Fasteners · MSS SP-58 / manufacturer standard
U-bolt — MSS SP-58 / manufacturer standard
U-bolt — a U-shaped bolt for clamping pipes to supports. U-bolts hold pipes to supports and structures. Sized by pipe NPS with a threaded length on each leg.
- MSS SP-58 / manufacturer standard
- 18 grades
- EN 10204 3.1 / 3.2
Reviewed by the Kanak Steel & Engineering Co. technical team · Updated October 2026
What is an u-bolt?
Short answer
An u-bolt is a U-shaped bolt for clamping pipes to supports. U-bolts hold pipes to supports and structures. Sized by pipe NPS with a threaded length on each leg.
U-bolt: What to Know Before Ordering
- Sized to pipe NPS
- With nuts and plates
- Matching or isolated material
U-bolt Materials & Grades
| Grade | Material standard | Best for |
|---|---|---|
| Inconel 825 u-bolt | Finished fastener specification not asserted; material/feedstock may be supplied to ASTM B425 (UNS N08825), where applicable; manufacturing route and finished fastener requirements are to the purchase specification or project drawing | Sulphuric and phosphoric acid service, chloride stress-corrosion cracking and sour gas |
| SS 904L u-bolt | Finished fastener specification not asserted; material/feedstock may be supplied to ASTM A479 (UNS N08904), where applicable; manufacturing route and finished fastener requirements are to the purchase specification or project drawing | Dilute sulphuric acid, phosphoric acid and chloride-bearing cooling water |
| SS 304 u-bolt | Finished fastener specification not asserted; UNS S30400 material — requirements to the purchase specification or project drawing | General corrosion resistance, food, water and architectural work |
| SS 304L u-bolt | Finished fastener specification not asserted; UNS S30403 material — requirements to the purchase specification or project drawing | Welded tanks, piping and vessels in general corrosive service |
| SS 310 / 310S u-bolt | Finished fastener specification not asserted; material/feedstock may be supplied to ASTM A276 / A479 (UNS S31008), where applicable; manufacturing route and finished fastener requirements are to the purchase specification or project drawing | Furnaces, burners and heat treatment at high temperature |
| SS 316 / 316L u-bolt | Finished fastener specification not asserted; UNS S31603 material — requirements to the purchase specification or project drawing | Chloride-bearing process fluids, marine air and pharmaceutical service |
| SS 321 u-bolt | Finished fastener specification not asserted; UNS S32100 material — requirements to the purchase specification or project drawing | High-temperature service between 425 and 815 °C |
| SS 347 u-bolt | Finished fastener specification not asserted; UNS S34700 material — requirements to the purchase specification or project drawing | Welded high-temperature piping in refineries and power plants |
| Duplex 2205 u-bolt | Finished fastener specification not asserted; material/feedstock may be supplied to ASTM A276 / A479 (UNS S32205), where applicable; manufacturing route and finished fastener requirements are to the purchase specification or project drawing | Strength with chloride resistance at a stainless-steel budget |
| Super Duplex 2507 u-bolt | Finished fastener specification not asserted; material/feedstock may be supplied to ASTM A276 / A479 (UNS S32750), where applicable; manufacturing route and finished fastener requirements are to the purchase specification or project drawing | Seawater and high-chloride service where strength also matters |
| Inconel 600 u-bolt | Finished fastener specification not asserted; material/feedstock may be supplied to ASTM B166 (UNS N06600), where applicable; manufacturing route and finished fastener requirements are to the purchase specification or project drawing | High-temperature oxidation, caustic and nuclear service |
| Inconel 625 u-bolt | Finished fastener specification not asserted; material/feedstock may be supplied to ASTM B446 (UNS N06625), where applicable; manufacturing route and finished fastener requirements are to the purchase specification or project drawing | Seawater, high strength and high temperature in one alloy |
| Inconel 718 u-bolt | Finished fastener specification not asserted; material/feedstock may be supplied to ASTM B637 (UNS N07718), where applicable; manufacturing route and finished fastener requirements are to the purchase specification or project drawing | Very high strength at temperatures up to about 650 °C |
| Incoloy 800 / 800H / 800HT u-bolt | Finished fastener specification not asserted; material/feedstock may be supplied to ASTM B408 (UNS N08800), where applicable; manufacturing route and finished fastener requirements are to the purchase specification or project drawing | Furnaces, petrochemical heaters and high-temperature piping |
| Hastelloy C276 u-bolt | Finished fastener specification not asserted; material/feedstock may be supplied to ASTM B574 (UNS N10276), where applicable; manufacturing route and finished fastener requirements are to the purchase specification or project drawing | The most aggressive mixed acids, wet chlorine and hypochlorite |
| Hastelloy C22 u-bolt | Finished fastener specification not asserted; material/feedstock may be supplied to ASTM B574 (UNS N06022), where applicable; manufacturing route and finished fastener requirements are to the purchase specification or project drawing | Mixed oxidising and reducing acids, and weld overlays |
| Monel 400 u-bolt | Finished fastener specification not asserted; material/feedstock may be supplied to ASTM B164 (UNS N04400), where applicable; manufacturing route and finished fastener requirements are to the purchase specification or project drawing | Seawater, hydrofluoric acid and marine service |
| Monel K500 u-bolt | Finished fastener specification not asserted; material/feedstock may be supplied to ASTM B865 (UNS N05500), where applicable; manufacturing route and finished fastener requirements are to the purchase specification or project drawing | High-strength pump shafts, bolting and springs in seawater |
Other fasteners
Stud boltA fully threaded rod supplied with two heavy hex nuts.Hex boltA bolt with a hexagonal head.Heavy hex nutA thicker and wider hexagon nut for pressure bolting.Hex nutA standard hexagon nut.WasherA flat or spring ring that spreads bolt load.Threaded rodA continuously threaded bar cut to length.Eye boltA bolt with a loop head for lifting or anchoring.Anchor boltA bolt that fixes structures or equipment to concrete.Foundation boltA heavy bolt set in concrete for machinery bases.Socket head cap screwA screw with a cylindrical head and hexagon socket.Machine screwA small-diameter screw for equipment assembly.
U-bolt — questions buyers ask
What is an u-bolt?
An u-bolt is a U-shaped bolt for clamping pipes to supports. U-bolts hold pipes to supports and structures. Sized by pipe NPS with a threaded length on each leg.
Should U-bolts match the pipe material?
Use the same alloy, or an isolating sleeve, to avoid galvanic corrosion between pipe and bolt.
Which grades are u-bolts available in?
Inconel 825, SS 904L, SS 304, SS 304L, SS 310 / 310S, SS 316 / 316L, SS 321, SS 347, Duplex 2205, Super Duplex 2507, Inconel 600, Inconel 625, Inconel 718, Incoloy 800 / 800H / 800HT, Hastelloy C276, Hastelloy C22, Monel 400, Monel K500.
Which standard covers u-bolt dimensions?
MSS SP-58 / manufacturer standard. The material standard depends on the grade.
Reviewed by the technical team, Kanak Steel & Engineering Co.
Sources: the ASTM / ASME specifications named on this page and producer datasheets · Last updated October 2026
Sources: the ASTM / ASME specifications named on this page and producer datasheets · Last updated October 2026
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