Precision-formed round bend U-bolts for pipe clamping, available in 304/316 stainless steel, carbon steel and A320 L7, with rolled threads and standard hex nuts.
Round U bolts are the most widely used pipe clamping fastener in construction, marine, oil & gas and HVAC applications. Our round bend U-bolts are manufactured to BS 3974 Part 1 and DIN 3570 Type A standards, covering nominal pipe sizes from NB 8 to NB 600 (pipe OD 13.7 mm – 610 mm) with thread sizes from M6 to M24. Choose from gripped (anchor) U-bolts that hold the pipe firmly in all directions, or non-gripped (guide) U-bolts that allow longitudinal thermal movement. Materials include carbon steel with hot-dip galvanised, zinc plated or self-colour finishes, plus 304 and 316 stainless steel for corrosive environments, and A320 L7 for low-temperature service. All U-bolts are supplied with hex nuts as standard, with rubber lined and anti-vibration options available on request.
| Nominal Pipe Size | Pipe OD (mm) | Thread | A – Inside Width (mm) | D – Thread Length (mm) | E – Leg Centre (mm) |
|---|---|---|---|---|---|
| NB15 | 21.3 | M8 | 22 | 25 | 35 |
| NB20 | 26.9 | M8 | 27 | 25 | 42 |
| NB25 | 33.7 | M8 | 37 | 25 | 44 |
| NB40 | 48.3 | M10 | 50 | 35 | 60 |
| NB50 | 60.3 | M10 | 65 | 35 | 64 |
| NB80 | 88.9 | M16 | 89 | 50 | 98 |
| NB100 | 114.3 | M16 | 119 | 50 | 108 |
| NB150 | 168.3 | M20 | 170 | 55 | 140 |
| NB200 | 219.1 | M20 | 225 | 65 | 174 |
| NB300 | 323.9 | M20 | 330 | 65 | 225 |
Full size range NB 8 – NB 600 available. Custom sizes, extended legs and rubber lined versions on request.
🔩 304 Stainless Steel
General corrosion resistance, indoor and outdoor use
⚓ 316 Stainless Steel
Marine-grade, chloride and chemical resistant
🛡️ Carbon Steel + Hot-Dip Galvanised
Heavy-duty outdoor protection
⚙️ Carbon Steel + Zinc Plated
Cost-effective indoor corrosion protection
❄️ A320 L7
Low-temperature alloy steel for cryogenic service
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| Thread Length | measure the threaded portion from the bottom of the leg upward |
|---|---|
| Rod Diameter | measure rod thickness with caliper |
| Inside Length | measure from inside of the curve to the tip of the legs |
| Inside Width | measure between the inner edges of the two legs |
Gripped (anchor) U-bolts have a tight radius matching the pipe OD to lock the pipe in all directions. Non-gripped (guide) U-bolts have a slightly larger radius, allowing axial movement for thermal expansion.
For general outdoor use choose hot-dip galvanised carbon steel; for coastal or chemical environments choose 316 stainless steel.
Standard threads range from M6 to M24, matching nominal pipe sizes NB 8 to NB 600.
Yes. Custom inside widths, leg lengths, thread lengths and materials are available — send us your drawing or dimensions.
Looking for square bend U-bolts for square or rectangular hollow sections? Browse our Square U Bolts collection →
Send us your pipe size, material and quantity — we reply within 24 hours.