Pipe grades fail quietly and get replaced loudly, which is why the grade call matters more than the price call. Metinox Overseas is a stainless steel pipes manufacturer and supplier in Mumbai, stocking 304, 316L, 310S, 321 and duplex in seamless, welded and EFW form to ASTM A312, A358 and A790, and exporting to project sites across India, the USA, the Middle East and Africa. Every heat is 3.1 certified and mill traceable. Nothing on this page is exotic; all of it is the material refineries, food plants and water utilities actually run on. The full catalogue sits under Pipes & Tubes; this page is the pipe half of it.
Two links settle most enquiries straight away. General service in fresh or treated water: SS 304 Pipes carries the default grade end to end, weight charts and tolerances included. Chlorides, acids or coastal air: SS 316/316L Pipe is the page to open. The folds below exist for everyone still deciding.
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Table of Contents
Types of Stainless Steel Pipes Products
Stainless Steel 304 Pipes
Stainless Steel 304L Pipes
Stainless Steel 304H Pipes
Stainless Steel 310S Pipes
Stainless Steel 310H Pipes
Stainless Steel 316/316L Pipes
Stainless Steel 316H Pipes
 316Ti Welded Pipes.webp)
Stainless Steel 316Ti Pipes
Stainless Steel 317/317L Pipes
Stainless Steel 321/321H Pipes
Stainless Steel 347/347H Pipes
Stainless Steel 904L Pipes
Stainless Steel Pipe Grades: Which One Does Your Line Need?
Seven grades cover almost every pipe enquiry we see. Each row links to a full page with chemistry, properties, sizes and tolerances for that grade.
| Grade | UNS | Pick it for |
|---|---|---|
| SS 304 Pipes | S30400 | The default: water, food, utilities and general process below the chloride and temperature limits |
| SS 304L Pipe | S30403 | Lines welded in place and left as-welded; the low carbon protects the weld zone |
| SS 304H Pipe | S30409 | Sustained strength above roughly 500°C, where creep governs the design |
| SS 316/316L Pipe | S31600 / S31603 | Chlorides, acids, coastal atmospheres; the molybdenum earns its premium |
| SS 310S Pipe | S31008 | Furnace, flue and heat-treatment duty, scaling resistance to about 1100°C |
| SS 321/321H Pipe | S32100 / S32109 | Thermal cycling through the 425 to 860°C band; titanium stabilization holds the grain boundaries |
| Duplex Steel Pipes | S31803 / S32205 | High-strength chloride duty; near immunity to the cracking that limits the austenitics |
Grades 904L, 347/347H and super duplex are supplied against order for acid, high-temperature-stabilized and seawater duties; name the service and we will quote the grade.
Grade First, Then Route: Seamless, Welded & EFW SS Pipe
Route is the second decision on every order, and it is mostly economics. Seamless costs more per meter and earns it on pressure and critical lines; welded covers general service at a real saving; EFW takes over at large diameters. Our Stainless Steel Seamless Pipes and Stainless Steel Welded Pipes pages cover each route across all grades, our guide on seamless vs welded stainless steel pipe gives the plain-language answer, and the full three-route comparison table with A999 tolerances lives on the SS 304 Pipes page, kept in one place so it stays current.
Reading the Temperature Ladder in SS Piping
Walk it bottom to top. Cryogenic duty down to -196°C belongs to the austenitics, code-accepted at low temperature without impact testing. Ambient to about 400°C, almost any grade on this page works and the fluid decides. The 425 to 860°C band is the trap: standard austenitics held there sensitize at the grain boundaries, so cyclic service takes 321 with its titanium stabilization, and sustained strength duty takes 304H. Above 800°C, furnace and flue work moves to 310S, which is built for scale, not for pressure. And duplex never climbs this ladder at all; its world ends near 300°C. Pin your line's operating and upset temperatures on this ladder and the grade shortlist writes itself.
Where SS Pipe Grades Stop Working
Every grade on this page has a cliff edge. Knowing where they are is cheaper than finding them in service.
- 304 stops at chlorides: pitting in coastal air, and stress corrosion cracking in chloride-bearing media above about 60°C. The step up is SS 316/316L Pipe.
- 316L stops at seawater: brackish and marine duty overwhelm even the molybdenum. That water belongs to Duplex Steel Pipes and super duplex beyond it.
- All standard austenitics stop in the 425–860°C band: held there, they sensitize. Specify 321 for cycling, an L grade for welded excursions, or the H grade for sustained strength.
- Duplex stops near 300°C: above it the structure embrittles, and no procurement discount changes that.
- And one field caution: wet, chloride-leaching insulation on hot stainless lines starts more cracking than the process fluid does. Specify insulation to ASTM C795 and keep it dry.
The 304-versus-316 decision, the one buyers face most often, is argued out properly in our guide SS 304 vs SS 316.
SS Pipe Testing, Certification & Export to USA, Middle East & Africa
The regime does not change with the grade. Pipes are hydrostatically tested or NDE examined per A312 or A790 as applicable, with intergranular corrosion testing to ASTM A262 and PMI verification on request, and dimensions held to ASME B36.19M. An EN 10204 3.1 mill test certificate ships with every order; 3.2 witnessed certification through BV, SGS or TUV is arranged at order stage. Metinox Overseas is an ISO 9001 and PED certified company, approved to the procurement standards of SABIC, ADNOC, KNPC, EIL, IOCL and BPCL, which is why Gulf project paperwork clears without a second round; the program is on our Quality Policy page. Exports move in regular consolidations from Mumbai to the USA, the Middle East and Africa, bundled, end-protected and crated as described on Packing and Dispatch. Ex-stock sizes dispatch in 7 to 14 working days. Made-to-order sizes take 4 to 6 weeks.
Explore the Stainless Steel Pipe Range
- SS 304 Pipes – the default grade, with weight charts, tolerances and the route comparison
- SS 304L Pipe – low carbon for as-welded lines
- SS 304H Pipe – high carbon for sustained strength at temperature
- SS 316/316L Pipe – the chloride answer for chemical and coastal work
- SS 310S Pipe – furnace and flue duty to about 1100°C
- SS 321/321H Pipe – stabilized for thermal cycling
- Duplex Steel Pipes – strength plus chloride cracking resistance
- Stainless Steel Seamless Pipes – the seamless route across all grades
- Stainless Steel Welded Pipes – the welded route across all grades
- Stainless Steel Tubes – the sister category, if your job is OD-and-wall tube rather than pipe
Stainless Steel Pipes: Frequently Asked Questions
Answer two questions and the field narrows fast: how hot does the line run, and what is in the fluid? Ambient to 400 degrees C in clean water points to 304. Chlorides or acids point to 316L. The 425 to 860 degree band points to 321 or an L grade, sustained heat above 800 degrees points to 310S, and high-strength chloride duty points to duplex. Send both answers with the enquiry and the grade names itself.
Yes, from Mumbai on regular consolidations. Gulf supply runs on approvals to SABIC, ADNOC and KNPC procurement standards, US-bound orders carry complete EN 10204 3.1 documentation for import compliance, and African project cargo ships crated with end protection for long transit and rough handling.
A312 covers seamless and straight-seam welded austenitic pipe and is the ordering standard for most stainless process lines. A358 covers electric fusion welded austenitic pipe for pressure service in larger diameters, radiographed by class. A790 is the duplex counterpart of A312, written for grades like 2205 and super duplex.
Half inch to 24 inch NB across the range: seamless to 16 inch, welded to 24 inch, and EFW from 6 to 48 inch against order, in schedules 5S, 10S, 40S and 80S per ASME B36.19M. Heavier walls and cut lengths come on request, and grade availability by size is confirmed in one reply.
No. The chromium oxide film is the coating, and it repairs itself when scratched, which is the whole point of the material. The one field caution is insulation: wet, chloride-leaching insulation on hot stainless lines is a known starter for stress corrosion cracking, so specify insulation compatible with austenitic stainless per ASTM C795 and keep it dry.
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