Buy U-Bolts Online in Australia
U-Bolt Selection — Quick Reference
U-bolts secure pipes, cables, structural members, suspended equipment around bars + tubes that don't accept conventional bolting. Selection turns on bend type (round bend / square bend / J-bolt), inside dimension (matches held component), thread length, and material (galv vs SS).
| U-Bolt Type | Best For | Common Material |
|---|---|---|
| Round Bend (Round Bar) | Pipe + round bar mounting — standard plumbing + structural | Galv / Zinc / 304 SS / 316 SS |
| Square Bend (Square Bar) | RHS + SHS tube + square sections | Galv / Zinc / 304 SS / 316 SS |
| J-Bolt (Half-U) | Anchoring to wall + single-side fixing | Galv / Zinc |
| Threaded Both Ends with Mounting Plate | Complete kit — bolt + plate + nuts | Galv / SS — pre-matched components |
| Vehicle Suspension U-Bolt (Grade 8) | Leaf spring to axle — vehicle + trailer suspension | Heat-treated alloy steel |
| Marine U-Bolt (316 Stainless) | Boat + marine fittings — chloride exposure | 316 stainless steel |
| Heavy-Duty Threaded (M16+) | Heavy structural — large pipe + structural sections | Galv / hot-dip galv for outdoor |
Sizing rule: Inside dimension must match the OD of the component being held (round bar nominal + 1-2mm clearance for pipe). Thread length determines clamping range against mounting plate thickness. Material: zinc/galv for indoor + dry; hot-dip galv for outdoor + light corrosion; 304 SS for general corrosion; 316 SS for marine + chemical + chloride. Vehicle U-bolts: ALWAYS replace as a set (not single) + retorque after first 100km — leaf spring beds in + bolts can loosen. Companion: all fasteners, bolts, eye bolts, anchors.
U-Bolts for Australian Pipe Mounting, Suspension and Structural Fastening
U-bolts are the U-shaped threaded fasteners used to secure pipes, cables, structural members, and suspended equipment around bars, tubes, and other components that don't accept conventional bolted fastening. The U-shape passes around the held component, with both threaded ends extending through a mounting plate where nuts secure the assembly. For Australian plumbing, vehicle suspension, structural, and industrial mounting applications, U-bolts are essential. AIMS Industrial supplies U-bolts in metric and imperial sizes across the materials and bend types Australian customers use.
The U-bolt types we stock
- Round-bend U-bolts — semicircular bend; for round pipe and tube mounting
- Square-bend U-bolts — rectangular bend; for square section, channels, and rectangular tubes
- Long-shank U-bolts — extended threaded shanks for thicker mounting plates
- Heavy-duty U-bolts — larger diameter for higher-load applications
- U-bolt assemblies — pre-matched U-bolt with mounting plate and nuts
Materials and finishes
- Galvanised steel — the standard for outdoor and corrosive environments
- Zinc-plated steel — for indoor and protected applications
- Stainless steel 304 and 316 — for marine, food-grade, and aggressive corrosive applications
- Black self-colour steel — for paintable applications and indoor structural use
Where U-bolts earn their place
- Pipe mounting — securing pipework to walls, ceilings, and structural members
- Vehicle suspension — leaf spring U-bolts secure axles to springs in trucks, trailers, agricultural equipment
- Cable and conduit support — large-diameter cable and conduit fastening
- Equipment suspension — hanging tanks, machinery, and equipment from structural members
- Marine and outdoor applications — stainless U-bolts in saltwater and corrosive environments
- Antenna and signage mounting — securing antennas and signs to poles
- Custom fabrication — wherever a wraparound fastening is needed
Sizing — match to the component being held
U-bolt sizing has two main dimensions: the thread diameter (the threaded shank size) and the inside dimension (the diameter of pipe or width of section the U-bolt fits around). Common metric thread sizes range from M6 through M30; inside dimensions range from 12mm through 200mm depending on application. Match both dimensions — undersized inside dimension can't fit around the component; oversized leaves the component loose in the U-bolt.
Working load capacity
U-bolt working load capacity depends on the thread size, material grade, and mounting plate stiffness. For structural applications, U-bolts are typically rated as a system (U-bolt plus mounting plate plus nuts) rather than as individual components. Manufacturer data sheets give the working load for specific configurations. For lifting applications, U-bolts must be rated lifting components and supplied with traceable documentation — generic structural U-bolts aren't rated for lifting use.
Vehicle suspension U-bolts
Leaf spring U-bolts for trucks, trailers, and agricultural equipment are typically supplied as matched assemblies with the bolt, top plate, and nuts pre-matched for the spring stack thickness. Re-torquing is standard practice for new installations — torque after first 100km of operation, then periodically to maintain the specified preload. Loose U-bolts on vehicle suspension cause spring shift and serious safety issues.
Brands stocked at AIMS
Hobson and Bremick cover the U-bolt range across the standard sizes, materials, and finishes. For specialty U-bolts (large dimensions, specific OEM patterns, vehicle-specific assemblies), sourcing through our distribution channels covers most options.
Companion ranges at AIMS
U-bolts sit alongside our broader fastener range — see turnbuckles, rope grips, cable and conduit saddles, and structural bolt assemblies for the related products.
Need help speccing U-bolts for pipe mounting, vehicle suspension, or structural application? contact our team — we'll match by thread size, inside dimension, and material.
People Also Ask — U-Bolts
Q: What's a U-bolt used for?
U-bolts clamp around pipes, shafts, or structural members — providing a strong mechanical clamp without welding or drilling through the clamped object. Common in plumbing (pipe support), automotive (leaf spring to axle), structural engineering (cable and conduit support), and general workshop fixturing. The U-shape grips the round or rectangular object, with the legs threaded for nuts to provide clamping force.
Q: How do I size a U-bolt for my application?
Three dimensions matter: inside diameter (clears the object being clamped), thread size (matches the nuts), and leg length (long enough to pass through the mounting plate plus nut engagement). Standard U-bolts come in inch and metric sizes — match the inside dimension to the object's diameter or width. Specify exact dimensions when ordering; standard catalogues list common sizes but custom sizes can be made.
Q: What material U-bolt suits outdoor use?
304 stainless steel for general outdoor and corrosive environments. 316 stainless for marine and coastal. Hot-dip galvanised carbon steel for general outdoor at lower cost than stainless. Bare steel rusts quickly outdoors — only use indoors or in dry environments. Match the U-bolt material to the surrounding structure to avoid galvanic corrosion at the contact points.
Q: Round bend or square bend U-bolt?
Round-bend U-bolts have a semicircular bend — used to clamp round pipe or shaft. Square-bend U-bolts have a rectangular bend with flat sides and 90-degree corners — used to clamp square or rectangular section. Using a round-bend U-bolt on square section creates point loads at the corners; using a square-bend on a round section creates point loads at the sides. Match the bend type to the object profile.
Q: How tight should U-bolt nuts be torqued?
Depends on the application — automotive U-bolts (leaf spring) have specific torque specs from the vehicle manufacturer (typically 80-150 Nm for common sizes). Structural U-bolts: torque to the nut/bolt grade specification adjusted for the application's clamp force requirement. For pipe clamps, hand-tight plus a quarter to half turn is usually enough — over-tightening crushes the pipe.