What are the specifications of SS 904L Seamless Pipe?

Available in UNS N08904 (ASTM A312 TP904L), OD 1/2"-20" NB, Sch 5S-80S, hot finished or cold drawn seamless construction, carbon held to 0.020% max.

When is 904L preferred over standard 316L?

904L is preferred in more aggressive sulfuric/phosphoric acid or chloride environments where 316L's corrosion resistance is insufficient, particularly where copper's benefit against reducing acids matters.

Why does 904L contain copper when most stainless grades don't?

Copper specifically improves resistance to reducing acids like dilute sulfuric acid, complementing the chromium/molybdenum-driven resistance to oxidizing conditions that most austenitic grades rely on.

Is 904L considered a duplex alternative?

No - 904L is fully austenitic (not duplex), offering excellent weldability and toughness; it's often compared against duplex 2205 as an alternative super-austenitic option depending on the specific corrosive service.

Does Sakshi Forge provide Material Test Certificates (MTC) for SS 904L Seamless Pipe?

Yes, MTC as per EN 10204 3.1 is provided with every dispatch along with inspection reports.

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SS 904L Seamless Pipe - Super Austenitic Corrosion Resistant Pipe | Sakshi Forge

Super-Austenitic Ni-Mo-Cu Stainless Steel Pipe for Sulfuric Acid and Severe Chloride Service

High Nickel (23-28%) + Copper (1-2%) for supreme resistance to sulfuric and phosphoric acids

High PREN (≥35) and high nickel content resist chloride pitting and stress corrosion cracking

Ultra-low carbon (≤0.020%) ensures excellent post-weld intergranular corrosion resistance

EN 10204 3.1 MTC100% PMI TestedISO 9001:2015 CertifiedHydrostatic Tested

Hygienic Steel Grade

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MTC EN 10204 3.1 Included

Global Sea & Air Freight

Electro-Chemical Finish Certificate

Response turnaround: Under 2 hours

Product Profile

SS 904L (UNS N08904 / ASTM A312 TP904L) is a high-alloy super-austenitic stainless steel seamless pipe engineered for extreme resistance to sulfuric, phosphoric, and organic acids across a broad range of temperatures and concentrations. Its chemistry features high nickel (23.0%-28.0%), high chromium (19.0%-23.0%), molybdenum (4.0%-5.0%), and a deliberate copper addition (1.0%-2.0%). The copper content specifically imparts outstanding resistance to reducing acids like dilute sulfuric acid-an environment where standard 316L and 304L fail rapidly. Furthermore, 904L's high nickel content provides immunity to chloride-induced stress corrosion cracking (SCC), while its high PREN (≥35) delivers excellent resistance to pitting and crevice corrosion in marine and brine media. With a ultra-low carbon ceiling (≤0.020%), 904L seamless pipe can be welded without risk of intergranular carbide precipitation. Sakshi Forge supplies fully solution-annealed and passivated SS 904L seamless pipes for fertilizer plants, flue-gas desulfurization (FGD) scrubbers, chemical processing reactors, and seawater piping.

Terminology & Abbreviations

UNS N08904|N08904

Werkstoff 1.4539|1.4539

904L Super Austenitic|904L

ASTM A312 TP904L|TP904L

Key Technical Facts

Alloyed with 23-28% Nickel, 19-23% Chromium, 4-5% Molybdenum, and 1-2% Copper

Copper addition provides unmatched corrosion resistance in reducing acids (sulfuric, phosphoric, formic)

High nickel matrix prevents chloride stress corrosion cracking (SCC) in brackish and brine waters

Pitting Resistance Equivalent Number (PREN ≥ 35) offers superior pitting resistance over 316L

Ultra-low carbon (C ≤ 0.020%) eliminates intergranular corrosion risks during heavy-section welding

Fully austenitic microstructure maintains high impact toughness down to cryogenic temperatures (-196°C)

Manufactured seamless via hot extrusion and cold drawing per ASTM A312 Grade TP904L

Supplied solution annealed at 1080-1150°C and water quenched with full EN 10204 3.1 certification

Why Choose Sakshi Forge

Our commitment to sterile, high-purity processing makes us a trusted manufacturing partner globally.

100% Heat Lot Traceability

Every pipe stamped with heat number matching EN 10204 3.1 MTC

Positive Material Identification (PMI)

Handheld XRF testing on every length prior to dispatch

Advanced NDT Inspection

Hydrostatic test and Eddy Current / Ultrasonic flaw detection on all orders

Precision Cold Drawing

Tighter wall thickness tolerances and superior internal bore smoothness

Custom Cut Lengths

Fixed lengths up to 12 meters or custom cut-to-length options to eliminate jobsite scrap

Ferrite & Phase Balance Testing

Ferritescope testing for duplex and super duplex grades to ensure 40-60% phase balance

High-Temperature Stabilization

Controlled heat treatment to fully precipitate carbides and optimize creep life

Pan-India & Export Freight

Fast dispatch across India and seaworthy export packing for global projects

Extensive Mill Stocking

Immediate inventory availability in standard schedules from Sch 10S to Sch 160

Third-Party Inspection Approved

Full support for TUV, SGS, DNV, Bureau Veritas, and Lloyds audits

Frequently Asked Questions

Common technical and pricing queries regarding specifications and ordering.

SS 904L seamless pipe is specified under UNS N08904 / ASTM A312 TP904L. It features 23-28% Nickel, 4-5% Molybdenum, and 1-2% Copper for maximum acid and chloride resistance.

Partner with Sakshi Forge for Reliable Industrial Steel Solutions

Delivering precision-engineered flanges, pipes, and forged steel components designed for strength, durability, and performance in critical high-pressure industrial applications.