SS 310 / 310S UnionASTM A182 · MSS SP-83 · Manufacturer, trader & exporter, India
AISI 310S · UNS S31008
An SS 310 / 310S union is a three-piece forged fitting that joins pipes and can be taken apart, made from SS 310 / 310S to ASTM A182 F310. Unions let a small-bore line be disconnected for maintenance without cutting. Made to MSS SP-83 in threaded or socket-weld ends.
- ASTM A182
- MSS SP-83
- EN 10204 3.1 / 3.2
- Export packing
Reviewed by the Kanak Steel & Engineering Co. technical team · Updated October 2026
What is an SS 310 / 310S Union?
- What it is
- A three-piece forged fitting that joins pipes and can be taken apart
- Material
- ASTM A182 F310
- Dimensions
- MSS SP-83
- Grade
- SS 310 / 310S · UNS S31008
- Best at
- Furnaces, burners and heat treatment at high temperature
SS 310 / 310S Union Specification
| Product | SS 310 / 310S Union |
|---|---|
| Material standard | ASTM A182 F310 |
| Dimensional standard | MSS SP-83 |
| Sizes | ⅛" – 4" (ASME B16.11) |
| Wall / class | Class 2000 / 3000 / 6000 / 9000 |
| Ends | Socket weld · NPT threaded |
| Testing | PMI (as specified in the PO) · dimensional · NDT and IGC on request |
| Documents | EN 10204 3.1 or 3.2 on request / as specified in the PO |
When to Choose an Union
Unions let a small-bore line be disconnected for maintenance without cutting. Made to MSS SP-83 in threaded or socket-weld ends.
- Three pieces: nut, male and female ends
- Threaded or socket weld
- Class 3000 / 6000
More on choosing: Union guide.
SS 310 / 310S Union: Why 310S for unions
Unions let a small-bore line be disconnected for maintenance without cutting. Made to MSS SP-83 in threaded or socket-weld ends. In SS 310 / 310S, the choice usually comes down to the medium and temperature — the rows here are the points buyers check for this exact combination.
| Why this grade | Stainless fittings keep the line clean and corrosion-free. SS 310 / 310S is picked for furnaces, burners and heat treatment at high temperature. |
|---|---|
| Typical service | Furnace parts — Muffles, retorts, radiant tubes and conveyor belts. |
| Welding to carbon steel | ER309L (or E309L electrode) is the usual filler when joining it to carbon steel |
| Matching filler | ER310 (AWS A5.9) |
SS 310 / 310S Union Chemical Composition
Under technical review for TDS.
| Element | Current requirement |
|---|---|
| Chromium | As specified |
| Nickel | As specified |
| Carbon | As specified |
| Manganese | As specified |
| Silicon | As specified |
| Phosphorus | As specified |
| Sulphur | As specified |
| Iron | As specified |
Numerical specification requirements are published only after the applicable current standard edition has been verified. Governing specification to be verified: ASTM A240 for UNS S31008.
SS 310 / 310S Union Mechanical Properties
Under technical review for TDS.
| Property | Current requirement |
|---|---|
| Tensile strength | As specified |
| Yield strength 0.2% | As specified |
| Elongation | As specified |
| Hardness | As specified |
Numerical specification requirements are published only after the applicable current standard edition has been verified. Governing specification and condition to be verified: ASTM A240 for UNS S31008 — Annealed plate & sheet.
Full chemistry, properties and equivalents are on the SS 310 / 310S grade page.
Other SS 310 / 310S pipe fittings
SS 310 / 310S Union — questions buyers ask
Can unions be used in high-pressure lines?
Class 3000 and 6000 unions are rated for high pressure on small bores, but many codes limit their use in hazardous service.
Can SS 310 / 310S unions be welded to carbon steel?
Yes — ER309L (or E309L electrode) is the usual filler when joining it to carbon steel.
Which standard covers SS 310 / 310S unions?
The material is ASTM A182 F310; dimensions follow MSS SP-83. Always state both on your purchase order, with the edition if your project specifies one.
What decides the price of a SS 310 / 310S union?
The alloy price, the size and schedule or class, quantity, and the testing and documents required. Send your list and we quote the same working day.
What documents do you supply?
EN 10204 3.1 or 3.2 certificates available on request / as specified in the PO; dimensional reports as required. PMI can be arranged depending on product and requirements, as specified in the PO.
Sources: the ASTM / ASME specifications named on this page and producer datasheets · Last updated October 2026