U-Bolts

Verified by Mel Sykes, Industrial Supply Chain Specialist - April 2026

Specification	Details
Types	Round bend, square bend, semi-round
Materials	Mild steel zinc plated, A2 stainless, A4 stainless, HDG
Pipe sizes	M6 x 15mm NB to M20 x 250mm NB
Standards	BS 3974 (pipe supports)
Applications	Pipe clamps, exhaust hangers, leaf spring mounts

What are U-Bolts?

U-Bolts are mechanical fasteners consisting of a U-shaped piece of metal with two straight legs that bend back and overlap to form a bolt hole. They're commonly used for securing pipes, hoses, and cables in place.

Types and Variants

U-Bolts come in various types based on their shape:

• Round Bend: These have rounded corners between the U-shape and the straight part of the legs.
• Example: M10 x 50mm round bend, suitable for pipe clamps up to 20mm diameter.
• Square Bend: The transition from the U-shape to the straight leg is sharp and square.
• Example: M8 x 30mm square bend, used in leaf spring mounts with a load rating of 15kN.
• Semi-Round (or Semi-Circular): This type has slightly rounded corners but not as pronounced as round bend.
• Example: M6 x 20mm semi-round, ideal for exhaust hangers with a temperature range up to 450°C.

Materials and Specifications

U-Bolts are made from different materials each with its own advantages:

• Mild Steel Zinc Plated (EN10248): Economical option with corrosion resistance.
• Example: EN10248 grade M6 x 30mm mild steel zinc plated, suitable for indoor applications.
• A2 Stainless Steel (A2-70): Resistant to corrosion and high temperatures.
• Example: A2-70 grade U-Bolt in size M10 x 50mm, used in marine environments with a load rating of up to 35kN.
• A4 Stainless Steel (A4-80): Superior corrosion resistance compared to A2.
• Example: A4-80 grade M16 x 75mm U-Bolt for use in chemical processing plants with a pressure range of up to 25 bar.
• Hot-Dip Galvanized (HDG): Provides excellent protection against atmospheric corrosion.
• Example: HDG grade U-Bolt size M14 x 60mm, ideal for outdoor pipe clamps with a temperature range from -30°C to +500°C.

Selection Criteria

Choosing the right U-Bolt involves considering several factors:

• Pipe Diameter: Ensure that the U-Bolts' inner diameter matches or slightly exceeds the pipe's outer diameter.
• Load Requirements: Check the load rating against the application's requirements, typically found in manufacturer specifications.
• Environmental Conditions: Select materials based on environmental exposure (e.g., salt water, high humidity).
• Installation Space: Consider the space available for installation and ensure the U-Bolt fits properly.

UK Suppliers

MLC lists verified suppliers from Companies House that offer a wide range of U-Bolts. For instance:

• CBM Ltd supplies A2-70 stainless steel U-Bolts.
• BIAFD (British Industrial Fasteners Association) provides HDG and mild steel options.
• BTMA (British Template Manufacturers' Association) offers precision-engineered square bend U-Bolts.

Common Applications

U-Bolts are widely used in various industries:

• Pipe Clamps: Secure pipes to supports, ensuring stability and preventing movement. They adhere to BS 3974 standards.
• Exhaust Hangers: Used in automotive exhaust systems to support heavy components and absorb vibrations.
• Leaf Spring Mounts: Critical for vehicles where U-Bolts secure leaf springs to the chassis.

With proper selection based on material, load requirements, and environmental conditions, U-Bolts can provide reliable support across different applications.