We are Riddhi Siddhi Impex, an ISO 9001, ISO 14001, and ISO 45001-certified Mumbai-based super duplex steel sheets and plates supplier and stockist established in 2002. We stock hot-rolled plates and cold-rolled sheets to ASTM A240 / ASME SA-240 from reputed primary mills, in widths up to 2000 mm. Ready solution-annealed inventory, a monthly supplying capacity of 400 to 500 tonnes, and dispatch within 4 to 5 days keep corrosion-critical fabrication on schedule.
Super duplex steel sheets and plates are flat-rolled stainless products with a microstructure balanced near half austenite and half ferrite. Each phase earns its keep: ferrite supplies strength, austenite holds toughness and weldability. Chromium near 25%, molybdenum at 3 to 5%, and a deliberate nitrogen addition lift the pitting resistance equivalent number (PREN) beyond 40, the threshold that separates super duplex from standard duplex grades such as 2205. Material above that line resists pitting, crevice attack, and chloride stress corrosion cracking in hot brines that attack 316L. Sheets and plates are divided by gauge and rolling route. Sheets are the thinner cold-rolled product, while plates come off the hot mill for pressure and structural work. One boundary applies: continuous service stays below about 300 °C, because alpha-prime embrittlement, the 475 °C mechanism distinct from sigma phase, slowly reduces toughness above it.
Our Mumbai and Taloja warehouses hold both grades in the solution annealed condition. Cold-rolled sheets run from 3.8 mm to 6 mm. Hot-rolled plates start at 6 mm, and heavier gauges are arranged against order from the same primary mills. Widths cover the standard 1000 mm, 1219 mm, 1500 mm, and 2000 mm sizes, with lengths up to 6000 mm. Chequered plates and perforated sheets follow on confirmed requirement. Every consignment traces back to its mill heat, and technical data sheets accompany the material on request.
We stock 2 super duplex grades in sheet and plate form, both solution annealed with full mill documentation.
S32750 super duplex offers 25Cr-7Ni-4Mo chemistry and 800 MPa strength, enabling thinner plates for offshore, desalination, and chemical equipment.
View gradeS32760 adds tungsten and copper for stronger seawater corrosion resistance, 750 MPa strength, and serves subsea, FGD ducting, and piping.
View gradeWe dispatch super duplex sheets and plates in 3 standard surface finishes, and a single supply condition applies across the range.
HR
Hot rolled plates carry the No.1 pickled surface, descaled to a dull matte face. Process vessels and structural work specify it as standard.
2B
Cold rolling followed by annealing and pickling produces the smooth, semi-reflective 2B surface. Most of our super duplex sheet stock ships this way.
BA
Bright annealing under a protective atmosphere leaves the sheet reflective and oxide free; it doesn't need polishing before fabrication.
HR
Every sheet and plate leaves solution annealed and quenched, which restores the balanced austenite-ferrite structure after rolling. No temper ladder applies to this product form.
3 industrial sectors use most of the super duplex plates and sheets leaving our warehouses. Chloride load and operating temperature at each site determine the grade.
Topside separators, produced-water vessels, and manifold cladding are cut from Super Duplex S32750 plates, whose 800 MPa tensile strength carries pressure at reduced wall thickness. Hardware sitting in permanent seawater below the waterline frequently steps up to S32760.
Reactor shells, columns, and heat exchanger channels in S32750 plate keep a corrosion allowance, whereas 2205 has nothing left. Hot chloride liquors and mixed acid streams control the choice. Where copper improves acid-side performance, buyers move to Super Duplex S32760 sheets for scrubber internals.
Reverse osmosis housings and flash chamber walls run warm brine around the clock, and S32750 sheet survives the duty for years without pitting. Intake screens and evaporator sections in high-velocity seawater are a recurring S32760 order.
Paperwork travels with every plate and sheet consignment. Riddhi Siddhi Impex holds three ISO certifications on top of mill-level traceability.
Each dispatch includes an EN 10204 Type 3.1 mill test certificate traceable to the mill heat. Type 3.2 with a third-party witness is available on request.
Our ISO 9001:2015 certification covers the quality management system behind sourcing, inspection, and supply. Incoming material is checked against order specifications before it reaches stock.
Environmental management runs under ISO 14001:2015, from warehouse storage through packing and dispatch.
ISO 45001:2018 handles occupational health and safety across our warehouse operations.
Flat-rolled stainless products 600 mm or wider fall under HS heading 7219, which covers nearly every sheet and plate we dispatch. Trimmed widths below 600 mm move under 7220. Your customs broker should confirm the final subheading.
Riddhi Siddhi Impex has stocked super duplex flat products in Mumbai since 2002, supplying buyers across India and abroad. Call or WhatsApp our team and get a quote within 24 hours.
