254 SMO Flanges
254 SMO Flanges (UNS S31254 / 1.4547)
254 SMO Stainless Steel Flanges (UNS S31254) are high-alloy austenitic stainless steel components designed for extreme corrosion resistance in chloride-rich and seawater environments. Known for their exceptional strength, toughness, and stress corrosion cracking resistance, 254 SMO flanges are widely used in chemical processing, offshore, and marine applications.
At Emirerri Steel, we manufacture and supply premium-quality 254 SMO flanges that comply with ASTM A182 / ASME SA182 standards, ensuring unmatched reliability in harsh industrial conditions.
Key Features
Excellent resistance to pitting and crevice corrosion
Superior chloride stress corrosion cracking resistance
High tensile strength and good weldability
Performs exceptionally in acidic and saline environments
Excellent formability and ductility
Low carbon content minimizes carbide precipitation during welding
Outstanding resistance to oxidation and scaling
Type of Flanges 254 SMO Flanges
Specification
| Specification | Details |
|---|---|
| Standard | ASTM A182 / ASME SA182 |
| Grade | 254 SMO |
| UNS Number | S31254 |
| EN/DIN | 1.4547 |
| Form | Forged / Rolled Flanges |
| Pressure Class | 150#, 300#, 600#, 900#, 1500#, 2500# |
| Size Range | ½” NB to 48” NB |
| Dimensions | ASME B16.5, B16.47, DIN, EN, JIS, GOST |
| Manufacturing Process | Forging / CNC Machining / Heat Treated |
| Surface Finish | Smooth / Serrated / Spiral Serrated |
Equivalent Grades
| Standard | Equivalent Grade |
|---|---|
| UNS | S31254 |
| EN | 1.4547 |
| AFNOR | Z1 CNDU 20-18-06 |
| BS | 254 SMO |
| JIS | SUS312L |
| Trade Name | Avesta 254 SMO®, Sandvik 254 SMO® |
Available Sizes
Flange Range: ½” NB to 48” NB
Forged Fittings: ⅛” to 4”
Custom Designs: As per drawings or project specifications
Chemical Composition
| Element | Percentage (%) |
|---|---|
| Carbon (C) | 0.020 max |
| Manganese (Mn) | 1.00 max |
| Silicon (Si) | 0.80 max |
| Phosphorus (P) | 0.030 max |
| Sulfur (S) | 0.010 max |
| Chromium (Cr) | 19.50 – 20.50 |
| Nickel (Ni) | 17.50 – 18.50 |
| Molybdenum (Mo) | 6.00 – 6.50 |
| Nitrogen (N) | 0.18 – 0.22 |
| Iron (Fe) | Balance |
Mechanical Properties
| Property | Unit | Value |
|---|---|---|
| Tensile Strength | MPa | 650 min |
| Yield Strength (0.2% Proof) | MPa | 300 min |
| Elongation | % | 35 min |
| Hardness (Brinell) | HB | 270 max |
| Impact Toughness | J | 100 (typical) |
Physical Properties
| Property | Unit | Value |
|---|---|---|
| Density | g/cm³ | 8.0 |
| Melting Point | °C | 1320 – 1390 |
| Thermal Conductivity | W/m·K | 14.0 at 20°C |
| Electrical Resistivity | µΩ·m | 0.95 |
| Modulus of Elasticity | GPa | 195 |
| Specific Heat | J/kg·K | 500 |
Corrosion Resistance
254 SMO stainless steel is specifically engineered for severe chloride environments. It provides:
Excellent pitting and crevice corrosion resistance, with a PREN > 42
Superior performance in seawater, brackish water, and acidic chloride solutions
Excellent resistance to stress corrosion cracking and sulphide stress corrosion
This makes it ideal for offshore platforms, desalination plants, and chemical industries.
Heat Resistance
254 SMO offers good oxidation resistance up to 1100°F (600°C). Continuous exposure above this temperature is not recommended due to potential phase precipitation, but it performs well in intermittent high-temperature conditions.
Heat Treatment
Solution Annealing: 1150 – 1200°C followed by rapid water quenching
This restores corrosion resistance and mechanical properties after fabrication.
No further hardening occurs through heat treatment; however, cold working increases strength.
Welding
254 SMO can be welded using conventional methods like TIG, MIG, and SMAW.
Recommended Filler Metals: ERNiCrMo-3 (Alloy 625) or ERNiCrMo-4
Preheating: Not required
Post-Weld Heat Treatment: Not necessary, but solution annealing may be performed for maximum corrosion resistance
Welds exhibit excellent toughness and corrosion resistance, provided low heat input and interpass temperatures are maintained.
Fabrication
254 SMO can be cold-formed and hot-formed using standard stainless steel techniques.
Hot Forming Temperature: 1150°C to 950°C
Forging: Followed by rapid cooling or quenching
Machinability: Slightly lower than austenitic grades like 316L due to high strength and work hardening rate.
Proper lubrication and slow feeds enhance machinability.
Applications
Desalination Plants (Evaporators, Pumps, and Flanges)
Offshore Oil & Gas Platforms
Chemical and Petrochemical Processing Equipment
Pulp and Paper Industry (Bleaching Plants)
Heat Exchangers and Condensers
Marine Engineering Components
Food Processing Equipment
Seawater Cooling Systems
Pharmaceutical & Environmental Equipment