SS 904L Pipe Fittings
Teshi Group manufactures SS 904L pipe fittings (ASTM A403 WP904L, A182 F904L, UNS N08904) as an OEM in India — butt weld fittings to ASME B16.9 and forged socket weld and threaded fittings to ASME B16.11, with heat-number traceability on every piece.
Super austenitic stainless steels combine high nickel, molybdenum and copper (904L) or 6 % molybdenum with nitrogen (254 SMO) to resist sulphuric and phosphoric acid, chloride pitting and stress corrosion cracking.
SS 904L pipe fittings at a glance
| Material | SS 904L |
|---|---|
| Specification | Butt weld: ASTM A403 WP904L · Forged: ASTM A182 F904L |
| UNS / W.Nr. | N08904 / 1.4539 |
| Sizes | Butt weld NPS ½"–48", Sch 5S–XXS · Forged NPS ⅛"–4" |
| Pressure class | Wall to pipe schedule (B16.9) · Class 2000, 3000, 6000, 9000 (B16.11) |
| Facing / ends | Bevelled ends to ASME B16.25; socket weld and NPT threaded ends |
| Certification | EN 10204 3.1 standard · 3.2 with third-party inspection · IBR on request |
| Testing | PMI, hardness, dimensional; UT, IGC, impact and ferrite as specified |
SS 904L chemistry and mechanical properties
Chemical composition of SS 904L (weight %, maximum unless a range)
| Grade | C | Mn | Si | Cr | Ni | Mo | Cu | N |
|---|---|---|---|---|---|---|---|---|
| 904L | 0.020 | 2.00 | 1.00 | 19.0–23.0 | 23.0–28.0 | 4.0–5.0 | 1.00–2.00 | 0.10 |
Mechanical properties of SS 904L (minimum, room temperature)
| Grade | Tensile strength | Yield strength (0.2 %) | Elongation | Note |
|---|---|---|---|---|
| 904L | 490 MPa (71 ksi) | 215 MPa (31 ksi) | 35 % | PREN ≈ 34 |
Matching specifications by product form
| Grade | Forged flanges & fittings | Butt weld fittings | Plate | Pipe |
|---|---|---|---|---|
| 904LUNS N08904 · W.Nr. 1.4539 | ASTM A182 F904L | ASTM A403 WP904L | ASTM A240 / B625 | ASTM A312 / B677 |
Limits and minimums from the governing ASTM / ASME specifications, summarised for convenience; the current edition takes precedence.
Pressure rating
Butt weld fittings carry the same pressure rating as straight seamless pipe of the same material and wall thickness, so the fitting schedule is matched to the line pipe (ASME B16.9). Forged socket weld and threaded fittings are rated by class — 3000 and 6000 for socket weld, 2000, 3000 and 6000 for threaded — per ASME B16.11.
Types we manufacture
Dimension charts
Where SS 904L is used
- Sulphuric acid dilution, cooling and storage
- Zinc and copper smelter roaster gas cleaning and leaching circuits
- Phosphoric acid evaporators
- Flue-gas desulphurisation scrubbers
- Seawater and brackish cooling water
Testing & certification
- Solution annealed and water quenched
- PMI on every piece for Ni, Mo and Cu
- Intergranular corrosion test to ASTM A262 when specified
- EN 10204 3.1 certificate; 3.2 with third-party inspection on request
FAQ
SS 904L pipe fittings: common questions
What specification covers SS 904L pipe fittings?
SS 904L butt weld fittings are made to ASTM A403 WP904L with dimensions to ASME B16.9; forged socket weld and threaded fittings are made to ASTM A182 F904L with dimensions to ASME B16.11.
What is the chemical composition of 904L?
904L (UNS N08904): C 0.020, Mn 2.00, Si 1.00, Cr 19.0–23.0, Ni 23.0–28.0, Mo 4.0–5.0, Cu 1.00–2.00, N 0.10 (weight %; single values are maximums).
What are the minimum mechanical properties of 904L?
Tensile strength 490 MPa (71 ksi), yield strength 215 MPa (31 ksi), elongation 35 %.
Is Teshi Group a manufacturer of SS 904L pipe fittings in India?
Yes. Teshi Group has manufactured flanges and fittings in India since 1971 and is ISO 9001:2015 certified and IBR approved. Every SS 904L piece is hard-stamped with its heat number and supplied with an EN 10204 3.1 certificate; 3.2 with third-party inspection on request.
Why is SS 904L used in sulphuric acid plants?
904L (UNS N08904) has 23–28 % nickel, 4–5 % molybdenum and 1–2 % copper, which give good resistance to dilute and moderately concentrated sulphuric acid at temperatures where 316L corrodes quickly.
What is the difference between 904L and 254 SMO?
904L relies on nickel and copper for acid resistance. 254 SMO (UNS S31254, ASTM A182 F44) has 6 % molybdenum and 0.18–0.25 % nitrogen, giving a PREN above 42 and much better resistance to chloride pitting and crevice corrosion.
Super austenitic stainless steel grade data sheets
Super austenitic stainless steel overview →Chemical composition, mechanical properties and PDF data sheet for each grade.
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