Home > Welded Pipes > ASTM A312 / A358 / A409
Stainless Steel Large Diameter Welded Pipes (ASTM A312 / A358 / A409) Manufacturer, Supplier & Exporter – Inox Steel India
Inox Steel India is a leading manufacturer, stockist, and global exporter of large diameter stainless steel welded pipes as per ASTM A312, ASTM A358, and ASTM A409. We supply these pipes in 304, 304L, 316, 316L, 321, 347, and 310 grades, engineered for corrosion resistance, high-temperature service, process media transport, and architectural applications.
Our large diameter SS welded pipes are produced using ERW, EFW, and heavy-duty longitudinal welding, followed by solution annealing, pickling, polishing, and 100% NDT to ensure reliability in industrial, structural, and utility piping systems. With strong export capabilities, Inox Steel India caters to major markets in UAE, Saudi Arabia, Qatar, Oman, Bahrain, Kuwait, South Africa, Europe, USA, Mexico, and Australia, supplying both project pipes and custom fabricated sizes.
We offer diameters ranging from 8” to 72”, with both standard and custom wall thicknesses suitable for chemical plants, refineries, water pipelines, HVAC systems, pulp & paper industries, food processing, and large architectural structures.
Large diameter SS welded pipes are manufactured from stainless steel plates or coils by using longitudinal welding processes (ERW / EFW) and are mostly used where:
✔ ASTM A312 – SS Welded Process & Utility Piping
Used for general corrosion service, chemical transfer lines, and industrial process systems.
✔ ASTM A358 – SS EFW Large Bore Pipes
Manufactured using Electric Fusion Welding (EFW) for high-temperature and high-pressure service in power plants, refineries, and petrochemical units.
✔ ASTM A409 – SS Large Diameter Tubing
Used for large OD, thin-to-medium wall polished tubing in architectural, exhaust, ventilation, and low-pressure process systems.
To match your sample style, here is the same detailed breakdown:
1️⃣ Raw Material Selection
Plates or coils in grades 304/304L/316/316L/321/347/310 are checked for chemistry, hardness, and surface quality.
2️⃣ Cutting & Edge Beveling
Plates are cut and bevelled for uniform weld penetration in EFW/ERW processes.
3️⃣ Forming / Rolling
The plate is rolled into a cylindrical shape using heavy-duty forming machines.
4️⃣ Welding (ERW / EFW / Longitudinal Weld)
Depending on the standard:
5️⃣ Heat Treatment (Solution Annealing)
Removes internal stress, stabilizes grain structure, and improves corrosion resistance.
6️⃣ Pickling & Passivation
Enhances corrosion resistance and restores the clean stainless steel surface.
7️⃣ Non-Destructive Testing
Includes:
✔ ERW Large Diameter Pipes (A312)
For general service, water lines, structural use, and atmospheric corrosion applications.
✔ EFW / Heavy Duty Large Diameter Pipes (A358)
For refineries, petrochemical plants, HRSG, high-temperature and corrosive fluid service.
✔ Welded & Annealed Large Diameter Tubing (A409)
For exhaust systems, ventilation ducts, architectural structures, marine applications.
Industrial Applications
High Temperature Applications
Structural & Architectural Applications
| Parameter / Property | ASTM A312 (SS Welded / Large Bore) | ASTM A358 (SS EFW – Large Bore) | ASTM A409 (SS Large Diameter Tubing) |
|---|---|---|---|
| Material Type | Austenitic Stainless Steel | Austenitic Stainless Steel | Austenitic Stainless Steel |
| Purpose | General corrosion service | High-temp & process piping | Large-diameter welded tubes |
| Common Grades | 304 / 304L / 316 / 316L / 321 / 347 | 304 / 304L / 316 / 316L / 310 / 321 / 347 | 304 / 304L / 316 / 316L |
| Diameter Range | 8” – 48” | 16” – 60” | 14” – 72” |
| Wall Thickness | SCH 10 – SCH 80 / Custom | SCH 5 – SCH 160 / Custom | 1.65 mm – 12.7 mm (Tube Standard) |
| Manufacturing Process | ERW / EFW / Welded | EFW (Electric Fusion Welded) | Welded & Annealed |
| Weld Type | ERW / EFW | Full Penetration EFW | Longitudinal Weld |
| Heat Treatment | Solution Annealed | Solution Annealed / Heat Treated | Welded & Annealed |
| Surface Finish | Pickled / Annealed / Polished | Mill Finish / Polished | Bright Annealed / Polished |
| NDT Requirements | Eddy Current / Hydro Test | RT / UT / Hydro | Eddy Current / Hydro |
| Corrosion Resistance | High (depending on grade) | High | High |
| Temperature Suitability | Up to 870°C (316/310 higher) | Up to 1100°C (310/321) | Moderate/High depending on grade |
| Applications | Water, food, pharma, structural | Refineries, chemical plants, HRSG | Exhaust systems, architectural use |
| Standards Compliance | A312 / SA312 | A358 / SA358 | A409 |
| End Types | Plain / Bevelled | Plain / Bevelled | Plain Ends |
| Testing Documents | MTC 3.1, Hydro, NDT | MTC 3.1, RT Films, UT | MTC 3.1, Hydro |
| HSN Code | 7306.40 | 7306.40 | 7306.40 |
A312 – Welded / EFW Large Diameter Pipes
A358 – EFW Heavy Duty Large Bore Pipes (High Temp + Corrosive)
A409 – Large Diameter Welded Tubing
Outside Diameter (OD)
Custom OD available up to 72 inches depending on application (air ducts, architectural piping, process utilities).
Wall Thickness
Length
End Finish
Surface Finish Options
| Element | 304 / 304L | 316 / 316L | 321 / 347 |
|---|---|---|---|
| C | 0.08 max / 0.03 | 0.08 max / 0.03 | 0.08 max |
| Cr | 18–20% | 16–18% | 17–19% |
| Ni | 8–10.5% | 10–14% | 9–12% |
| Mo | — | 2–3% | — |
| Ti (321) | — | — | Stabilized |
| Nb (347) | — | — | Stabilized |
| Property | 304/304L | 316/316L | 321/347 |
|---|---|---|---|
| Tensile Strength | 515 MPa | 515 MPa | 515 MPa |
| Yield Strength | 205 MPa | 205 MPa | 205 MPa |
| Elongation | 35–40% | 35–40% | 35–40% |
| Hardness | 90 HRB | 95 HRB | 95 HRB |
| Temp. Suitability | ~870°C | ~925°C | ~900°C |
| Type | Price (INR/kg) | Price (USD/kg) |
|---|---|---|
| A312 SS Large Diameter | ₹ 350 – ₹ 600 | $ 4.80 – $ 8.50 |
| A358 EFW Large Bore | ₹ 420 – ₹ 720 | $ 5.80 – $ 9.90 |
| A409 Large OD Tubing | ₹ 300 – ₹ 550 | $ 4.10 – $ 7.50 |
| Polished Finish Add-on | +₹ 25 – ₹ 60 | +$ 0.35 – $ 0.80 |
| Custom OD/Heavy Wall | Project-Based | Project-Based |
Prices vary by OD, WT, polish type, grade, welding class & documentation.
✔ Mandatory Tests
✔ A358-Specific Testing
✔ Documentation
7306.40 — Stainless Steel Welded Pipes & Tubes
Middle East:
Africa:
Europe:
Americas:
Asia Pacific:
Industries That Use These Pipes:
Inox Steel India is one of the most reliable manufacturers and exporters of large-diameter stainless steel welded pipes in India, offering consistent quality, prompt delivery, and complete documentation for international projects.
✔ Why Engineers & EPC Companies Trust Us:
We support EPC contractors, shutdown maintenance teams, OEMs, and large industrial plants with custom OD, WT, lengths, coatings, and finishes.
✔ Industrial Applications
✔ High-Temperature Applications
✔ Food & Pharmaceutical Applications
✔ Structural & Architectural Applications
Large diameter SS pipes combine corrosion resistance, aesthetics, durability, and structural load-bearing capability, making them ideal for both industrial and architectural use.
To match your sample style, here is the precise layout:
✔ Standard Packing
✔ Polished Pipe Packing
✔ Container & Export Packing
✔ Ports of Dispatch
JNPT • Mundra • Hazira • Chennai • Vizag
Looking for Stainless Steel Large Diameter Welded Pipes (A312 / A358 / A409) for your project?
52-A, Mulji Thackersi Bldg, Islampura Street, Shop No. 10, Near Alankar Cinema, Mumbai – 400 004
steel@inoxsteelindia.in
+91 9930796690
Yes — especially grades 316, 321, 347, and 310, widely used in HRSG, furnaces, hot air ducts and exhaust systems.
Yes — No.4 & No.8 mirror finish is available for architectural/structural use.
Up to 72 inches (1.8 meters), depending on standard and application.
Yes — TPI agencies: SGS, BV, DNV, TÜV, Lloyd’s Register.
We deliver certified, tested, and export-quality large diameter SS welded pipes worldwide.