, shrinkage cavities and comparable defects possible. Test technique according to DVS 2206, Section 3.5. Ultrasonic test Applicable to PE-HD, with restrictions to PP (statement about voids, not about quality). Test technique according to DVS 2206, Section 3.4. Pressure test Application usually for pipelines; test conditions according to the Pressure Device Directive. Test execution according to DVS 2210-1, Supplement 2 and DIN 4279-7. Meaningfulness: leak tightness, experimental evidence of the operational safety. Destructive tests Visual inspection of Formation of the executed weld cross-section (weld geometry), internal findings according to DVS 2202-1, the weld cross-section Tables 4 and 5. Fracture pattern of the weld destroyed in the tensile test or in the technological bending test. Tensile test Execution according to DVS 2203-2: short-time tensile welding factor; DVS 2203-4: creep rupture welding factor; minimum requirements according to DVS 2203-1. Test not applicable to fillet and single-bevel butt welds. Technological bending Execution according to DVS 2203-5, minimum requirements (bending angle) according to DVS 2203-1. test Test not applicable to fillet and single-bevel butt welds. The visual inspection concentrates, in particular, on the weld In explosion-protected areas, attention must be paid to the valid shape, the notch-free surfaces and peripheral zones, the safety regulations with regard to the welding work and any optimum weld filling, the full weld penetration on the root side and measures which may be necessary must be agreed on with the the joining part misalignment. safety officer responsible; in this respect, see the Operational Safety Ordinance (BetrSichV). Normen-Download-Beuth-FINMA S.A. / Org.Techint-KdNr.7046465-LfNr.4612421001-2009-10-01 09:41 With ultrasonic and X-ray testing (see the DVS 2206 technical code), flaws can be detected in the interior of the welds without any destruction. However, on their own, they do not provide a 12 Standards and technical codes which are also sufficient indication of the quality of the welded joint. Moreover, applicable the utilisation possibilities of these test procedures are limited with regard to the weld geometry and the weld thickness. DIN 1910-3 Welding of plastics – Processes For the designation and evaluation of defects, reference is made DIN V 4279-7 Internal pressure testing of pressure piping for to the DVS 2202-1 technical code. (preliminary water – Pressure pipes made of low-density standard) polyethylene PE-LD, pressure pipes made of It is necessary to stipulate the type and scope of the tests to be high-density polyethylene PE-HD (PE 80 and performed in each individual case. PE 100), pressure pipes made of cross-linked Material-specific tests are indicated in DVS 2201-1 and general polyethylene PE-X and pressure pipes made of tests such as dimensional accuracy or surface assessment in unplasticised polyvinyl chloride PVC-U DVS 2206. DIN 16960-1 Welding of thermoplastics – Principles DIN 32502 Defects in welded joints made of plastics – Classification, designations and explanations 11 Safety instructions DIN EN 12943 Welding fillers for thermoplastics – Scope of Hazardous decomposition products and health-endangering application, marking, requirements and testing fumes result from the overheating of some materials (such as. DIN EN ISO Plastics – Code letters and codes – Part 1: Base PVC, PVDF and E-CTFE) or already develop during the welding 1043-1 polymers and their particular properties of other materials (such as FEP, MFA, PFA and PTFE). On the DVS 2201-2 Testing of semi-finished products made of basis of the DIN safety data sheets to be submitted by the thermoplastics – Weldability – Test procedures manufacturer, the contractor must elaborate operating – Requirements instructions which comply with Section 20 of the Hazardous Substances Ordinance (GefStoffV) and indicate all the potential DVS 2202-1 Defects in welded joints between thermoplastics hazards and necessary protective measures. It may be – Characteristics, description and evaluation necessary to take further specific protective measures in each DVS 2203 Testing of welded joints between panels and individual case. pipes made of thermoplastics Page 8 to DVS 2207-4 -1 Test procedures – Requirements DVS 2207-4, Welding of thermoplastics – Extrusion welding -2 Tensile test Supplement 2 of pipes, piping parts and panels – Requirements on the welding machines and -4 Tensile creep test welding devices -5 Technological bending test DVS 2207-11 Welding of thermoplastics – Heated tool welding DVS 2205 Calculation of tanks and apparatus made of of pipes, piping parts and panels made of PP thermoplastics DVS 2207-15 Welding of thermoplastics – Heated tool welding -3 Welded joints of pipes, piping parts and panels made of PVDF -4 Flanged joints DVS 2210-1 Industrial piping made of thermoplastics – -5 Rectangular tanks Planning and execution – Overground pipe systems DVS 2206 Testing of components and structures made of thermoplastics DVS 2211 Welding of thermoplastics – Welding fillers – Marking, requirements and tests DVS 2207-1 Welding of thermoplastics – Heated tool welding of pipes, piping parts and panels made of DVS 2212-1 Qualification testing of plastics welders – PE-HD Qualification Test Groups I and II – Hot gas welding with the torch separate from the filler DVS 2207-3, Welding of thermoplastics – High-speed hot gas rod, high-speed hot gas welding, heated tool Supplement 1 welding and hot gas welding with the torch butt welding, sleeve welding with an separate from the filler rod of pipes, piping parts incorporated electric heating element, heated and panels – Welding parameters tool sleeve welding and hot gas extrusion DVS 2207-3, Welding of thermoplastics – High-speed hot gas welding Supplement 2 welding and hot gas welding with the torch DVS 2225 Joining of sealing sheets made of polymer separate from the filler rod of pipes, piping parts materials in earthwork construction and water and panels – Requirements on the welding engineering devices and accessories DVS 2207-4, Welding of thermoplastics – Extrusion welding DIN standards can be obtained from Beuth Verlag, Berlin and Supplement 1 of pipes, piping parts and panels – Welding DVS technical codes from Verlag für Schweißen und verwandte parameters Verfahren DVS-Verlag GmbH, Düsseldorf. Normen-Download-Beuth-FINMA S.A. / Org.Techint-KdNr.7046465-LfNr.4612421001-2009-10-01 09:41 Page 9 to DVS 2207-4 Appendix 1: Brief instructions for the welding 4. Prepare the welds and the joining faces (Section 9.1) – check, stipulate and manufacture the weld geometry and the 1. Put together the welding equipment (Section 8.1) weld shape – valid welder's certificate – remove the oxide layer from the joining faces by means of – hot gas extrusion welding device corresponding to the welding chip-producing machining job, including the operating instructions 5. Tack the joining parts (Section 9.2) – possibly hot gas welding device for tacking the joining parts – execute a partial or continuous root layer with a hot gas – welding shoes according to the weld shape welding device – flow meter for welding gas 6. Start up and prepare the welding extruder (Section 7) – temperature gauge with sensors for measuring the hot gas and – check the supply lines (electricity and air) for any possible the extrudate as well as the temperature of the semi-finished hindrances to the welding operation products – connect and start the extruder according to the operating – suitable measuring instruments for checking the misalignment, instructions the diameter and the thickness – select, adjust and assemble the welding shoe and the hot gas – storage space for the devices nozzle according to the weld geometry and the weld shape – scraper and scraper blade – extrude the reheated welding filler out of the cylinder – personal protective equipment – set and check the parameters (Appendix 1) – dust protection for the welding wire – preheat the welding shoe – cleaning agent 7. Welding (Section 9.3) – Supplement 1: Welding parameters –- check that the base material is sufficiently plastified (e.g. by – Appendix 2: Welding record sheet pricking it with a blunt tool) – special welding instructions – check the welding speed and monitor the uniformity 2. Check the working conditions and plan the measures – continuously check the guidance of the welding extruder and (Section 8.2) make any corrections needed – accessibility – if necessary, prevent any excessively rapid cooling of the weld – sufficient lighting surface by covering it – protective tent – bevel the ends of the welds before restarts – heating – protect the welding filler from contaminations 3. Check the weldability (Section 6.4) 8. Finish-machine the weld (Section 9.4) – on the semi-finished products and welding fillers, check that – let welded parts cool down sufficiently before unclamping them the information from the manufacturers is correct and subjecting them to loads – check the condition and cleanness of the joining partners and – machine off the lateral weld flow and the weld reinforcements possibly clean them 9. Compile the welding record sheet (Section 9.6) – if necessary, check the weldability of the joining partners by means of build-up welding according to DVS 2201-2 or trial –- fill in the welding record sheet (Appendix 2) and carry out the Normen-Download-Beuth-FINMA S.A. / Org.Techint-KdNr.7046465-LfNr.4612421001-2009-10-01 09:41 welds visual inspection according to DVS 2202-1 Page 10 to DVS 2207-4 Appendix 2: Welding record sheet for the extrusion welding Extrusion welding of panels and pipes Company logo Project: Project no.: Protective Weathering measures Drawing no.: Base material (manufacturer, type, batch, date): 1 = Sunny 1 = None Welder: Welding filler (manufacturer, type, batch, date): 2 = Dry 2 = Screen Welding certificate no.: / valid untel Welding machine, make, tpye: 3 = Precipita- 3 = Tent tion Welding supervisor (3): Year of construction / last machine examination: Process variant according to DVS 2207-4: 4 = Wind 4 = Heating Date Weld no. Joining part Weld shape Welding Air volume Material Hot gas Welding Ambient tem- Semi-finis- Weathering Protective Visual thickness (symbol) shoe no. temperature temperature speed perature hed product (code no.) measures evaluation temperature (code no.) mm l/min C (1) C (2) cm/min C C o o o o Normen-Download-Beuth-FINMA S.A. / Org.Techint-KdNr.7046465-LfNr.4612421001-2009-10-01 09:41 (1) Measured with a pricking thermometer at the extrudate outlet of the welding machine / welding device Remarks: e.g. less favourable conditions (2) Measured in the middle of the nozzle outlet opening, 5 mm in the nozzle (3) E.g. specialist for plastics welding according to DVS 2213 Date / signature of the welder Date / signature of the welding supervisor