Stainless Steel Welded Pipes
Giriraj Impex stocks, supplies and exports stainless steel welded pipes to ASTM A312, A358 and A778 in grades 304, 304L, 316, 316L, 321 and 310S. We supply stainless steel welded pipes from approved mills, made by electric resistance welding (ERW) or electric fusion welding (EFW), in nominal sizes from small bore up to large diameters, in schedules 5S, 10S, 40S and 80S and heavier walls on request.
Welded stainless pipe gives the corrosion resistance of the grade at a lower cost than seamless pipe and in sizes where seamless is not practical. It is widely used for water, utility, chemical, food and pharmaceutical lines and for large-diameter process and seawater headers.
Which welded pipe standard?
| Standard | What it covers | Typical use |
|---|---|---|
| ASTM A312 (welded) | Welded austenitic stainless pipe made without filler metal, heat treated | General process piping in small and medium sizes |
| ASTM A358 | Electric fusion welded austenitic pipe for high-temperature service, made from plate, with classes that set filler metal and radiography | Large-diameter and heavy-wall process lines |
| ASTM A778 | Welded, unannealed austenitic stainless tubular products | Low-temperature, low-pressure corrosive service such as pulp and paper and water |
| ASTM A928 | EFW duplex stainless pipe | See duplex pipes |
Specifications
| Item | Details |
|---|---|
| Welding process | ERW, EFW (TIG, plasma or laser), with or without filler metal |
| Dimensional standard | ASME B36.19M; ASME B36.10M for heavier walls and large sizes |
| Schedules | 5S, 10S, 40S, 80S; other walls to order |
| Grades | 304, 304L, 316, 316L, 321, 310S; dual certified 304/304L and 316/316L |
| Weld treatment | Weld bead removed or rolled; solution annealed as the standard requires |
| Finish | Annealed and pickled; polished on request |
| Ends | Plain or bevelled to ASME B16.25 |
| Documents | Mill test certificate (MTC); radiography and third-party inspection on request |
Grades and properties
Welded pipe to ASTM A312 has the same chemical and tensile requirements as seamless pipe of the same grade; the standard adds weld-specific tests. Grade pages: SS 304 pipes and SS 316 pipes.
| Grade | UNS | C | Mn | P | S | Si | Cr | Ni | Mo |
|---|---|---|---|---|---|---|---|---|---|
| TP304 | S30400 | 0.08 | 2.00 | 0.045 | 0.030 | 1.00 | 18.0–20.0 | 8.0–11.0 | – |
| TP304L | S30403 | 0.035 | 2.00 | 0.045 | 0.030 | 1.00 | 18.0–20.0 | 8.0–13.0 | – |
| TP316 | S31600 | 0.08 | 2.00 | 0.045 | 0.030 | 1.00 | 16.0–18.0 | 10.0–14.0 | 2.00–3.00 |
| TP316L | S31603 | 0.035 | 2.00 | 0.045 | 0.030 | 1.00 | 16.0–18.0 | 10.0–14.0 | 2.00–3.00 |
Other elements and footnotes as given in the standard. Dual-certified material meets both grades.
| Grade | Tensile strength, MPa (ksi) | Yield strength, MPa (ksi) | Elongation in 50 mm, % (longitudinal) |
|---|---|---|---|
| TP304 | 515 (75) | 205 (30) | 35 |
| TP304L | 485 (70) | 170 (25) | 35 |
| TP316 | 515 (75) | 205 (30) | 35 |
| TP316L | 485 (70) | 170 (25) | 35 |
Transverse elongation and other requirements as given in the standard.
How the weld is checked
Each length of A312 welded pipe receives a hydrostatic or non-destructive electric test, and samples are flattened and bent to prove the weld. Under ASTM A358, the class ordered decides whether the longitudinal weld is fully radiographed and whether filler metal is used, so the class must be stated on the order. Pipes are marked with specification, grade, size, schedule, heat number and "WLD" to show the welded construction. We check each delivery against the mill test certificate and purchase order before dispatch.
Applications
Stainless steel welded pipes are used for process water and effluent lines, cooling water and desalination, pulp and paper, chemical transfer lines, dairy, brewery and food processing, pharmaceutical utilities, firewater and seawater systems, and architectural and structural work. When a seamless product is required, see stainless steel seamless pipes; for heat-exchanger and instrument duties see stainless steel tubes. All welded products are on the welded pipes and tubes page and the full material range on the stainless steel page.
Thin-wall welded pipe in schedules 5S and 10S keeps weight and cost down in low-pressure systems, while the same nominal sizes in schedule 40S suit higher pressures.
Large-diameter EFW pipe is often fabricated with matching welded fittings for headers and ducts.
Ordering welded stainless pipe
For hygienic duties, welded stainless pipe and tube can be supplied with polished bores and outside surfaces to a stated roughness; for architectural use, with a polished external finish. Please include in your enquiry:
- standard and grade, with the class for ASTM A358;
- size and schedule or wall thickness;
- surface finish inside and outside;
- length and end preparation;
- radiography, hydrostatic or other extra tests;
- quantity, inspection and delivery location.
Matching components
Welded pipe lines are completed with butt-weld stainless steel pipe fittings, flanges and stud bolts and nuts in the same grade. For tanks, supports and fabricated parts we also supply stainless plates, sheets, coils, circles, rings, round bars, wires, angles, channels and flats.
Frequently Asked Questions
ERW pipe is joined by heating the strip edges with electric current and pressing them together without filler. EFW pipe is joined by fusion with an arc, with or without filler metal, and is used for larger diameters and heavier walls, for example to ASTM A358.
Under ASTM A312 the chemical and tensile requirements are the same for welded and seamless pipe of a grade. The difference is the longitudinal weld, which is heat treated and tested as the standard requires.
The class number in ASTM A358 sets how the pipe is welded and examined – for example whether filler metal is used and whether the weld is fully radiographed. It must be stated on the order.
ASTM A778 covers welded, unannealed stainless steel pipe for low-temperature, low-pressure corrosive service, such as pulp and paper mills and water treatment, where solution annealing is not required.
Yes. Weld radiography can be specified, and is built into some ASTM A358 classes. Please state the radiography requirement and acceptance standard with your enquiry.
Welded pipe is supplied in 304, 304L, 316, 316L, 321 and 310S, and as dual certified 304/304L and 316/316L. Duplex welded pipe is supplied to ASTM A790 and A928.
Request a Quote for Stainless Steel Welded Pipes
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