SS 317 / 317L
SS 317/317L: Specifications | Grades & Standards | Product Types | Equivalent | Chemical | Mechanical | BW Fittings | Forged Fittings | Flanges | FAQ
Leading Manufacturers & Exporters of ASTM A403 Stainless Steel 317 Pipe Fittings and ASTM A182 SS 317L Forged Fittings & Flanges, including Elbows, Tees, Reducers, Stub Ends, and Crosses. We supply UNS S31700 / S31703 Fittings and EN 1.4449 / 1.4438 SORF, WNRF Flanges – delivering High-Performance, Acid-Resistant Piping Solutions to industries worldwide.
Best Export Prices: sales@midlandforgefittings.com
Midland Forge and Fittings Pvt. Ltd. is a premier manufacturer and exporter of high-quality stainless steel 317/317l pipe fittings and flanges. With a strong commitment to precision engineering and international standards, we specialize in ASTM A182, A403, and equivalent certified forged and buttweld fittings, including elbows, tees, reducers, stub ends, crosses, and flanges. Our products are designed to withstand extreme temperatures, high pressures, and corrosive environments.
Quality and reliability are at the core of everything we do. Our global clientele trusts us for durable, corrosion-resistant, and precision-engineered fittings and flanges, backed by timely delivery and excellent customer support. From standard sizes to customized solutions, we are dedicated to meeting diverse industrial requirements and providing high-performance piping systems that drive operational efficiency and reliability.
Stainless Steel 317 is a highly corrosion-resistant austenitic stainless steel containing higher levels of molybdenum (Mo) and chromium (Cr) compared to SS 316, providing superior resistance to oxidation, pitting, and crevice corrosion in chloride-rich and acidic environments. It exhibits excellent tensile strength, toughness, and ductility at both ambient and elevated temperatures, making it suitable for chemical processing, petrochemical, and high-temperature industrial applications. SS 317 buttweld and forged fittings, including elbows, tees, reducers, stub ends, and flanges, are manufactured to ASTM A403 and A182 standards, ensuring precise dimensional tolerances, smooth weldability, and compatibility with UNS S31700 piping systems.
Stainless Steel 317L is the low-carbon variant of SS 317, designed to minimize sensitization and intergranular corrosion during welding operations. With excellent corrosion resistance, high-temperature strength, and formability, it is ideal for applications requiring welded joints and heavy-duty chemical service. SS 317L fittings and flanges, including tees, elbows, reducers, crosses, and flanges, are manufactured in compliance with ASTM A403, A182, and EN 1.4438 standards, ensuring durable, acid-resistant, and dimensionally accurate components. These fittings are widely used in chemical, pharmaceutical, and offshore industries where long-term performance under aggressive media is critical.
Stainless Steel 317 Buttweld Fittings - Specifications
SS 317L Socket weld Fittings – Grades & Standards
| Grade | Buttweld Fittings Standards | Forged Fittings Standards | Flanges Standards |
|---|---|---|---|
| 317 | ASTM A403 / ASME B16.9 / MSS-SP-43 | ASTM A182 / ASME B16.11 | ASTM A182 / ASME B16.5 / B16.47 |
| 317L | ASTM A403 / ASME B16.9 / MSS-SP-43 | ASTM A182 / ASME B16.11 | ASTM A182 / ASME B16.5 / B16.47 |
SS 317/317L – Industrial Flanges, Fittings & Piping Products
ASTM A182 SS 317 Forged Fittings - Equivalent Grades
| Grade | UNS | ASTM | EN (DIN) | JIS | GOST | BS | AFNOR |
|---|---|---|---|---|---|---|---|
| 317 | S31700 | A240 / A276 | 1.4436 (X7CrNiMo17-12-2) | SUS317 | 08Х17Н12М3 (08X17H12M3) | 317S31 | Z6CN17-12-02 |
| 317L | S31703 | A240 / A276 | 1.4438 (X2CrNiMo17-12-3) | SUS317L | 08Х17Н12М3Л (08X17H12M3L) | 317S11 | Z2CN17-12 |
ASTM A403 SS 317 Buttweld Pipe Fittings - Chemical Composition
| Grade | C (%) | Mn (%) | Si (%) | Cr (%) | Ni (%) | Mo (%) | P (%) | S (%) | N (%) |
|---|---|---|---|---|---|---|---|---|---|
| 317 | 0.04 – 0.08 | 2.0 | 1.0 | 18 – 20 | 11 – 15 | 3 – 4 | 0.045 max | 0.03 max | 0.11 max |
| 317L | ≤ 0.03 | 2.0 | 1.0 | 18 – 20 | 11 – 15 | 3 – 4 | 0.045 max | 0.03 max | 0.11 max |
SS 317L Flanges - Mechanical Properties
| Grade | Tensile Strength (MPa) | Yield Strength (MPa) | Elongation (%) | Hardness (HB) | Hardness (HRB) | Hardness (HRC) |
|---|---|---|---|---|---|---|
| 317 | 515 – 750 | 205 min | 40 min | ≤ 201 | ≤ 92 | ≤ 25 |
| 317L | 515 – 700 | 170 min | 40 min | ≤ 190 | ≤ 90 | ≤ 25 |
317/317L SS Buttweld Fittings – Seamless, Welded & Fabricated Types
Different Types of SS 317 / 317L Flanges Used in Industrial Piping
Stainless Steel 317/317L Forged Fittings – Complete Guide
What is Stainless Steel 317 and 317L, and how do they differ?
SS 317:
High-alloy austenitic stainless steel with higher molybdenum (3–4%) and chromium (18–20%) content than SS 316.
Offers superior resistance to pitting, crevice corrosion, and aggressive acids, particularly in chloride environments.
Suitable for high-temperature and high-pressure piping systems, including chemical and petrochemical applications.
SS 317L:
Low-carbon variant (≤0.03%) of SS 317, designed to minimize carbide precipitation during welding.
Reduces the risk of intergranular corrosion in welded joints.
Preferred for heavily welded structures and long-term corrosive service, while maintaining almost the same corrosion resistance as 317.
What are the welding and fabrication considerations for SS 317L?
Preheat the material to 150–200°C before welding for stress relief.
Use low-carbon or matching filler metals (e.g., ER317L) to prevent intergranular corrosion.
Avoid prolonged exposure in the 450–850°C range, which can cause sensitization.
Post-weld heat treatment is optional but recommended for critical chemical service pipelines.
Suitable for TIG, MIG, and arc welding processes.
Why choose 317L over 317 for welded piping systems?
Lower carbon content prevents sensitization and intergranular corrosion in the heat-affected zone.
Ensures long-term corrosion resistance in welded joints.
Better for complex piping networks with multiple welds.
Slightly lower yield strength is acceptable for applications prioritizing corrosion resistance over mechanical strength.