ASTM A182 F51 Slip On Flange | Duplex Stainless Steel SORF / SOFF Flange
What Is ASTM A182 F51 Slip On Flange?
ASTM A182 F51 slip on flange is a duplex stainless steel flange designed for corrosion-resistant and high-strength piping systems. Manufactured according to ASME B16.5 dimensional standards, this flange type is commonly used in oil & gas, offshore platforms, chemical processing plants, and desalination systems.
Slip on flanges are also referred to as SORF (Slip On Raised Face) or SOFF (Slip On Flat Face) flanges depending on the sealing surface design.
Duplex ASTM A182 F51, equivalent to UNS S31803 / S32205, provides excellent resistance to pitting corrosion, crevice corrosion, and chloride stress corrosion cracking, making it suitable for harsh industrial environments.
ASTM A182 F51 slip on flanges, including SORF (Slip On Raised Face) and SOFF (Slip On Flat Face) types, are duplex stainless steel flanges manufactured for moderate to high-pressure piping systems requiring good strength and corrosion resistance. Produced in accordance with ASTM A182 material specification and ASME B16.5 dimensional standard, F51 flanges provide an excellent balance of mechanical strength, corrosion resistance, and cost efficiency.
ASTM A182 F51 slip on flanges are widely used in oil & gas, offshore, chemical processing, water treatment, and desalination applications.
Flange Types – Slip On Flange
🔹 SORF – Slip On Raised Face Flange
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Raised face sealing surface
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Used with spiral wound or soft gaskets
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Common for oil, gas, and chemical piping
🔹 SOFF – Slip On Flat Face Flange
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Flat sealing surface
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Typically used with flat face gaskets
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Preferred for systems with cast iron equipment or lower pressure
Slip on flanges are welded on both the inside and outside of the pipe, providing secure attachment and easy alignment during installation.
Size Range & Pressure Class (ASME B16.5)
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Nominal Pipe Size (NPS): 1/2″ – 24″
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Pressure Class: 150 / 300 / 600 / 900 / 1500
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Facing Types: RF (SORF) / FF (SOFF)
Chemical Composition – ASTM A182 F51 (Typical, wt %)
| Element | Content |
|---|---|
| Chromium (Cr) | 21.0 – 23.0 |
| Nickel (Ni) | 4.5 – 6.5 |
| Molybdenum (Mo) | 2.5 – 3.5 |
| Nitrogen (N) | 0.08 – 0.20 |
| Carbon (C) | ≤ 0.03 |
| Manganese (Mn) | ≤ 2.0 |
| Silicon (Si) | ≤ 1.0 |
| Phosphorus (P) | ≤ 0.035 |
| Sulfur (S) | ≤ 0.020 |
| Iron (Fe) | Balance |
Mechanical Properties (Room Temperature – Typical)
| Property | Requirement |
|---|---|
| Tensile Strength | ≥ 620 MPa |
| Yield Strength (0.2%) | ≥ 450 MPa |
| Elongation | ≥ 25% |
ASTM A182 F51 Heat Treatment
ASTM A182 F51 slip on flanges are supplied in solution annealed condition, followed by rapid cooling to ensure proper duplex microstructure and optimal corrosion resistance.
Testing & Inspection
ASTM A182 F51 flanges undergo strict quality control, including:
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Chemical analysis
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Tensile testing
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Ferrite content testing
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Dimensional inspection
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Visual inspection
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Optional NDT (UT / MT / PT)
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Certification: EN 10204 3.1 / 3.2
Applications of ASTM A182 F51 Slip On Flanges
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Offshore and onshore oil & gas pipelines
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Chemical and petrochemical processing plants
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Seawater and desalination systems
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Water treatment facilities
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Heat exchangers and pressure piping
ASTM A182 F51 slip on flanges (SORF / SOFF) manufactured to ASME B16.5 provide a reliable and cost-effective solution for corrosion-resistant piping systems. With higher strength than austenitic stainless steel and excellent resistance to chloride environments, duplex F51 slip on flanges are widely trusted in oil & gas, chemical, and marine applications.
We supply high-quality ASTM A182 F51 duplex stainless steel slip on flanges manufactured according to ASME B16.5 standards.
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