SS 321 U-boltASTM A193 · MSS SP-58 / manufacturer standard · Manufacturer, stockist & exporter, India
AISI 321 · UNS S32100
An SS 321 u-bolt is a U-shaped bolt for clamping pipes to supports, made from SS 321 to ASTM A193 B8T. U-bolts hold pipes to supports and structures. Sized by pipe NPS with a threaded length on each leg.
- ASTM A193
- MSS SP-58 / manufacturer standard
- EN 10204 3.1 / 3.2
- Export packing
Reviewed by the Kanak Steel & Engineering Co. technical team · Updated October 2026
What is an SS 321 U-bolt?
- What it is
- A U-shaped bolt for clamping pipes to supports
- Material
- ASTM A193 B8T
- Dimensions
- MSS SP-58 / manufacturer standard
- Grade
- SS 321 · UNS S32100
- Best at
- High-temperature service between 425 and 815 °C
SS 321 U-bolt Specification
| Product | SS 321 U-bolt |
|---|---|
| Material standard | ASTM A193 B8T |
| Dimensional standard | MSS SP-58 / manufacturer standard |
| Sizes | M10 – M64 · ½" – 4" (others on request) |
| Threads | UNC · UN-8 · metric coarse |
| Testing | PMI · dimensional · NDT and IGC on request |
| Documents | EN 10204 3.1 · 3.2 with third-party inspection |
When to Choose an U-bolt
U-bolts hold pipes to supports and structures. Sized by pipe NPS with a threaded length on each leg.
- Sized to pipe NPS
- With nuts and plates
- Matching or isolated material
More on choosing: U-bolt guide.
SS 321 U-bolt: Why 321 for u-bolts
U-bolts hold pipes to supports and structures. Sized by pipe NPS with a threaded length on each leg. In SS 321, 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 fasteners resist atmospheric and process corrosion. SS 321 is picked for high-temperature service between 425 and 815 °C. |
|---|---|
| Typical service | Aircraft exhaust — Manifolds, bellows and exhaust systems. |
| Bolting | ASTM A193 B8T studs with A194 8T nuts |
SS 321 U-bolt Chemical Composition
| Element | Weight % |
|---|---|
| Chromium | 17.0 – 19.0 |
| Nickel | 9.0 – 12.0 |
| Titanium | 5 × (C + N) min, 0.70 max |
| Carbon | 0.08 max |
| Manganese | 2.00 max |
| Silicon | 0.75 max |
| Nitrogen | 0.10 max |
| Phosphorus | 0.045 max |
SS 321 U-bolt Mechanical Properties
| Annealed plate & sheet | Value |
|---|---|
| Tensile strength | 515 MPa · 75 ksi |
| Yield strength 0.2% | 205 MPa · 30 ksi |
| Elongation | 40% |
| Hardness | 217 HB max |
Full chemistry, properties and equivalents are on the SS 321 grade page.
Other SS 321 fasteners
SS 321 U-bolts for export
FOB / CIF · Nhava Sheva (JNPT), MumbaiSS 321 U-bolt — questions buyers ask
Should U-bolts match the pipe material?
Use the same alloy, or an isolating sleeve, to avoid galvanic corrosion between pipe and bolt.
What nut is used with SS 321 u-bolts?
ASTM A194 8T heavy hex nuts.
Which standard covers SS 321 u-bolts?
The material is ASTM A193 B8T; dimensions follow MSS SP-58 / manufacturer standard. Always state both on your purchase order, with the edition if your project specifies one.
What decides the price of a SS 321 u-bolt?
The alloy price, the size and dimensions, 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 mill certificates as standard, 3.2 with third-party inspection on request, plus dimensional and PMI reports.
Sources: the ASTM / ASME specifications named on this page and producer datasheets · Last updated October 2026