We are Riddhi Siddhi Impex, a Mumbai-based supplier and stockist of Stainless Steel 309 Coils, established in 2002. We stock SS 309 coils to ASTM A240 / ASME SA-240 in 0.03 mm to 5 mm thickness and widths from 3 mm to 2000 mm, hot rolled and cold rolled. As an ISO 9001, 14001, and 45001 certified company, we supply every order with EN 10204 Type 3.1 / 3.2 mill test certificates on request.
Stainless Steel 309 coils are heat-resistant austenitic stainless steel products containing 22-24% chromium and 12-15% nickel, supplied in coil form for fabrication into high-temperature components. It is between 304 and 310S: more scale resistance than 304, lower alloy cost than 310S. The steel resists oxidation up to 1095 °C in continuous service and around 980 °C under intermittent heating, since thermal cycling spalls the protective scale. Modern A240 flat products are certified as 309S, which caps carbon at 0.08% and keeps weld zones free of carbide precipitation. Density is 8.0 g/cm³, and this coil is widely applied in power generation and furnace components.
As a reliable 309 Stainless Steel Coil supplier and stockist, the Stainless Steel coils are sourced from reputed primary mills, with a width between 3 mm and 2000 mm at ±0.1 mm. Material ships annealed to ASTM A240, with coil ID from 150 mm to 610 mm.
We provide ASTM A240 Grade 309 coils in annealed, hot rolled, and cold rolled, covering the finishes, edge options, and dimensional ranges listed in the table below.
| Parameter | Details |
|---|---|
| Standard | ASTM A240 / ASME SA-240 |
| Thickness | 0.03 mm to 5 mm |
| Width | 3 mm to 2000 mm |
| Width Tolerance | ±0.1 mm |
| Coil ID | 150 mm to 610 mm |
| Coil OD | Up to 1800 mm |
| Condition | Annealed (Soft) |
| Supply Forms | Hot rolled, Cold rolled |
| Surface Finish | 2B, BA, Matte, Matte PVC, Scotch-Brite |
| Edge | Slit edge, Mill edge, Deburred edge, Round edge |
Chromium does the heavy lifting here, forming the oxide scale that shields the steel at extreme heat, while nickel holds the structure austenitic and ductile. Values follow ASTM A240 for UNS S30908.
| Element | Composition (%) |
|---|---|
| Carbon (C) | 0.20 max |
| Manganese (Mn) | 2.00 max |
| Phosphorus (P) | 0.045 max |
| Sulphur (S) | 0.030 max |
| Silicon (Si) | 0.75 max |
| Chromium (Cr) | 22.0-24.0 |
| Nickel (Ni) | 12.0-15.0 |
| Nitrogen (N) | 0.10 max |
| Iron (Fe) | Balance |
Tensile strength defines the working margin. Annealed ASME SA-240 Grade 309 coil delivers 515 MPa minimum with 40% elongation, so it draws, bends, and rolls without cracking. No hardness ladder applies to this grade.
| Property | Value |
|---|---|
|
Tensile Strength, minimum
|
515 MPa (75 ksi) |
|
Yield Strength (0.2% offset), minimum
|
205 MPa (30 ksi) |
|
Elongation in 50 mm, minimum
|
40% |
|
Hardness, maximum
|
217 HBW / 95 HRB |
Buyers who specify by AISI 309, SUS 309, or a national standard can cross-check the designations below. Each row points to the same 23Cr-13Ni heat-resistant austenitic steel.
| Country / Standard | Designation |
|---|---|
| USA (UNS) | S30900 |
| Europe (EN) | X12CrNi23-13 |
| Germany (W.Nr) | 1.4833 |
| Japan (JIS) | SUS309 |
| China (GB) | 06Cr23Ni13 |
| Russia (GOST) | 20Х23Н13 |
These 4 industries use most of the Alloy 309 coils we dispatch. Each one picks the grade for sustained heat exposure, where 304 scales away and 310S costs more than the duty demands.
Furnace fabricators form 309 stainless steel coil into muffles, radiant tube shields, annealing covers, and charge baskets. The grade keeps its section through years of firing cycles. Where a 304 component thins and flakes within months at 900 °C, Type 309 stainless steel holds a tight, adherent scale.
Refineries and chemical plants specify SS 309 coils for thermowells, heater sleeves, and heat exchangers handling hot process gas. Sulphur-bearing atmospheres need supervision above 980 °C, yet in oxidising service the grade runs reliably. Its nickel content also blunts carburisation in cracking units.
Boiler makers cut baffles, burner surrounds, and superheater supports from Alloy 309 coils because the steel keeps yield strength at flue-gas temperatures. Coal and biomass stations value their resistance to corrosive ash. Repeated shutdowns test the scale, and 309 tolerates that cycling to roughly 980 °C.
Kiln builders line preheater sections, cooler plates, and drying tunnels with 309 stainless steel coil. Abrasive dust combines with heat in these plants, a pairing that strips leaner grades quickly. The 23% chromium content maintains a tough oxide layer that resists both forms of damage at once.
Orders leave from our Mumbai and Taloja warehouses packed for sea freight, marked according to instructions.
| Parameter | Details |
|---|---|
| Packaging | Wooden cases, pallet packing |
| Incoterms | FOB, CIF, CFR, EXW Mumbai |
| Dispatch Points | Mumbai and Taloja warehouses |
| Standard Lead Time | 4 to 5 days |
| Urgent Dispatch | 2 to 3 days |
| Payment Terms | Advance, credit, LC |
| Certification | EN 10204 Type 3.1 / 3.2 on request |
Stainless Steel 309 coils price in India ranges between ₹650-₹1,000 per kg, about $3.26-$4.85 per kg for export buyers. Nickel and chromium market rates move the figure, and thickness, width, finish, and quantity settle the final quote. WhatsApp or call us for today's rate.
The difference between 309 and 309S is carbon. Plain 309 permits 0.20% maximum, while 309S limits it to 0.08%, and ASTM A240 certifies flat-rolled coil to the 309S composition, which protects welds from intergranular attack.
SS 309 coils outlast SS 304 coils above roughly 870 °C, the point where 304 scales heavily. The extra chromium keeps 309 serving continuously to 1095 °C in oxidising atmospheres.
309 stainless steel coils withstand 1095 °C in continuous service and about 980 °C where heating is intermittent, since expansion and contraction crack the oxide scale under cycling.
We keep SS 309 coils from 0.03 mm to 5 mm thick and slit any width from 3 mm to 2000 mm at ±0.1 mm tolerance. Coil ID spans 150 mm to 610 mm; OD reaches 1800 mm.
Yes, every consignment of 309 stainless coils can carry an EN 10204 Type 3.1 or 3.2 certificate, together with a technical data sheet on request.
You can source Stainless Steel 309 Coils in India from us at Riddhi Siddhi Impex. Ready stock is kept in our Mumbai and Taloja warehouses, and get a quote within 24 hours by phone or WhatsApp.
