M4 M16 Carbon steel U type metal bolt with nut washer Class4.8 grade 8.8 Black Blue U bolt

U-shape bolts are generally used in cargo vehicles to stabilize the chassis and frame of the vehicle. For example, the steel plate spring is connected using U-bolts.

U bolts are widely used in:

• Construction and installation
• Mechanical parts connection
• Vehicles and ships
• Bridges, tunnels and railways

Main shapes: Semi-circular, square right angle, triangle, oblique triangle, etc.

• Density, bending strength, impact toughness, compression strength
• Modulus of elasticity, tensile strength, temperature resistance
• Color according to the use environment

Common materials: Carbon steel Q235A Q345B, alloy steel, stainless steel (201, 304, 321, 304L, 316, 316L)

National standard: JB/ZQ4321-2006

The surface treatment of bolts is divided into the following methods

Oxidation black. There are also blue-black, generally oxidised and coated with anti-rust oil.
Phosphating. General phosphating to be coated with oil.
Electroplating. Mainly electroplated zinc, as well as chromium plating, nickel plating, silver plating, etc.
Hot-dip zinc.
Galvanising.
Non-electroplated zinc flake coating. Dacromet in a broad sense, but also divided into zinc-chromium coating, zinc-aluminium-chromium coating.
According to the colour, blue, silver white, silver grey, copper yellow, black, green and so on.

U-bolt heat tightening is suitable for occasions where the internal temperature requirements of the pipeline bolts exceed 200°C. In addition to the construction fastening, it requires reaching a constant temperature or different temperatures in a process of work before fastening.

With growing environmental awareness, the environmental performance of U-shaped bolts has become a focus. In production, using eco-friendly materials and processes to reduce energy consumption and emissions has become an important development direction.

U-bolts are essential in:

• Construction, machinery, automotive (traditional fields)
• Aerospace, new energy (emerging fields)

• Superior corrosion protection for iron, steel or other metals
• Relatively inexpensive compared to other corrosion protection methods
• Enhanced strength, toughness, and abrasion resistance
• Easy to clean metal hygiene
• Longevity with life expectancy of 20-25 years
• Easy to repair affected areas
• Simple visual inspection methods
• Aesthetically appealing shiny silver appearance

• Limited to few metals like iron and steel (not suitable for aluminum alloys)
• Not effective in very acidic and salty environments
• Zinc coatings can be damaged at high temperatures
• Potential for 'white rust' with prolonged moisture exposure