Stainless Steel 310 Pipe Fittings are specified where the line runs hot enough to scale ordinary 304 or 316. Grade 310 carries about 25% chromium and 20% nickel, and that chemistry holds a protective oxide layer in air at temperatures where lower grades start to flake. It is a heat grade. Some buyers order it for wet corrosion or sour gas, which it was not built for, and then pay more for a fitting that does no more. Metinox Overseas supplies 310 and 310S buttweld and forged fittings to furnace, refinery and power plant buyers in India, the GCC and other export markets, as part of our range of pipe fittings.
Request a QuotationTable of Contents
- SS 310S vs 310H vs 310 Pipe Fittings
- SS 310 Pipe Fittings Specification
- Types of 310 Stainless Steel Buttweld Fittings and Forged Fittings
- Chemical Composition of SS 310 / 310S Pipe Fittings
- Mechanical Properties of ASTM A403 WP310S and A182 F310 Fittings
- Physical Properties of 310 Stainless Steel
- Stainless Steel 310 Grade Pipe Fittings Equivalent Designations
- Stainless Steel 310 Buttweld Fittings Size Chart: ASME B16.9 Dimensions
- Wall Thickness by Schedule for SS 310 Grade Fittings (ASME B36.19M / B36.10M)
- Applications of SS 310S Pipe Fittings
- What Drives the Price of SS 310S Buttweld Fittings
- Request a Quote for Stainless Steel 310 Pipe Fittings
- Complete the Line: Pipe, Fitting and Flange in Grade 310S
- Buyer Questions on SS 310S Fittings for GCC and Export Orders
SS 310S vs 310H vs 310 Pipe Fittings
All three grades share the 25Cr 20Ni base. Carbon is what separates them, and it decides how the fitting behaves once it is welded into a line.
| Point | SS 310 (S31000) | SS 310S (S31008) | 310H (S31009) |
|---|---|---|---|
| Carbon | 0.25% max | 0.08% max | 0.04 to 0.10% |
| Usual reason to choose | Older furnace specifications, cast and bar parts | Welded piping; the normal choice for fittings | Creep strength in pressure parts above about 550 °C, where the design code asks for an H grade |
| Weld zone sensitisation | Higher risk | Lower risk | Moderate |
| Dual certification | Fittings are often certified 310 / 310S when the heat meets both | Same | Not usually dual certified |
Where your drawings simply say "310", check the purchase specification. Most piping specifications for fittings in fact intend 310S.
SS 310 Pipe Fittings Specification
| Item | Detail |
|---|---|
| Forged Material Standard | ASTM A182 / ASME SA182 (F310, F310H) |
| Buttweld Material standard | ASTM A403 / ASME SA403 (WP310S, WP310H) |
| Buttweld Fitting Size | ½″ NB to 48″ NB (Seamless & Welded / Fabricated) |
| Forged Fitting Size | ¼″ to 4″ NB |
| Types | Seamless / Welded / Fabricated |
| Dimensional standards | ASME/ANSI B16.9, ASME B16.28, MSS-SP-43 |
| Wall schedules | Sch 5S, 10S, 40S, 80S, 160, XS, XXS, matched to the connecting pipe |
| Forged pressure class | Socket weld Class 3000, 6000, 9000; threaded Class 2000, 3000, 6000 |
| Bending Radius | R = 1D, 2D, 3D, 5D, 6D, 8D, 10D or custom |
| Forms | Elbow, Tee, Reducer, Cap, Stub End, Bend, Cross, Coupling |
| End Types | Bevelled Ends (BW) per ASME B16.25 / Plain End / Threaded |
| Heat treatment | Solution annealed 1040 °C min, rapid cooled |
| Surface finish | Pickled and passivated; bevel ends machined |
| Certification | EN 10204 3.1 or 3.2: confirmed at quotation |
Chemical Composition of SS 310 / 310S Pipe Fittings
| Element | 310 / S31000 | 310S / S31008 |
|---|---|---|
| Carbon (C) | 0.25 max | 0.08 max |
| Manganese (Mn) | 2.00 max | 2.00 max |
| Phosphorus (P) | 0.045 max | 0.045 max |
| Sulphur (S) | 0.030 max | 0.030 max |
| Silicon (Si) | 1.50 max | 1.00 max |
| Chromium (Cr) | 24.0 to 26.0 | 24.0 to 26.0 |
| Nickel (Ni) | 19.0 to 22.0 | 19.0 to 22.0 |
| Molybdenum (Mo) | 0.75 max | 0.75 max |
| Iron (Fe) | Balance | Balance |
Note: SS 310S (ASTM A403 WP310S) is the usual choice for welded piping because its carbon limit of 0.08% max is far below the 0.25% max allowed in 310. Less carbon means less chromium carbide forms during welding, which lowers the risk of sensitisation and intergranular corrosion.
Mechanical Properties of ASTM A403 WP310S and A182 F310 Fittings
| Property | ASTM A403 WP310S (buttweld) |
|---|---|
| Tensile strength, min | 515 MPa (75 ksi) |
| Yield strength 0.2% offset, min | 205 MPa (30 ksi) |
| Elongation in 50 mm, min | 28% longitudinal, 20% transverse |
| Hardness, max | 90 HRB / 192 HB |
| Solution annealing temperature | 1040 °C (1900 °F) min, then rapid cool |
Physical Properties of 310 Stainless Steel
| Property | Metric | Imperial |
|---|---|---|
| Density | 7.9 to 8.0 g/cm³ | 0.29 lb/in³ |
| Melting range | 1400 to 1450 °C | 2550 to 2640 °F |
| Modulus of elasticity | 200 GPa | 29 × 10⁶ psi |
| Mean coefficient of thermal expansion, 0 to 100 °C | 15.9 µm/m·°C | 8.8 µin/in·°F |
| Thermal conductivity at 100 °C | 14.2 W/m·K | 8.2 Btu/h·ft·°F |
| Electrical resistivity at 20 °C | 0.78 µΩ·m | 30.7 µΩ·in |
| Magnetic response, annealed | Non magnetic | Non magnetic |
Stainless Steel 310 Grade Pipe Fittings Equivalent Designations
| Grade | UNS | EN number | EN name | JIS | BS (withdrawn) |
|---|---|---|---|---|---|
| 310 | S31000 | 1.4841 | X15CrNiSi25-21 | SUH 310 | 310S24 |
| 310S | S31008 | 1.4845 | X8CrNi25-21 | SUS 310S | 310S16 / 310S31 |
Note: Equivalents are closest matches by composition. Check the purchase specification before substituting an EN or JIS grade for an ASTM grade.
Stainless Steel 310 Buttweld Fittings Size Chart: ASME B16.9 Dimensions
Dimensions in millimetres, inches in brackets.
| NPS | DN | OD at bevel, mm (in) | 90° LR elbow A | 45° elbow B | 90° SR elbow | Equal tee C | Reducer H | Cap E |
|---|---|---|---|---|---|---|---|---|
| ½ | 15 | 21.3 (0.840) | 38 (1.50) | 16 (0.62) | n/a | 25 (1.00) | n/a | 25 (1.00) |
| ¾ | 20 | 26.7 (1.050) | 38 (1.50) | 19 (0.75) | n/a | 29 (1.12) | 38 (1.50) | 25 (1.00) |
| 1 | 25 | 33.4 (1.315) | 38 (1.50) | 22 (0.88) | 25 (1.00) | 38 (1.50) | 51 (2.00) | 38 (1.50) |
| 1½ | 40 | 48.3 (1.900) | 57 (2.25) | 29 (1.12) | 38 (1.50) | 57 (2.25) | 64 (2.50) | 38 (1.50) |
| 2 | 50 | 60.3 (2.375) | 76 (3.00) | 35 (1.38) | 51 (2.00) | 64 (2.50) | 76 (3.00) | 38 (1.50) |
| 3 | 80 | 88.9 (3.500) | 114 (4.50) | 51 (2.00) | 76 (3.00) | 86 (3.38) | 89 (3.50) | 51 (2.00) |
| 4 | 100 | 114.3 (4.500) | 152 (6.00) | 64 (2.50) | 102 (4.00) | 105 (4.12) | 102 (4.00) | 64 (2.50) |
| 6 | 150 | 168.3 (6.625) | 229 (9.00) | 95 (3.75) | 152 (6.00) | 143 (5.62) | 140 (5.50) | 89 (3.50) |
| 8 | 200 | 219.1 (8.625) | 305 (12.00) | 127 (5.00) | 203 (8.00) | 178 (7.00) | 152 (6.00) | 102 (4.00) |
| 10 | 250 | 273.0 (10.75) | 381 (15.00) | 159 (6.25) | 254 (10.00) | 216 (8.50) | 178 (7.00) | 127 (5.00) |
| 12 | 300 | 323.8 (12.75) | 457 (18.00) | 190 (7.50) | 305 (12.00) | 254 (10.00) | 203 (8.00) | 152 (6.00) |
| 14 | 350 | 355.6 (14.00) | 533 (21.00) | 222 (8.75) | 356 (14.00) | 279 (11.00) | 330 (13.00) | 165 (6.50) |
| 16 | 400 | 406.4 (16.00) | 610 (24.00) | 254 (10.00) | 406 (16.00) | 305 (12.00) | 356 (14.00) | 178 (7.00) |
| 18 | 450 | 457 (18.00) | 686 (27.00) | 286 (11.25) | 457 (18.00) | 343 (13.50) | 381 (15.00) | 203 (8.00) |
| 20 | 500 | 508 (20.00) | 762 (30.00) | 318 (12.50) | 508 (20.00) | 381 (15.00) | 508 (20.00) | 229 (9.00) |
| 24 | 600 | 610 (24.00) | 914 (36.00) | 381 (15.00) | 610 (24.00) | 432 (17.00) | 508 (20.00) | 267 (10.50) |
A and B: centre to end of elbows. C: centre to end of tee run. H: end to end of reducer. E: cap length for standard wall; heavier walls have longer caps.
Wall Thickness by Schedule for SS 310 Grade Fittings (ASME B36.19M / B36.10M)
Fittings are ordered to match the wall of the connecting pipe. Millimetres, inches in brackets.
| NPS / DN | Sch 10S | Sch 40S | Sch 80S | Sch 160 | XXS |
|---|---|---|---|---|---|
| ½ / 15 | 2.11 (0.083) | 2.77 (0.109) | 3.73 (0.147) | 4.78 (0.188) | 7.47 (0.294) |
| ¾ / 20 | 2.11 (0.083) | 2.87 (0.113) | 3.91 (0.154) | 5.56 (0.219) | 7.82 (0.308) |
| 1 / 25 | 2.77 (0.109) | 3.38 (0.133) | 4.55 (0.179) | 6.35 (0.250) | 9.09 (0.358) |
| 1½ / 40 | 2.77 (0.109) | 3.68 (0.145) | 5.08 (0.200) | 7.14 (0.281) | 10.15 (0.400) |
| 2 / 50 | 2.77 (0.109) | 3.91 (0.154) | 5.54 (0.218) | 8.74 (0.344) | 11.07 (0.436) |
| 3 / 80 | 3.05 (0.120) | 5.49 (0.216) | 7.62 (0.300) | 11.13 (0.438) | 15.24 (0.600) |
| 4 / 100 | 3.05 (0.120) | 6.02 (0.237) | 8.56 (0.337) | 13.49 (0.531) | 17.12 (0.674) |
| 6 / 150 | 3.40 (0.134) | 7.11 (0.280) | 10.97 (0.432) | 18.26 (0.719) | 21.95 (0.864) |
| 8 / 200 | 3.76 (0.148) | 8.18 (0.322) | 12.70 (0.500) | 23.01 (0.906) | 22.23 (0.875) |
| 10 / 250 | 4.19 (0.165) | 9.27 (0.365) | 12.70 (0.500) | 28.58 (1.125) | 25.40 (1.000) |
| 12 / 300 | 4.57 (0.180) | 9.53 (0.375) | 12.70 (0.500) | 33.32 (1.312) | 25.40 (1.000) |
Sch 160 and XXS come from ASME B36.10M. For full schedule tables see our pipe schedule chart.
Applications of SS 310S Pipe Fittings
Grade 310 is chosen for oxidation and scaling resistance in hot gas, not for corrosion in wet process streams. The sectors below use it where line temperatures sit well above the range of 304 and 316.
| Sector | Typical 310 / 310S service |
|---|---|
| Refining | Fired heater auxiliaries, sulphur recovery unit hot gas lines, flare and incinerator connections |
| Petrochemicals | Furnace connections, hot air and flue gas ducting on cracking and reforming units |
| Gas processing and LNG | Incinerator and thermal oxidiser piping, hot regeneration gas lines |
| Power and water | Boiler auxiliaries, air preheater connections, flue gas handling |
| Fertiliser | Hot process gas lines around reformers and ammonia plant heaters |
| Chemical processing | High temperature reactor and kiln connections |
| Heat treatment and furnaces | Radiant tube connections, atmosphere gas lines, burner piping |
What Drives the Price of SS 310S Buttweld Fittings
We do not publish a fixed price for 310 fittings. Nickel and chromium prices move, and a 310 fitting holds roughly twice the nickel of a 304 fitting. These factors set the figure:
| Factor | Effect on price |
|---|---|
| Grade and heat | 310S, 310 and 310H differ; dual certified heats may cost more |
| Size and wall schedule | More metal per piece; Sch 80S and above raise weight sharply |
| WP-S, WP-W, WP-WX or WP-WU | Seamless costs more in large sizes; radiography or UT of welds adds cost |
| Fitting type and radius | 1D, 3D and 5D bends and special angles take extra work |
| Quantity | Larger lots per size lower the unit price |
| Stock or mill order | Uncommon sizes need a production run |
| Certificate level | EN 10204 3.2 needs a third party witness |
| Third party inspection and testing | Witness, PMI and hardness checks are charged per lot |
| Incoterm and destination port | Freight and insurance are included only under C and D terms |
Send these for a fast quotation: grade (310, 310S or 310H), standard (A403 or A182), fitting type, NPS or DN, wall schedule or pressure class, construction (WP-S, WP-W, WP-WX), quantity per item, end finish, certificate level (3.1 or 3.2), inspection agency if required, destination port and required date.
Types of 310 Stainless Steel Buttweld Fittings and Forged Fittings
Every fitting below is made in 310S as standard, with 310 and 310H on request. Buttweld fittings follow ASME B16.9 and B16.28; forged fittings follow ASME B16.11.
Request a Quote for Stainless Steel 310 Pipe Fittings
Send your line list or material take off with grades, sizes, schedules and quantities. Add the certificate level, any inspection or sour service requirement, your Incoterm and the destination port. A complete enquiry gets a complete quotation on the first reply.
Request a QuotationComplete the Line: Pipe, Fitting and Flange in Grade 310S
| Product | Standard | Page |
|---|---|---|
| SS 310S pipe | ASTM A312 / A358 | SS 310S pipe |
| SS 310S seamless pipe | ASTM A312 | SS 310S seamless pipes |
| SS 310S welded pipe | ASTM A312 | SS 310S welded pipes |
| SS 310H pipe | ASTM A312 | SS 310H pipe |
| SS 310 flanges | ASTM A182 F310, ASME B16.5 | SS 310 flanges |
| Stainless steel pipe fittings | ASTM A403 | Stainless steel pipe fittings |
Buyer Questions on SS 310S Fittings for GCC and Export Orders
Only within narrow limits, and it is seldom the right choice. ISO 15156-3 accepts austenitic stainless steels of this type solution annealed at 22 HRC maximum, inside limits on temperature, chlorides and H2S partial pressure. Grade 310 is chosen for high temperature oxidation, so for wet sour service your material selection report will normally name another alloy.
Carbon. SS 310 allows up to 0.25% carbon and SS 310S up to 0.08%. The lower carbon reduces carbide formation next to welds, which is why 310S is the usual grade for welded piping. Fittings are often dual certified 310 / 310S when the heat meets both.
Buttweld fittings follow ASTM A403 for material and ASME B16.9 for dimensions. Forged socket weld and threaded fittings follow ASTM A182 for material and ASME B16.11 for dimensions and pressure class.
Certificate level and inspection arrangements are confirmed at quotation. State 3.1 or 3.2 and the agency you require in your enquiry.
Currency and Incoterm are confirmed on each quotation. Tell us your preferred terms and destination port when you enquire.
Grade, standard, fitting type, NPS or DN, schedule or class, construction, quantity, end finish, certificate level, inspection requirement, destination port and required date. A line list or material take off works just as well.
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