SMO 254 Pipes & Tubes

254 SMO Pipe is a high-alloy austenitic stainless steel pipe containing approximately 20% chromium, 18% nickel, 6.1% molybdenum, 0.7% copper and 0.20% nitrogen, with carbon held to 0.020% max. The high molybdenum-plus-nitrogen combination is what gives ASTM A312 UNS S31254 its exceptional pitting and crevice corrosion resistance in chloride-bearing and acidic media.

Key characteristics of SMO 254 Pipes & Tubes:

• Superior chloride resistance: Suitable for seawater, brackish water and desalination service.
• High strength: Minimum yield of 300 MPa, roughly double that of 316L, permitting thinner-wall design.
• Excellent toughness: Good impact strength and ductility at sub-zero as well as ambient temperature.
• Fully austenitic and non-magnetic: Magnetic permeability below 1.05.
• Readily weldable: Welded with over-alloyed nickel-base filler (Alloy 625 / C-276 type).
• Cost-efficient: A technically adequate substitute for nickel alloys and titanium at lower material cost. 

Note on service temperature: the grade contains no stabilising elements, so continuous service is normally limited to below approximately 400 °C (750 °F) to avoid sigma-phase and intermetallic precipitation. Hot working is performed in the 1150–1200 °C range.

Prices for 254 SMO pipe move with nickel and molybdenum LME rates, order quantity, form and certification. The table below is indicative only — request a live quote for firm pricing. 

Prices ex-Mumbai, exclusive of 18% GST for domestic supply. Payment terms: LC, TT / Wire Transfer, Cheque.

PREN (Pitting Resistance Equivalent Number) = Cr + 3.3 × Mo + 16 × N ≈ 43–45

A PREN above 40 is the accepted threshold for seawater service, which is why ASTM A312 UNS S31254 pipe is specified where 316L (PREN ~25) and 904L (PREN ~35) are inadequate.

Working pressures shown for annealed tubing at ambient temperature. De-rate for elevated temperature service per ASME B31.3.

Weight formula: (OD − WT) × WT × 0.0251 = kg/m (for 254 SMO, density 8.0 g/cm³). 👉 Use our Metal Weight Calculator for any size.

Also known as: 254 SMO®, 6-Moly, 6Mo Alloy, Alloy 254, AISI 254, Avesta 254 SMO, Sandvik 254 SMO.

Welding: 254 SMO pipe is readily welded by TIG, MIG, SMAW and plasma processes. Because molybdenum segregates during solidification, always use an over-alloyed nickel-base filler (ERNiCrMo-3 / Alloy 625 or ERNiCrMo-4 / C-276 type) to avoid loss of pitting resistance in the weld metal. Keep interpass temperature below 100 °C and heat input low. No pre-heat is required.

Heat Treatment: Solution anneal at 1150–1200 °C followed by rapid water quenching. Forging and hot upsetting is performed at 982–1149 °C. Post-fabrication solution annealing is strongly recommended to restore maximum corrosion resistance, particularly after cold work or pickling.

Machining: ASTM A312 UNS S31254 is tough to machine due to its low sulphur content and high work-hardening rate. Use sharp tooling, rigid setups, positive feeds and generous coolant. Speeds should be reduced roughly 40–50% versus 316L.

Cold Working: Cold forming is possible but requires higher forces because proof stress is high and elongation comparatively low. The grade can only be hardened by cold reduction; it does not respond to hardening by heat treatment. 

Tests performed: Ultrasonic testing, radiography, eddy current, hydrostatic testing, flaring test, flattening test, bend test, PMI (Positive Material Identification), spectro / chemical analysis, tensile and mechanical testing, hardness testing, IGC (ASTM A262 Practice E), pitting resistance test (ASTM G48), micro/macro examination, dimensional and visual inspection.

Certificates supplied:

• Manufacturer Test Certificate as per EN 10204 3.1 / 3.1B / 3.2
• Raw Material Certificate
• 100% Radiography Test Report
• Third-Party Inspection Report (TUV, DNV, PED, Lloyd’s, BV, SGS)
• Heat Treatment Charts
• Laboratory Test Certificate from Govt.-Approved Lab
• Form A (GSP), Fumigation Certificate, Commercial Invoice with HS Code

Marking: Every pipe is marked with Standard, Grade, OD, Thickness, Length, Heat No. — or as per customer requirement.

Packaging: Wooden boxes, wooden cases, wooden cartons, wooden pallets and shrink wrap, with plastic end caps to protect bevels during transit.

• Offshore & Marine: Seawater cooling systems, ballast lines, firewater mains, desalination plants, seawater pumps
• Oil & Gas: Sour service piping, umbilicals, topside process lines (NACE MR0175 / ISO 15156)
• Chemical & Petrochemical: Acid handling, reactors, chlorinated process streams
• Power Generation: Flue gas desulphurisation (FGD) scrubbers, condenser and heat exchanger tubes
• Pulp & Paper: Bleach plant washers, chlorine dioxide systems, tall oil distillation columns
• Food & Beverage Processing: Brewery piping, hot liquor tanks, evaporators, presses, sanitary tubing
• Pharmaceutical & Fertiliser Plants
• Pipeline & Plant Engineering, Mechanical Engineering, Aerospace
• Sugar Mills, Textile Machinery, Refineries, Automotive & Industrial Machinery

• SMO 254 Sheets & Plates
• SMO 254 Round Bar
• SMO 254 Fasteners
• SMO 254 Flanges
• SMO 254 Pipe Fittings