We are Riddhi Siddhi Impex, an ISO 9001, ISO 14001, and ISO 45001-certified Mumbai-based super duplex steel coils supplier and stockist established in 2002. We stock hot rolled and cold rolled coils to ASTM A240 / ASME SA-240 from reputed primary mills and slit them in-house to any width between 3 mm and 2000 mm. Ready solution-annealed inventory, a monthly supply capacity of 400 to 500 tonnes, and dispatch within 4 to 5 days keep corrosion-critical projects on schedule.
Super duplex steel coils are continuous flat-rolled lengths of duplex stainless steel wound after hot or cold rolling, with a microstructure balanced at roughly half austenite and half ferrite. The two phases split the work between them. Ferrite carries strength, while austenite preserves toughness and weldability. Chromium near 25%, molybdenum between 3 and 5%, and a deliberate nitrogen addition lift the pitting resistance equivalent number past 40. PREN is worked out as %Cr + 3.3(%Mo + 0.5%W) + 16%N, and a result above 40 is what separates super duplex from standard duplex grades. Coils in this family resist pitting, crevice attack, and chloride stress corrosion cracking in hot seawater and brine that would corrode 316L, with yield strength roughly double that of common austenitic coil. One service boundary applies: keep continuous operating temperature below about 300 °C, because alpha-prime embrittlement (the 475 °C mechanism) slowly drains toughness above that point.
Our warehouses in Mumbai and Taloja hold super duplex steel coil stock ready for dispatch or slitting. Hot rolled coils run from about 2 mm to 5 mm thick; cold rolled coils start at 0.03 mm. Every source coil arrives with its mill documentation before anything is slit, so heat numbers stay traceable from the melt right through to the delivered width. Buyers order full parent coils or slit widths from the same inventory, and technical data sheets travel with the material on request. Wooden case or pallet packing protects the coil surface during sea freight.
We hold a ready stock of 2 super duplex coil grades, UNS S32750 and UNS S32760. Both are supplied solution annealed to ASTM A240. The two chemistries overlap in strength yet diverge in crevice performance, so most enquiries settle on one of them quickly.
S32750 (25Cr-7Ni-4Mo, EN 1.4410) dominates orders, offers PREN ≥41 and 795 MPa strength, enabling thinner, always-stocked coils.
View gradeS32760 (EN 1.4501) serves crevice-critical subsea and FGD duty; W and Cu boost resistance while ASTM A240 preserves formability.
View gradeWe supply super duplex steel coils in 2 finishes. The rolling route decides which of them applies at a given thickness.
2B
Annealing and pickling, followed by a light final pass, produce the smooth, semi-reflective 2B face. Most cold-rolled SDSS coils leave our warehouse in this condition.
BA
A protective-atmosphere anneal preserves a reflective, oxide-free surface. Parts made from BA coil don't need further polishing before service.
Most super duplex stainless steel coils dispatched from our warehouses serve 3 industrial sectors. Chloride concentration and operating temperature decide the grade for each order.
Produced water systems, seawater lift circuits, and topside heat exchangers draw on Super Duplex S32750 Coils for combined strength and pitting resistance. Where cathodic protection or tight crevice geometry enters the picture, engineers move to S32760. Platform fabricators also convert slit coil into clamps, banding, and instrumentation parts for the same environments.
Reactor cladding, scrubber internals, and heat exchanger components face hot chlorides and mixed acid streams daily. Super Duplex S32760 Coils take the harshest of these exposures, while S32750 covers the bulk of chloride-bearing process duty. We keep both grades in stock so plants can swap out corroded austenitic components within a shutdown window.
Reverse osmosis plants circulate warm, high-chloride brine around the clock. Fabricators form Super Duplex S32750 Coils into brine headers, membrane housing components, and pump internals that survive this duty for years without pitting. Evaporator ducting in thermal desalination lines follows the same grade choice.
Documentation follows every coil from mill heat to dispatch. Riddhi Siddhi Impex operates under three ISO certifications alongside mill-level traceability.
Every coil carries an EN 10204 Type 3.1 mill test certificate traceable to the mill heat. Type 3.2 certification is arranged on request.
Our ISO 9001:2015 certification controls quality management across stocking, slitting, and supply operations.
Environmental management runs under ISO 14001:2015, covering coil storage, material movement, and waste handling.
ISO 45001:2018 covers occupational health and safety across our warehouse and slitting lines.
Flat-rolled super duplex coils fall under HS heading 7219 when 600 mm or wider and 7220 below that width. Full-width source coils and any slit coil 600 mm or wider ship under 7219; only slit widths below 600 mm move under 7220. Confirm the final subheading with your customs broker before export.
Yes. We slit any width between 3 mm and 2000 mm, holding tolerance to ±0.1 mm. Coil ID runs from 150 mm to 610 mm, with OD up to 1800 mm, and slit, deburred, or round edges are finished to your specification.
Riddhi Siddhi Impex has stocked super duplex SS coils in Mumbai since 2002, supplying buyers across India and exporting worldwide. Call or WhatsApp our team, and you'll have a quote within 24 hours.
