SMO 254 fasteners, manufactured from a super austenitic stainless steel, represent the pinnacle of performance for critical applications demanding exceptional corrosion resistance and high strength. Also known as UNS S31254 or simply 254 SMO fastener, this alloy is the go-to choice for combating aggressive chemical and marine environments.

Complete Chemical Composition (Key Elements):

The outstanding properties of SMO 254 fastener material stem from its precisely balanced, full chemical composition:

• Chromium (Cr): 19.5 - 20.5% - Provides a stable passive oxide layer for base corrosion resistance.

• Nickel (Ni): 17.5 - 18.5% - Stabilizes the austenitic structure and enhances ductility.

• Molybdenum (Mo): 6.0 - 6.5% - The critical element for supreme resistance to pitting and crevice corrosion.

• Copper (Cu): 0.5 - 1.0% - Improves resistance to sulfuric acid.

• Nitrogen (N): 0.18 - 0.22% - Significantly increases mechanical strength and stability.

• Manganese (Mn): ≤ 1.0%

• Silicon (Si): ≤ 0.8%

• Phosphorus (P): ≤ 0.030%

• Sulfur (S): ≤ 0.010%

• Iron (Fe): Balance.

Mechanical Properties of SMO 254 Fastener Material:

SMO 254 fasteners offer a superior combination of strength and toughness:

• Tensile Strength: ≥ 650 MPa

• Yield Strength (0.2% Offset): ≥ 300 MPa

• Elongation: ≥ 35%

• Hardness (Typical): ≤ 223 HB (Brinell) / ≤ 96 HRB (Rockwell B)

• High PREN Value: > 43 (Pitting Resistance Equivalent Number, calculated as %Cr + 3.3(%Mo) + 16(%N)), guaranteeing excellent performance in chloride-rich settings.

Primary Application Fields:

SMO 254 industrial fasteners are indispensable in sectors where failure is not an option:

• Offshore & Marine: For saltwater resistant fasteners in seawater cooling systems, ballast tanks, and offshore oil & gas platforms.

• Chemical Processing (CPI): In reactors, heat exchangers, and piping handling sulfuric acid, phosphoric acid, chlorides, and other aggressive chemicals.

• Pollution Control & FGD Systems: In flue gas desulfurization (FGD) units and scrubbers.

• Pulp & Paper Industry: Especially in digesters and bleaching equipment.

• Pharmaceutical & Food Processing: Where high purity and corrosion resistance are paramount.

Classification of SMO 254 Fasteners and Their Specific Applications:

1. SMO 254 Bolts, Stud Bolts, and Nuts:

   • Application: Used for high-integrity flange connections in pressure vessel flanges, pipeline flanges, and heat exchanger designs within chemical plants and seawater systems. Hex bolts and heavy hex nuts are common here.

     
     

2. SMO 254 Screws (Machine Screws, Socket Head Cap Screws):

   • Application: Ideal for precision equipment, pumps, and valve assemblies requiring a secure, corrosion-resistant fastening point. Alloy 254 SMO socket screws offer high tensile strength for compact designs.

     
     

3. SMO 254 Washers (Flat Washers, Spring Washers):

   • Application: Used in conjunction with bolts and nuts to distribute load and prevent loosening under vibration in marine hardware and offshore structural connections.

     
     

4. SMO 254 Threaded Rods and Studs:

   • Application: Serve as essential fastener components for constructing modular systems, lining tanks, or as continuous threading for custom assembly in chemical processing units.

     
     

5. Specialty SMO 254 Fasteners:

   • Application: This includes U-bolts, anchor bolts, and eye bolts designed for specialized securing, lifting, and mooring applications in harsh environments.

Why Choose Our SMO 254 Fasteners?

Our high-performance stainless steel fasteners in UNS S31254 are produced to the strictest international standards (ASTM / ASME, DIN, ISO). We are a leading supplier of corrosion resistant fasteners and high strength fasteners for engineering solutions worldwide. For your most demanding applications—from seawater resistant bolting to chemical plant fasteners—specify premium SMO 254 alloy fasteners for unmatched reliability and longevity.

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