What are U-bolts?
U-bolts are U-shaped fasteners with two threaded legs and a curved crown used to clamp, support, or anchor round or irregular shapes. Paired with nuts and washers, U-bolts secure pipes, tubes, conduit, cables, and machinery to beams, channel, or slabs and are common in construction, plumbing, marine, and automotive work.
Why choose U-bolts?
- Secure clamping — the U-shape conforms to pipes and round stock for a strong, even hold.
- Versatile mounting — attach to wood, steel, concrete (with anchors), or strut/channel systems.
- Easy service — removable nuts make inspection and replacement straightforward.
- Corrosion-ready options — available in hot-dip galvanized and stainless for outdoor and marine use.
Types and styles of U-bolts
- Round U-bolts — crown radius matches pipe or tube OD for maximum contact.
- Square U-bolts — shaped for mounting to flat channel, angle, or rectangular tube.
- Semi-round or pipe-size U-bolts — sized to standard pipe ODs for mechanical trades.
- U-bolt beam clamps / saddle kits — include saddles/plates to spread load and protect the pipe.
Materials and coatings for U-bolts
- Carbon steel, zinc-plated — economical indoor protection.
- Hot-dip galvanized steel — thick zinc coating for long-term outdoor durability.
- Stainless steel 304 — broad corrosion resistance for most environments.
- Stainless steel 316 — superior resistance for coastal/marine and chloride exposure.
Common applications for U-bolts
- Supporting and guiding pipes and conduit on walls, beams, and strut
- Exhausts, suspensions, brake lines, and accessories in automotive and heavy equipment
- Marine and outdoor hardware where corrosion resistance is critical
- Securing tubes, cables, poles, and machinery to structures or foundations
How do I size and specify U-bolts?
Specify by rod diameter (bolt size), inside width (clear distance between legs), inside height (from crown to bearing surface), thread length, and material/finish. For pipe runs, match the U-bolt’s inside width or radius to the pipe’s outside diameter and include a saddle/plate if you need extra load spread or surface protection.
Installation tips for U-bolts
- Use flat washers and a saddle/plate to distribute load and protect the pipe or cable jacket.
- Tighten evenly on both legs to keep the load centered; avoid over-compressing soft insulation or hose.
- For vibration, add lock washers, nylon-insert nuts, or threadlocker per service conditions.
- In corrosive settings, keep hardware metals matched to reduce galvanic corrosion.