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What is Stainless Steel 310S?

310S Stainless Steel Pipe 310S (UNS S31008) is an austenitic stainless steel of the "25/20" family - about 25% chromium and 20% nickel. The high chromium-nickel balance gives it excellent high-temperature strength and outstanding resistance to oxidation, scaling, carburization and sulfidation. The "S" denotes the low-carbon version of grade 310 (carbon ≤0.08% vs ≤0.25% for 310), which makes 310S the preferred, weld-friendly grade for fabricated high-temperature equipment. It is non-magnetic in the annealed condition and retains good toughness even at cryogenic temperatures.

About 310S Stainless Steel Pipe

Chemical composition (ASTM A312 TP310S)

Element	310S (S31008), % max unless noted
Carbon (C)	≤ 0.08
Manganese (Mn)	≤ 2.00
Phosphorus (P)	≤ 0.045
Sulfur (S)	≤ 0.030
Silicon (Si)	≤ 1.00
Chromium (Cr)	24.00 – 26.00
Nickel (Ni)	19.00 – 22.00
Molybdenum (Mo)	≤ 0.75
Iron (Fe)	Balance

Mechanical properties

Property	310S (S31008)
Tensile strength	≥ 515 MPa (75 ksi)
Yield strength (0.2% offset)	≥ 205 MPa (30 ksi)
Elongation (in 50 mm)	≥ 40%
Hardness, Brinell (max)	≤ 217 HB
Hardness, Rockwell B (max)	≤ 95 HRB

Physical properties

Property	Value
Density	8.0 g/cm³ (0.289 lb/in³)
Melting point	≈ 1454–1455 °C (2650 °F)
Modulus of elasticity	≈ 200 GPa (29 × 10⁶ psi)
Thermal conductivity (≈ room temp)	≈ 14.2 W/m·K
Coefficient of thermal expansion	≈ 15.5 × 10⁻⁶ /K (typical)
Magnetic?	No (annealed); slightly magnetic after cold work

Equivalent grades

Standard	Designation
UNS	S31008
EN / DIN (Werkstoff)	1.4845
EN name	X8CrNi25-21
JIS	SUS 310S
BS (old)	310S16
GOST	20Ch23N18 (20Х23Н18)
AFNOR	Z8CN25-21

Standards & specifications

Product form	ASTM / ASME standard
Seamless & welded pipe	ASTM A312 / ASME SA312 (TP310S)
Seamless tube	ASTM A213 (TP310S)
Welded tube	ASTM A249 (TP310S)
Welded & sanitary tube	ASTM A269 / A270
Electric-fusion-welded (EFW) pipe	ASTM A358 (TP310S, Class I–V)
Plate, sheet, strip	ASTM A240 / ASME SA240 (310S)
Forged flanges & fittings	ASTM A182 (F310S)
Welded fittings	ASTM A403 (WP310S)
Bar & rod	ASTM A276 / A479

Available sizes & dimensions

Seamless pipe: 1/2" – 18" NB (up to 48" NB on request).

Welded / ERW pipe: 1/2" – 16" NB.

EFW pipe: 8" – 110"+ NB.

Wall thickness: SCH 5, SCH10, SCH 40, SCH 80, SCH 80S, SCH 160, SCH XXS, SCH XS.

Length: up to 12 m, cut-to-length and random lengths available.

Types: Welded, Seamless, EFW, Fabricated, ERW.

Finishes: 2B, BA, No.4, No.1, No.8 Mirror Finish or custom.

High-temperature performance

Condition	Maximum service temperature
Continuous service (oxidation)	up to ≈ 1150 °C (2100 °F)
Intermittent service	up to ≈ 1040 °C (1900 °F)
Typical operating start point	≈ 800–900 °C and above

310S Heat Treatment

Corrosion resistance

Excellent resistance to oxidation, scaling, carburization and sulfidation at elevated temperature.

Good aqueous corrosion resistance in non-chloride media thanks to high chromium.

Resists sulfur dioxide and other hot gases; widely used where SO₂ is encountered.

PREN ≈ 25 (similar to 316L) - but it is NOT a seawater/marine grade and is susceptible to chloride pitting and stress-corrosion cracking like other austenitics.

Weldability & fabrication

310S welds readily by common processes (GTAW, GMAW, SMAW, SAW), with weldability comparable to 304/304L. Use matched filler metal such as ER310 / E310, or ER309 for dissimilar joints. Because 310S has a higher coefficient of thermal expansion than 304, control heat input and fixturing to minimize distortion and warping. Severe cold forming should be followed by annealing.

310S Stainless Steel Pipe Manufacturing Process

Raw Material Inspection → Cutting → Piercing / Forming → Hot Rolling or Cold Drawing → Heat Treatment → Pickling → Straightening → Cutting → Dimensional Inspection → PMI Testing → Hydrostatic Testing → Marking → Packaging

310S Stainless Steel Pipe Manufacturing Process

Typical Applications

Furnace & Heat Treatment: Furnace tubes, radiant tubes, furnace chambers, retorts, annealing equipment

Petrochemical Industry: Cracking furnace tubes, process heaters, high-temperature piping, refinery equipment

Power Generation: Boiler components, superheater components, thermowells, gas turbine components

Waste Incineration: Incinerator tubes, combustion chambers, high-temperature exhaust systems

factory pipe line

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Quality Inspection And Inspection Documents

Quality Inspection	Inspection Documents
PMI / Positive Material Identification	EN 10204 3.1 Certificate
Chemical Composition Testing	Mill Test Certificate
Tensile Testing	PMI Report
Yield Strength Testing	Hydrostatic Test Report
Elongation Testing	Dimensional Inspection Report
Hardness Testing	NDT Report
Hydrostatic Testing
Eddy Current Testing
Ultrasonic Testing
Dimensional Inspection
Visual Inspection
Surface Inspection

310S vs 304 vs 316L vs 309S-what is the difference?

Property	304	316L	309S	310S
Cr	~18–20%	~16–18%	~22–24%	~24–26%
Ni	~8–11%	~10–14%	~12–15%	~19–22%
High-temperature resistance	Medium	Medium	High	Very High
Oxidation resistance	Good	Good	Excellent	Excellent
Chloride resistance	Good	Better	Moderate	Moderate
Typical use	General industry	Chemical / marine	High-temperature	Furnace / heat treatment

FAQ

What is Stainless Steel 310S pipe used for?

310S pipe is used wherever sustained high temperature and oxidation/carburization resistance are required: furnaces, radiant tubes, heat exchangers, burners, kilns, incinerators, petrochemical heaters and refining/cracking units. It is a high-heat grade, not a marine grade.

What temperature can 310S stainless steel withstand?

Up to about 1150 °C (2100 °F) in continuous oxidation service and about 1040 °C (1900 °F) in intermittent service. It generally performs from roughly 800–900 °C upward, outperforming 304 and 309.

What is the difference between 310 and 310S?

310S is the low-carbon version of 310 (≤0.08% vs ≤0.25% C). The lower carbon avoids sensitization and intergranular corrosion after welding, making 310S the standard for welded fabrications, while higher-carbon 310 has slightly stronger creep resistance for high-stress high-temperature parts.

Is 310S stainless steel good for seawater or marine use?

No. 310S is optimized for high-temperature oxidation and carburization, not chloride resistance. It is susceptible to pitting and chloride stress-corrosion cracking like other austenitics. For seawater/marine service use 316L at minimum, and super duplex 2507 or 6Mo 254 SMO for continuous seawater.

Which ASTM standards cover 310S pipe?

Pipe: ASTM A312 / ASME SA312 (TP310S); EFW pipe ASTM A358; tube ASTM A213/A249/A269; plate ASTM A240; forged flanges/fittings ASTM A182 F310S; welded fittings ASTM A403 WP310S. (ASTM A789/A790 do NOT apply - those are duplex-only.)

What filler metal is used to weld 310S?

Matched filler such as ER310 / E310 is typical; ER309 is often used for dissimilar joints. Control heat input because of 310S's higher thermal expansion, and anneal after severe forming.

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