254 SMO Specifications | |
Institute | Standard |
ASTM | A182, A213, A249, A269, A276, A312, A358, A409 |
NFA | 49-217 |
EN | 10216-5, 10088-3 |
254 SMO is a high-alloy austenitic stainless steel known for its exceptional resistance to pitting, crevice corrosion, and stress corrosion cracking — especially in chloride-rich environments. With a high molybdenum content (about 6%) along with nickel, chromium, and nitrogen, 254 SMO offers superior strength and corrosion resistance compared to conventional stainless steels like 316L. It’s also highly weldable and maintains excellent mechanical properties even in demanding conditions. This alloy is widely used in applications where fasteners must endure aggressive environments such as seawater, brine systems, chemical processing plants, pulp and paper mills, and offshore oil and gas platforms. Bolts, nuts, washers, and studs made from 254 SMO provide reliable long-term performance in corrosive and high-pressure settings — reducing maintenance needs and extending equipment life.
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254 SMO Specifications | |
Institute | Standard |
ASTM | A182, A213, A249, A269, A276, A312, A358, A409 |
NFA | 49-217 |
EN | 10216-5, 10088-3 |
254 SMO Chemical Composition | |
Element | Percent Composition |
Nickel (Ni) | 17.5-18.0% |
Chromium (Cr) | 19.5-20.0% |
Molybdenum (Mo) | 6.0-6.5% |
Iron (Fe) | ~54.00% |
Copper (Cu) | 0.5-1.0% |
Manganese (Mn) | 1.0% Max |
Silicon (Si) | 0.80% Max |
Nitrogen (N) | 0.18-0.20% |
Carbon (C) | 0.02% Max |
Phosphorus (P) | 0.03% Max |
Sulfur (S) | 1.01% Max |
254 SMO Physical Properties | |
Density | 0.8 kg/dm³ |
Modulus of Elasticity | 195 GPa |
Thermal Conductivity | 14 w/m℃ |
Thermal Capacity | 500 J/kg℃ |
Electrical Resitivity | 0.85μΩm |
254 SMO Mechanical Properties | ||
Property | Sheet & Strip | Plate |
Tensile Strength | 100ksi / 690MPa | 95ksi / 655MPa |
Yield Strength 0.2% Offset | 45ksi / 310MPa | 45ksi / 310MPa |
Elongation (% in 50mm) min | 35 | 35 |
Hardness (Brinell) Max | 223 | 223 |
Hardness (Rockwell B) Max | 96 | 96 |
254 SMO is a high-alloy austenitic stainless steel specifically designed for exceptional resistance to pitting, crevice corrosion, and chloride stress corrosion cracking in aggressive environments.
Check out 254 SMO’s chemical composition:
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254 SMO exhibits outstanding corrosion resistance compared to other stainless steel alloys especially 316L. It has excellent resistance against standard uniform corrosion in acidic and chloride environments. The PREN value for 254 SMO is 42. This means that this is a good choice to be used in seawater and brine water environments. It also has great resistance against crevice corrosion due to its relatively high molybdenum content. Since it is an austenitic stainless steel with high amounts of Nickel, it resists stress cracking better than 300 series stainless steels. It also resists intergranular corrosion due to its low carbon content and solution-annealed condition. It resists galvanic corrosion well. However if coupled with a lesser noble alloy, it can can cause galvanic corrosion in that material.
Corrosion Comparison between 316, Duplex 2205, & 254 SMO | |||
Corrosion Type | 254 SMO | ||
Uniform | Fair | Good | Excellent |
Pitting | Poor | Good | Exceptional |
Crevice | Poor | Good | Exceptional |
SCC | Poor | Moderate | Excellent |
Galvanic | Moderate | Good | Excellent |
Intergranular | Moderate | Good | Excellent |
Fretting | Moderate | Good | Moderate ~ Good |
254 SMO has exceptional mechanical strength compared to typical austenitic stainless steels. Its yield strength is approximately 45ksi and its tensile strength is 94ksi to 102ksi. 254 SMO can also be work hardened and cold formed. These adds significant strength without any heat treatments.
Marine industries use 254 SMO fasteners in their offshore platforms, subsea equipment, & seawater intake systems. Some fastener examples used include hex head cap screws, heavy hex nuts, flat washers and stud bolts. 254 SMO wedge washers are used in desalination frame supports to prevent vibration and saltwater corrosion. 254 SMO fasteners preform well and withstand corrosion due to saltwater environments.
Chemical processing plants use socket head shoulder screws, threaded bolts, and double-end studs in agitator mounting systems, chemical feed line manifolds, and tank restraint systems. SMO fasteners do exceptionally well in acidic and halide-rich environments.
The oil and gas industry uses socket head cap screws and flange hex screws to fasten subsea valve body fastening, Christmas tree and wellhead flange assembly, and downhole pressure housings. This industry uses 254 SMO fasteners
The pulp and paper industry use 254 SMO hex head bolts, nuts and washers for piping and ventilation duct mounting. These fasteners withstand oxidation media well.
The power generation industries use 12-point flange screws to secure heat exchanger baffles and heads. The pressure and heat does not greatly affect the corrosion resistance or mechanical strength of the 254 SMO fasteners.
254 SMO is a high-performance super austenitic stainless steel alloy engineered for extreme corrosion resistance, high strength, and long-term durability in the harshest environments. From offshore platforms and desalination plants to chemical processing and pharmaceutical systems, its ability to withstand aggressive chlorides, acids, and elevated pressures makes it the material of choice for mission-critical fasteners and assemblies. Whether you’re facing challenges in seawater exposure, chemical attack, or high-stress industrial conditions, 254 SMO offers proven reliability where standard stainless steels fall short.
To ensure optimal performance and compliance in your next project, contact Nickel Systems Inc. today to begin your custom quote for 254 SMO fasteners or fittings.
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