What is 254SMO Stainless Steel Pipe?
254SMO stainless steel pipe is a high-alloy super-austenitic stainless steel pipe engineered for extreme resistance to chloride-induced pitting,crevice corrosion,and stress corrosion cracking.It was originally developed by Outokumpu for use in aggressive halide environments like seawater and pulp mill bleach plants.
- 254SMO
- UNS S31254
- EN / DIN W.Nr. 1.4547
- ASTM / ASME Grade F44 / Grade FXM-11
- GB 015Cr20Ni18Mo6CuN
Chemical Composition of 254SMO Stainless Steel Pipe
The chemical composition of 254 SMO stainless steel pipe features high concentrations of chromium, nickel, nitrogen, and molybdenum, making it a classic super-austenitic stainless steel.
| Cr | Ni | Mo | N | Cu | C | Mn | Si | P | S | Fe |
|---|---|---|---|---|---|---|---|---|---|---|
| 19.5 – 20.5 | 17.5 – 18.5 | 6.0 – 6.5 | 0.18 – 0.22 | 0.50 – 1.00 | ≤ 0.020 | ≤ 1.00 | ≤ 0,80 | ≤ 0.030 | ≤ 0.010 | Équilibre |
Can The Chemical Composition of 254 SMO Degrade During Hot Work?
Oui.Because of the high chromium and molybdenum levels, 254SMO is highly sensitive to intermetallic phase precipitation (sigma phase) if held within the 600°C to 1000°C range.These phases deplete the surrounding metal of chromium and molybdenum,causing localized performance drops.To avoid this,a 254SMO stainless steel pipe must undergo solution annealing at 1150℃ to 1200℃,followed by an immediate water quench to lock the elements back into a uniform solid solution.
Mechanical Properties of 254SMO Stainless Steel Pipe
The mechanical properties of 254 SMOstainless steel pipe are characterized by exceptionally high yield strength and excellent ductility,outperforming standard 300-series austenitic stainless steels.These high values are achieved through interstitial nitrogen alloying rather than heat treatment.
According to ASTM A312 and ASTM A240 specifications,seamless and welded 254SMO pipes must meet the following minimum mechanical requirements at room temperature.
According to ASTM A312 and ASTM A240 specifications,seamless and welded 254SMO pipes must meet the following minimum mechanical requirements at room temperature.
| Mechanical Property | Résistance à la traction | Limite d'élasticité | Élongation | Dureté |
|---|---|---|---|---|
| 254SMO Super Stainless Steel | ≥ 650 MPa (94 ksi) | ≥ 300 MPa (44 ksi) | ≥ 35% | ≤ 223 HBW(96 HRB) |
In-Depth Analysis of Key Mechanical Behaviors
- Double the Yield Strength:
The minimum yield strength of 254SMO stainless steel pipe is nearly twice that of standard Tuyau en acier inoxydable 316L. - Exceptional Impact Toughness:
As a fully super-austenitic alloy,254 SMO does not exhibit a ductile-to-brittle transition temperature.It maintains remarkably high impact toughness and fracture resistance even at cryogenic temperatures reaching down to -196℃. - High Work-Hardening Rate:
The structural combination of high nickel and nitrogen causes the material to work-harden rapidly during cold forming operations.While this increases the pipe’s final burst strength,it demands high-power fabrication machinery and sharp tooling. - Elevated Temperature Derating:
While 254SMO retains solid mechanical stability up to 400℃,its design pressure ratings must be derated at higher temperatures due to a natural drop in yield strength.Prolonged exposure above 400℃ is not recommended due to the risk of embrittlement from sigma phase precipitation.
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- Plaque
- Feuille
- Forgeage
- Barre ronde
- Bride
- Tuyaux
- Raccords
- Sur mesure
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4 Manufacturing Methods for 254SMO Stainless Steel Pipe
Hot Piercing & Cold Pilgering
A seamless 254SMO stainless steel pipe manufacturing method.Solid billets are heated and pierced over a mandrel to form hollow shells.These shells undergo cold pilgering,where rolling dies and a tapered mandrel reduce the size.This achieves precise dimensions,smooth finishes,and excellent mechanical properties.
Hot Extrusion
A seamless 254SMO stainless steel pipe manufacturing method.Heated solid billets are placed in a container and forced through a die and over a mandrel using a hydraulic ram.This single-stroke compressive process prevents internal tearing,making it perfect for heavy-wall pipes and complex geometries.
Continuous Roll Forming & Welding
A welded 254SMO stainless steel pipe manufacturing method.Continuous 254 SMO coils are shaped into cylinders through progressive rollers.The longitudinal seam is joined using TIG or Plasma welding.Over-alloyed nickel-base filler wire (Alloy 625) is added to prevent corrosion-vulnerable alloy depletion in the weld seam.
Plate Press Brake & Fusion Welding
A welded 254SMO stainless steel pipe manufacturing method.Heavy 254 SMO plates are bent into “U” and “O” shapes using heavy-duty hydraulic presses.The seam is closed via multi-pass Electric Fusion Welding (EFW).This specialized method is reserved for large-diameter,heavy-wall industrial pipelines.
Manufacturing Standards for 254SMO Stainless Steel Pipe
- ASTM A312:This standard covers seamless and straight-seam welded super-austenitic pipes intended for high-temperature and general corrosive service.
- ASTM A358:It specifies electric-fusion-welded heavy-wall 254 SMO pipes suitable for corrosive,high-pressure,or elevated-temperature industrial applications.
- ASTM A790:This standard governs seamless and welded ferritic/austenitic pipes,ensuring strict dimensional tolerances and pressure ratings.
- EN 10217-7:This European standard defines technical delivery conditions for welded 254SMO pipes used specifically for pressure purposes.
- EN 10216-5:This European specification regulates seamless stainless steel pipes & tubes,mandating precise testing for pressure-bearing infrastructure.
- ASME B36.19M:It establishes the standard dimensions,schedules,and weight tolerances for welded and seamless stainless steel piping.
Applications of 254SMO Stainless Steel Pipe
- Réacteurs de traitement chimique
- Désulfuration des gaz de combustion
- Pulp and Paper Bleaching Plants
- Offshore Oil & Gas Platforms
- Seawater Desalination Plants
- Geothermal Energy Extraction
- Food and Beverage Processing
- Pharmaceutical and Biotech Equipment
- Coastal Power Station Cooling Systems
- Marine Exhaust Gas Cleaning
Our Capabilities Regarding 254SMO Stainless Steel Pipe
Excellence en matière de fabrication
Our production facility and supply chain infrastructure are fully equipped to manufacture,process,and supply high-quality 254 SMO stainless steel pipes.We strictly control every phase—from raw material melting to final non-destructive testing—to guarantee full compliance with global standards.
Approvisionnement et logistique
| Produit | Super Stainless Steel Pipes and tubes |
| Grade | 254SMO | UNS S31254 | DIN/EN 1.4547 | GB 00Cr20Ni18Mo6CuN |
| Dimension | 1/2″-24″ for seamless pipe, 1/2″-104″ for welded pipe |
| Calendrier | SCH10S, SCH20, SCH30, SCH40, STD, SCH80, XS, SCH60, SCH80, SCH120, SCH140, SCH160, XXS |
| Taper | Sans soudure / Soudé |
| Artisanat de fabrication | Hot Piercing & Cold Pilgering, Hot Extrusion, Continuous Roll Forming, Plate Press Brake & Fusion Welding |
| Extrémité du tuyau | Extrémité lisse, extrémité biseautée, profilée |
| Conditions de livraison | Recuit de solution, recuit brillant |
Assurance qualité
Our QA system ensures 254 SMO pipes deliver peak reliability in extreme chloride environments through rigorous,trace-to-source monitoring.We verify the 6% Moly chemical composition using advanced PMI testing.To guarantee structural integrity,pipes undergo 100% hydrostatic testing,automated ultrasonic/eddy current scans,and full radiographic weld inspections.Metallurgical audits—including ASTM G48 pitting and ASTM A262 intergranular corrosion tests—confirm successful solution annealing with zero brittle sigma phases.All shipments are dispatched with complete EN 10204 3.1 Material Test Certificates.
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