A U bolt is also called a U bolt clamp or U clamp, it is a threaded u shaped fastener that can hold electrical poles or other structures on the electric power line, pole line, and concrete line.

Different countries use varying designs of U bolts, there are square U bolts, round U bolts, U bolt clamp brackets, and middle bandage U bolts which are installed on the concrete pole to fasten the cross arm. There is a small u bolt that is used to connect the ball socket and tension clamp on the transmission line.

The surface treatment is hot-dip galvanized. The zinc thickness will protect the surface from getting rusty.

The U bolt thread is made by the rolling machine. There are 1/2’’, 5/8’’, and 3/4’’ diameter screws. As an ISO-certified manufacturer, supplier, and exporter, Quan Pham Industry also can customize sizes and produce new designs according to customers’ drawings or requirements. We have successfully exported the square U bolt to Chile and Kenya.

All the U bolts are assembled with two or four hex nuts or square nuts.

Why do customers choose Quan Pham Industry U bolt?

All the Quan Pham Industry U bolts are hot forged, not cold bend. The hot-forged U bolt guarantees high loading strength in the 11kv/ 33kv overhead line.
After U bolt galvanizing, Quan Pham Industry workers sprinkle oil on the thread to guarantee a smooth installation
The factory price for U bolts will save your cost.
If you are searching for good quality U bolt, please contact us.

U Bolt: The Complete Guide

In case you want to support pole line hardware, you may need a U bolt clamp.

It is because a U bolt is an effective and reliable fastener when it comes to this.

However, you must choose high quality and reliable U bolt.

That’s why today, I am going to show you how to find one.

I will walk you through all the fundamental aspects – from the definition, types of U bolts, main components, the installation process to technical specifications, among other vital aspects.

Let’s dive right in.

What is a U Bolt?

A U bolt clamp is a type of bolt that has the shape of the letter U and has screw threads on each end.

It is common to see them in use on electric power lines, concrete lines, and pole lines.

You will realize that the types and designs of U bolts vary as you move from one country to another.


U Bolt

u bolt measurements

The bolts vary in size ranging from 5/8 inch, ¾ inch and ½ inch diameter screws. Rolling machines are used in making the threads on both ends of the U bolts.

All U bolt assembly includes two- or four-square nuts or hex nuts.

Types of U Bolts

There are two main types of U bolts including the square U bolt and the middle bandage U bolt.


U Bolt

Types of U bolt

They are both used on concrete poles to fasten cross arms.

There are, however, smaller U bolts used in connecting ball sockets and tension clamps on transmission lines.

· Square U Bolt

It is a type of U bolt that is bent at 90 degrees at each bend.

U Bolt

Square U bolt

It is also known as the square bend U bolt.

The square U bolt is in common use in countries such as Kenya and Chile.

· Middle Bandage U Bolt

It is another type of U clamp with a bandage in the middle usually between the threaded ends.

The bandage is supposed to reduce friction between the U clamps and the installed device.


U Bolt

U bolt with a plate

The bandage is available on the square U bolt too, depending on the use.

Why You Need U bolts

U bolts are important features in pole line hardware because they help in fastening many components on the pole.


U Bolt

u bolt bracket applications

It provides support for the appliances such as the electrical cross arm and holds them in place.

They are also used on electric power lines, pole lines, and concrete to fasten the adjacent components.

Main Components of U Bolts

U bolts are very simple devices with a bolt in a U shape and two nuts on both ends.

There are other U bolts that have washers to help in making the connections tighter.

The washers are also important as they hold the nuts in place in case of a shaky structure.

Nuts are types of fasteners on the U bolts with threaded interiors.

They often work in conjunction with the bolts holding together due to friction along with the treads.

The other forces that keep them together are stretching, elastic deformation, and compression.

A washer is a thin disk-shaped plate with a hole at the center made of plastic or metal.

It works better in the distribution of load on the threaded fasteners.

It can also function as a spacer, wear a pad, spring, locking device, and preload indicating device among others.

Technical Specification of U Bolts

Before buying a U Bolt, you should consider the following:

Technical specification of a U bolt

Technical specifications of a U bolt


Making a U bolt requires you to know the measurements of the kind of work you will use it on.

Measuring is done through cross-arm engineering speak since the U bolt functions best on cross arms.

In measuring a U bolt make sure that you include:

  • Inside height
  • Thread size
  • Inside diameter
  • Thread length

Apart from that, you will also have to mention other dimensions such as the type of material.

All the measurements of length and width are in millimeters.

Material Type

The most common type of material used in making U bolts is stainless steel.

Steel is the best material because of its strength and cannot break easily.

It also passes through the hot-dip galvanization process making it resistant to corrosion.

Finish – hot-dip galvanization

Hot-dip galvanization is a process where U bolts pass through to give it corrosion resistance properties.

Steel is passed through liquid zinc adding an extra coating to keep the rust away.

The process works well at different temperatures depending on the type of material used.


The thickness of the U bolt depends on the type of cross arm it is going to hold.

Heavy materials require the use of thick U bolts because they can carry the weight.

This is the reason why U bolts are available in different diameters for you to choose from.


U bolts do not have a lot of design on them because of the kind of material they hold.

The most important determinant of the type of design on U bolts is the material it contains.

The most common models of U bolts are the middle bandage U bolts and the square U bolts.

Tensile strength

The tensile strength of the U bolts relies on the material used in making them.

The diameter of the element also influences the tensile strength of the U bolt.

You will even realize that the process of manufacturing U bolts will determine the power of the U bolt.

For instance, hot forging makes the U bolts stronger with a tensile strength of 11 kV or 33 kV.

U bolts manufacturing using a cold bending process are very fragile, and you should not use them.

U Bolts Manufacturing Process

U bolts pass through the process of hot forging, and it is hazardous to cold bend.

Hot forging U bolts make sure that they have very high loading strengths in 11kv or 33kv overhead lines.

Manufacturers sprinkle oil on the threads of the U bolts for a smoother and better installation experience.

The process of manufacturing U bolts requires the primary raw material which is steel.

Apart from that, it needs a rolling machine that will help in making the treads.

Measuring and cutting materials are also required.

The first step is gathering all the material required and making the right measurements before making the necessary cuts.

Normally, the measurements on the materials are per the dimensions of the desired U bolt.

The customer has the freedom of making requests on the kind of U bolt he will need.

Also, the second process is precarious, and you have to be very careful since it involves working with fire.

In this case, steel passes through the process of hot forging where it is bent.

It is easier to bend the steel while it is still hot as it will also increase the strength of the bolt.

Cold bends may break the steel or make it fragile for use in heavy jobs.

Make sure that you wear protective gear during the process of hot forging.

The threads on the bolts are a result of rolling them on a rolling machine.

The diameter of the bolt and the number of threads on the U bolt are in place before rolling.

The last step is hot-dip galvanization where the metal passes through liquid zinc.

This offers corrosion-resistant properties making it durable and stronger.

Step-by-step U Bolt Installation Process

U bolts are easy to install as compared to other pole line hardware.

You will, however, require the assistance of an expert to guide you in the process.

Apart from that, an assistant should be available to help you in making the installation.


U Bolt

U bolt Installation

Depending on the type of installation, make sure that all the components are in place.

In this case, you are going to use a U bolt in fastening an electric cross arm.

You will need a ladder to elevate you to the height where the cross arm is.

Make sure that the cross-arm is in place and with the assistance of a drill make holes on the pole.

The holes are supposed to be broad enough to allow the bolt to pass through.

It should also leave enough space for the nuts and the washers.

After drilling the holes, request your assistant to hold the cross arm in place as you fix the bolts inside the holes.

The U bolt should fit well in the gaps and attach the electrical cross arm correctly.

Fit the washer and then the nut and fasten it to the end of the available thread.

Use devices such as spanners and pliers to lock the nuts tighter, holding the cross arm in place.

Frequently Asked Questions (FAQs)

What is a U Bolt?

A U Bolt is a threaded fastener that is designed to fit over a round item such as an exhaust pipe, conduit and is threaded on both ends to accept an appropriately sized nut.

What types of steel are used to make U-bolts?

It is not the same in different markets, take the Philippines for example, they use standard available material types include stainless steel, hot-dip galvanized carbon steel, zinc plated carbon steel, and plain carbon steel.

What is a U Bolts coating?

The surface treatment is hot-dip galvanized. The zinc thickness will protect the surface from getting rusty.

How to choose the manufacturer of u bolts?

Here are the guidelines that can help you choose a suitable manufacturer:

  • Check whether the company is licensed
  • The production capacity of the company
  • Look for the reviews about the manufacturer
  • Experience of the manufacturer


U bolts are essential parts of pole line hardware as they hold the other components in place.

The guide on U bolts is supposed to help you understand the kind of choices you need to make.

Remember that U bolts can also be custom-made, so you have the freedom to make an order.

Here at Quan Pham Industry, we strive to give you the best U bolts.

Talk to us today, and our team will help you.

U BoltU Bolt

SIZE Dia. Ins. Width Ins. Length Thd
(D) (C) (L) (T)
1/2 x 1 1/2 1/2″ 2″ 3″ 1 1/4″
1/2 x 2 1/2″ 2 7/16″ 3 5/8″ 1 3/4″
1/2 x 2 1/2 1/2″ 3″ 4 1/8″ 2″
1/2 x 3 1/2″ 3 9/16″ 4 1/2″ 2″
1/2 x 3 1/2 1/2″ 4″ 5 1/2″ 2″
1/2 x 4 1/2″ 4 9/16″ 5 3/4″ 2″
1/2 x 5 1/2″ 5 9/16″ 7″ 2″
1/2 x 6 1/2″ 6 5/8″ 8″ 3″
1/2 x 8 1/2″ 8 3/4″ 10 1/4″ 3″
1/2 x 10 1/2″ 10 7/8″ 13″ 3″
5/8 x 5 5/8″ 5 9/16″ 7″ 2″
5/8 x 6 5/8″ 6 3/4″ 8 3/4″ 3″
5/8 x 8 5/8″ 8 3/4″ 10 1/4″ 3″
5/8 x 10 5/8″ 10 7/8″ 13″ 3″
3/4 x 8 3/4″ 8 3/4″ 10 1/4″ 3″
3/4 x 10 3/4″ 10 7/8″ 13″ 3″
3/4 x 12 3/4″ 12 7/8″ 15″ 3 3/4″

U bolts sizes chart

Product Specifications
Product Name U Bolt
Code JY-UB-5/8
BOLT Diameter 5/8″ OR 1/2″
Product Finish Hot Dip Galvanized
Material Steel Rod
Standard Package Carton or woven bags
Standard ASTMA-123
Production time 3-4 weeks/10000pcs
Payment item T/T 30% DOWNPAYMENT