Furnace components in 25% chromium steel often give trouble at shutdown rather than at temperature, because long exposure in the intermediate range forms sigma phase that leaves the metal brittle once it cools to ambient. The damage shows up when the plant is cold. Chromium and nickel carry the load in between. The stainless steel pipes and tubes of grade 310 310S have about 25% chromium 20% nickel and they are proved to be better than 304 and 316 grades when it comes to scaling and cyclic heating. This property makes them suitable for lining of furnaces flues and other heating equipment used in Oman and other regions. Other grades are on the stainless steel pipes and tubes hub.
Where 310 and 310S Are Used
- Furnace tubes, radiant tubes and flue components
- Heat treatment equipment, muffles and retorts
- Kiln and incinerator internals
- High-temperature ducting and expansion joints
- Cryogenic service, where the austenitic structure stays tough
For stabilised high-temperature service with welding, 321 and 347 are alternatives. For sulphur-bearing hot gas, 446 is often preferred.
Sigma Phase: Why 310 Fails Cold
| Stage | What happens |
|---|---|
| Service at high temperature | The alloy performs well, resisting oxidation and scaling |
| Long holds in the intermediate range | A brittle chromium-rich sigma phase precipitates at grain boundaries |
| Cooling to ambient | The sigma-embrittled metal has little toughness left, and handling or thermal shock can crack it |
| Solution annealing | Re-annealing dissolves sigma phase and restores ductility, where the component can be treated |
Two practical consequences follow. First, inspect and handle long-serving 310 components carefully during outages, since a part that looks sound can fracture when disturbed cold. Second, avoid unnecessary time in the sigma-forming range during heat-up and cool-down where the process allows.
310 or 310S? 310S has lower carbon, which improves weldability and reduces carbide precipitation. 310H has higher, controlled carbon for creep strength where a code case requires it.
310S Corrosion and Service Limits
310S resists high-temperature oxidation and scaling, but it is not a chloride-resistant grade: its molybdenum-free chemistry leaves it open to pitting and chloride stress corrosion cracking in warm chloride service. In sulphur-bearing hot gas, the high nickel content can form low-melting sulphides, so ferritic grades are sometimes preferred. Under NACE MR0175 / ISO 15156-3, austenitic grades are acceptable only within defined limits. State your service conditions in the RFQ; requirements are confirmed at quotation.
What Affects the Price of 310/310S
- Alloy surcharges, which move with nickel, molybdenum and chromium markets
- Seamless or welded
- Size, schedule or wall, and length
- Surface finish and any polishing
- Testing, including corrosion testing and PMI
- Quantity and stock availability versus a mill order
- Certification (EN 10204 3.1 or 3.2) and third-party inspection
- Incoterm and destination port
Quotations are available in USD, OMR, AED, SAR, QAR, KWD and BHD, on EXW, FOB, CFR or CIF terms.
What to send for a quotation:
grade, standard, seamless or welded, NPS or OD, schedule or wall, length, quantity, finish, testing, certification, inspection, destination port and required date.
310/310S Certificates and Inspection
310/310S is supplied with EN 10204 3.1 certificates as standard, and EN 10204 3.2 certificates on request. Inspection by the buyer's nominated third-party agency can be arranged; state your requirement in the RFQ. Check the chemistry, the heat treatment condition, tensile results and any corrosion test report. PMI on receipt confirms the grade. See the MTC and EN 10204 certification guide.
Packing and Site Storage
Lead time is confirmed at quotation. Material ships with end caps and, where specified, protective wrapping. Keep it away from carbon steel racks, slings and grinding dust, since embedded iron rusts on the surface and can start pitting. On coastal Gulf sites, rinse salt deposits off before fabrication.
Fittings and Related Grades
Match with ASTM A403 WP310S fittings and ASTM A182 F310 flanges.
- stainless steel fittings and flanges hub
- Stainless steel 321 pipes and tubes
- 253MA pipes and tubes for high-temperature service with better strength
310S is used in refinery and petrochemical, power generation and fertilizer plants.
SS 310 and 310S FAQ
What is the difference between 310 and 310S?
310S has lower carbon, which improves weldability and reduces carbide precipitation. 310H has controlled higher carbon for creep strength.
What temperature can 310S handle?
It is used well above the range of 304 and 316 for oxidation resistance. The exact limit comes from the design code and the atmosphere involved.
What is sigma phase embrittlement?
A brittle chromium-rich phase that forms after long exposure at intermediate temperatures, leaving the steel with little toughness once cooled.
Is 310S suitable for chloride service?
No. It has no molybdenum and pits in chloride environments. Use 316L, 904L, 254 SMO or duplex instead.
What is the EN equivalent of 310S?
1.4845 (X8CrNi25-21).
What should I send for a quotation?
Send the grade, standard, form, size, wall, length, quantity, finish, testing, certification, inspection and destination port.
Request a Quote for Stainless Steel 310/310S Pipes and Tubes
Send the grade, size, wall and quantity, with the furnace or piping specification attached. Every enquiry is checked against the governing standard before the offer is prepared, so service temperature and atmosphere are considered before material is selected.