Sandvik Sanicro® 38/4L7* Composite tube for Black Liquor Recover y and other boilers Product and product history UP RT96 TA19 Composite tubes consist of an external layer of stainless steel, metallurgically bonded to an internal load carrying layer of normal boiler tube material. All composite tubes are subject to 100% ultrasonic examination to check for inner and outer surface defects and to verify the metallurgical bond. Sandvik has been producing composite tubes since the early 1970’s. The biggest application is furnace walls in recovery boilers for the pulp and paper industry. More than 1.5 million metres in 3R12/4L7 have been supplied to more than 250 recovery boilers worldwide. S Sandvik Sanicro 38/4L7 for more severe conditions Figure 1. First complete floor of Sanicro 38/4L7, installed in a recovery boiler, delivered by Tampella Power to Metsä-Rauma Mills, Finland in 1996. By courtesy of Kvaerner Pulping, Finland Grades Outer component Sandvik Sanicro 38 Type UNS N08825, Mod. Alloy 825, W.-Nr. 2.4858 Chemical composition (nominal), % C max. Si max. Mn Cr Ni Mo Cu Ti 0.030 0.5 0.8 20 38.5 2.6 1.7 0.8 Type ASME SA-210 A1, EN P265GH, EN 1.0425, W.-Nr. 1.0405, St 45.8.III, SS 1435. Chemical composition (nominal), % C max. Si max. Mn P max. S max. 0.18 0.3 0.7 0.030 0.030 Sandvik spec. 7-1-0009 ASME Code Section 1 and Section II VD-TÜV Werkstoffblatt 541.03.2001 TÜV Wien Werkstoffblatt 140 Dimensions and tolerances Stock standard sizes Outside diameter Total minimum wall thickness Thickness of stainless component mm mm inch mm inch Minimum thickness of carbon steel component mm inch 5.08 6.53 6.58 .200 .257 .259 1.42 1.82 1.86 .056 .072 .073 3.66 .144 4.71 .185 4.72 .186 inch 50.8 2 63.5 2.5 76.2 3 Other dimensions can be supplied on request. Inner component Sandvik 4L7 Specifications Sandvik has developed a more resistant composite tube product, Sandvik Sanicro 38/4L7*, mainly intended for the floors of recovery boilers. This product has considerably improved corrosion resistance. It is more resistant to SCC, has better fatigue strength and improved structural stability. See pages 3 and 4. Tolerances Permissible variations in O.D. and wall thickness Outside diameter ± 0.5% Total wall thickness +15/-0% Thickness of stainless ± 0.40 mm (0.016 inch) steel component The thickness of the stainless steel component is checked by testing the entire length of each tube. heat input 1) kJ/mm (kJ/in) Max. dilution should be minimised. as this may result in hot cracking or the formation of brittle weld structures. during fin welding (carbon steel fin). shop welding must be carried out with a machine specially designed for the purpose. in order to avoid hot cracking or brittle weld metal structures.1E 7018 Sandvik 27.5 (63) 2. °C (°F) Carbon Steel (No. Figure 2.039–0.4 E 383-16 Sandvik Sanicro 60 AWS SFA5. with tubes linked by fins (see figs. 6857 50˚ a t d5/32" (d4 mm) t >5/32" (>4 mm) a = 0.18: ER 70 S-6 Matching filler AWS A5. Thick fins should be bevelled. Edge preparation of fins.12" (3 mm) Sanicro 38 Sanicro 38 3 2 1 0–0. if the stainless peel off is increased. a local melting may occur. 2) Panel welding Two types of panel are normally fabricated: either tangential panels. 4 and 5). Sanicro 60 for waste incineration boilers. in order to minimise the amount of fin material in the weld (see fig.08" (0–2 mm) too much heat.LCuR AWS A5. 3) are recommended. In general.14 ER NiCrMo-3 2) Sandvik 27. The melting point of the bonding zone is lower than the melting point of the stainless steel. MIG (GMAW/131) or SAW (12) are suitable methods for fabrication of finned panels.08" (0–2 mm) 0–0. Welding sequence.4. Furthermore. Therefore. interpass temp.5 (63) 1 (25) 1 (25) 1 (25) 1 (25) – – 150 100 150 100 (300) (212) (300) (212) 1) A higher heat input may be applied for the root. The weld should not penetrate the stainless steel layer of the composite tube.31. . See table 1. The choice of filler metal depends upon the fin material used. 3) MMA is recommended for manual welding to ensure low penetration and maintenance of the carbon steel cross section of the butt weld. tubes joined directly by a weld. or finned panels.4. Load carrier Unalloyed filler metal for root and filler runs Load carrier 7062 7061 Figure 3. 2 Figure 5 .and filler runs. in order to obtain the optimum corrosion resistance and mechanical properties of the welded joints. The impurity level in carbon steel fin materials should be considered.9 ER 383 Sandvik Sanicro 60 AWS A5. A basic flux should be used in SAW (12).059" (1–1.Welding Butt welding Butt welding of composite tubes must be carried out in such a manner that dilution of the components is kept under control. if the bonding zone is exposed to Austenitic filler metal for top run 60° > 0. excessive dilution of the fully austenitic stainless steel filler metal.LCu AWS A5. 2) and welding sequences (fig.31. Welded finned panel. and. Table 1. Filler metals and welding methods for butt welding. in order to minimise susceptibility to hot cracking.11 E NiCrMo-3 2) 2. may also lead to hot cracking or a brittle weld structure.5 mm) Figure 4. In both cases. 3) TIG/MIG MMA TIG/MIG TIG/MIG MMA 3) MMA 3) Matching filler AWS A5. 1 – 2) Stainless Steel (No. the following edge preparation (fig. 4). Pass Welding method Filler metal options specification Max. Edge preparation. see fig.0 15.5 20.Improved corrosion resistance Physical properties Density g/cm3 lb/in3 4L7 Sanicro 38 7.5. Sandvik Sanicro 38.9 14.4 13.5 18 18.2 0. 1. 6 shows isocorrosion in H2SO4 for Sandvik Sanicro 38 and AISI 316L.5 26.257" min).65 (.7 18.4 7. (2. weight-% Figure 6. mean values in temperature ranges (x10-6) Per °C Temperature.5 x 6.5 27.5 8.5 11 18 19 20.20 (8) 0.3 3R12 16.˚C (˚F) 110 (230) Thermal expansion/conductivity The composite tube values below have been calculated on a typical size.4 San 38 14. see fig.28 0.5 x 0.7 8.1 8.4 7.0 3R12 9.3 3R12/ 4L7 San 38/ 4L7 13. °C 4L7 20 100 300 500 46 48 46 42 3R12 15 16 20 23 San 38 11 12 16 19 3R12/ 4L7 San 38/ 4L7 31 33 35 35 25 27 31 32 20 30 40 50 60 70 % Ni Figure 7.8 8.8 13. Sandvik Sanicro 38 is more resistant to stress corrosion cracking induced chiefly by the presence of chlorides.1 9.6 9.3 8.6 14.5 9.9 15.2 14. compared to 10.6 San 38/ 4L7 7.8 8.8 10.8 13.1 7.5 14. pH = 6.5 7 9.10 (4) 0. 8.8 7.257") min Total = 6. Corrosion rate.25 (10) = Alloys with 17–21% Cr = Alloys with 26–28% Cr 0.192") min Sanicro 38 = 1.5 3R12/ 4L7 7.3 12.82 (.072") ave 4L7 = 4.5 7.5 12 13 6.6 15.53 mm min.065") ave 4L7 = 4. Isocorrosion diagram for Sandvik Sanicro 38 and AISI 316L (in sulphuric acid).4 8.257") min Thermal expansion.1 mm/year (4 mpy). Corrosion rate of FeCrNi-alloys as a function of Ni content in 28% NaOH plus 8% NaCl at 99°C (210°F).3 12.9 14.5 ���� ��� ��� ���� ��� ��� � ��� ��� ��� ��� ��� �������������� �������� �� ����� ������� Figure 8.5 15.1 7.-Nr.185") min Total = 6. °F 86 – 200 86 – 400 86 – 600 86 – 800 86 – 1000 4L7 6. dimension 63. is alloyed with 38% nickel.3 14.1 15. mm/year Per °F Temperature.0 8.30 The outer component. Temperature. Results of stress corrosion tests in 40% CaCl2 at 100°C (212°F).3 13.53 (.4306). 3 .0 18.1 0.71 (.5 14. °F 4L7 3R12 San 38 3R12/ 4L7 San 38/ 4L7 68 200 600 900 26.15 (6) 0. Fig.5 17.05 (2) Thermal conductivity 10 W/m °C Temperature. ���� �� ��������� � ��� ����� ��� ������� �� ��� ��� Btu/ft h °F Temperature. The curves represent a corrosion rate of 0.5 24. The higher nickel content gives Sandvik Sanicro 38 a substantially higher resistance to sodium hydroxide induced corrosion.5% for 3R12 (TP 304L/W.0 14.9 8. 3R12 = 1.6 6860b 90 (195) Sanicro 38 70 (160) 50 (120) AISI 316L 30 (85) AISI 316L 20 40 60 100 80 H2SO4.53 (.9 8.2 17.1 10.4 7. 7.1 8.2 San 38 7.88 (. °C 4L7 30 –100 30 –200 30 –300 30 –400 30 –500 12. therefore. pitting and crevice corrosion at the water side 4. Bending Composite tubes can be bent by the same methods as those used for single-component tubes. better heat transfer properties. Composite tubes give security based on long experience from low alloyed steels. JIS and other organisations. Temperatures. Composite tubes eliminate risk of SCC. TUBE DIVISION. Stress relieving at 650°C (1200°F) for 30 min. is recommended. low alloyed steel. Composite tubes eliminate low alloyed/high alloyed joints 6. . Ask for our reference list. Joint welding of composite tubes relies on carbon to carbon welds 5.Thermal fatigue test Sandvik Sanicro 38 has higher resistance against thermal fatigue than 3R12 and. and the suitability of a material for a specific application can be confirmed only when we know the actual service conditions. * Swedish patent publication No. Sandvik and Sanicro are trademarks owned by Sandvik AB. ���� ����������� �� ��� ��� ��� ��� ��� ��� Arguments for composite tubes versus normal stainless tubing Environment: outside – flue gas inside – water or steam 1. The mechanical. well tested. For narrower radii. with the added bonus of substantially improved corrosion resistance. Composite tubes have lower thermal expansion 2.595. Cancels June 1996. PHONE +46 26-26 30 00 FAX +46 26-25 27 70 www. 9102410-9. ��� In summary � �� ���� ������� ������� �� ����� ��� Figure 9. 9). Approval to ISO 9001 is also held. SWEDEN. Deliveries of Sandvik Sanicro 38/4L7 • In total > 30 000 metres have been delivered. as well as product approvals from LRQA. after cold bending or welding. of which • > 20 000 metres have been installed in recovery boiler floors • The first installation was made in 1991 • The first complete floor installation was made in 1996. Composite tubes are easier to bend. Composite tubes have higher thermal conductivity. Printed in Sweden. Recommendations are for guidance only. Sandvikens Tryckeri AB Stress relieving of composite tubes. patent pending in other countries.324. hot bending is recommended. Cold bending is recommended for radii down to 2.5 x D. SANDVIK MATERIALS TECHNOLOGY. SE-811 81 SANDVIKEN. COMPOSITE TUBES. holding and quenching times are the same as for carbon steel tubing. Continuous development may necessitate changes in technical data without notice.sandvik. welding and bending properties of a composite tube are based on a conventional. Maximum temperatures where the samples survived 1000 thermal cycles from room temperature. USA patent 5. can be carried out without any loss of strength or corrosion resistance. Heat treatment Sandvik Materials Technology has a quality assurance system approved by internationally recognised bodies and holds an ASME Quality System Certificate as a Materials Organisation.smt. resists larger thermal fluctuations than 3R12 (see fig. see table 3 3.com S-12126-ENG. for Sandvik 38/4L7. Jan 2003.