A double arming bolt is also called double threaded bolt, double ended bolt, or DA bolt. According to the length of the thread, the double arming bolts include all thread bolts and double threaded bolts.

The double ended bolts are widely used on the pole line and cross arm construction. As all-thread bolts go through the pole, the two ends of the double arming bolt will be locked and secured by nuts and washers. At the same time, one end of the double arming bolt will connect with eye nuts for dead-end application.

The double threaded bolt also performs an important role when installing two cross arms on the pole. The double arming bolt will secure the space between the two cross arms and fasten the two cross arms tightly. This way, the cross arms are supported on the pole firmly together with the cross arm brace assembly.

Quan Pham Industry double ended bolts are made from steel rods. The production of the double ended bolt screw thread is by a rolling swaging process using hardened profiled rollers. Rolled threads are stronger than threads machined by a cutting tool

Quan Pham Industry double arming bolt has 12400 pounds rated tensile strength and is finished with hot-dip galvanized.

As a professional manufacturer, supplier, and exporter, Quan Pham Industry can support all sizes of double arming bolts, We can also customize them according to your designs.

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Double Arming Bolt: The Complete Guide

Double arming bolt is one of the finest pole line and overhead line systems for telecommunication and electrical industries.

In this guide, I am going to show you how to choose a suitable double arming bolt.

Among the key things, you will learn about these industrial fasteners include specifications, designs, installation process, etc.

To learn more about this accessory, read on.

What is a Double Arming Bolt?

This is what double arming bolts look like:

Double Arming Bolt

Double arming bolt

As you can see, it is a simple accessory, yet it plays an important role in transmission and distribution lines.

Remember, the double arming bolt is also called a double threaded bolt or double ended bolt.

Uses of Double Arming Bolts

Double arming bolts are used for cross arm and pole line construction purposes.

That is one reason they are very famous.

Due to the fact that their threads are manufactured to go through the poles, their two ends are always locked and kept very safe by washers and nuts.

Double arming bolts are made to help in the cross arm construction and pole line.

They are designed in a way to make their use very easy.

These double threaded bolts play a vital role when you want to install two cross arms on these poles.

It works by securing spaces between two cross arms and fasten two cross arms tightly.

Double Arming Bolt

Double arming bolt

Parts and Components of the Double Arm Bolt

It is important for you to know the uniqueness of double arm bolt parts and components.

This will help you when shopping for a suitable double arming bolt for your utility lines.

Below are some of these bolts:

  • Threaded bolts

Threaded bolts are designed to easily move through the poles and ensure nuts and washers are locked well.

Double Arming Bolt


Without these threads there is no way fastening can be as tight as it should be.

  • Nuts

Nuts are vital because they help with the fastening process.

Without nuts, there is no way you can have a proper installation in pole lines.

Double Arming Bolt

Different types of nuts

When nuts are fastened well, it helps to keep all cables and pole lines stronger.

  • Washers

It is an important aspect of the installation of double arming bolts.

They help distribute pressure on the surface you’re tightening, hence protecting it from possible damage.

Double Arming Bolt

Different types of washers

Also, it prevents the nuts from loosening when the surface of the pole is not even.

Now, how about the design of double arming bolts?

Double arming bolts are manufactured with chamfered ends that are round and semi-coned types.

Such cones are made to point at all ends of double arming bolts.

It aids you in driving and removing it from poles with so much ease.

Besides, you will not damage the threads.

They are mainly made from stainless steel, which can be hot dip galvanized.

Of course, you can find double arming bolts made from other materials too.

How to Install a Double Arming Bolt on Pole Line

Installing double arming bolts is simple and straight forward.

Double Arming Bolt

Double arming bolts

Here is what you should do:

  1. Start by assembling all the necessary tools and equipment. For instance, in case the poles do not have holes, you need a drill.

Also, you need appropriate fasteners.

This will depend on the size of double arming bolt.

  1. You can start by disassembling the nuts and washers from the bolt. In most cases, the double arming bolts come with four square, hex nuts or nuts based on your needs.
  2. Now insert the chamfered round ends of the double arming bolt into the hole in the pole. Push it slowly until it penetrates through to the other end.
  3. You can put another pole line hardware you want to secure using a double arming bolt.
  4. With all pole line hardware in place, you can insert the washers, then fasten the nuts on both ends.

And there you are, you have successfully installed a double arming bolt.

Double Arming Bolt Specifications

Now, before you go shopping for a double arming bolt for your hardware, it’s important to know the specifications to look for.

Double arming bolt data sheet

Double arming bolt data sheet

That’s what I am going to show you in this section:

i. Diameter

Double arming bolts come in different diameters depending on the nature of the application.

For instance, you can choose from 5/8, 1/2, to 3/4 inches with various lengths.

Even custom sizes are available upon request.

Alternatively, you can choose a complete thread double arming bolt and two end thread types.

Their sizes are mostly ¾ inch and 5/8 inch.

Note: Diameter determines the amount of load double arming bolt can handle.

ii. Type of material

You can choose from a range of materials.

However, stainless steel is a popular material for most pole line double arming bolts.

Of course, you can also choose a material that meets your unique specifications.

And, more importantly, the supplier should be able to process it successfully.

Double arming bolt screw thread is made by rolling swaging process with hardened profiled rollers.

Tolled threads are very strong compared to machined threads.

iii. Length

Apart from diameter, the length of a double arming bolt is also a critical feature.

This length is measured from its last thread, end to end without the length of cones.

Depending on thread length, double arming bolt will always come in double threaded among other options.

In short, the length of the double arming bolt will determine the specific application.

iv. Breaking load

It refers to the amount of load a double arming bolt can support.

It depends on different designs, so you must be specific on this.

v. Type of nuts

Depending on the design, this accessory comes with different types of nut designs.

But more importantly, the nut should be easy to fasten.

For instance, they may feature hex nuts, square nuts, etc.

vi. Hot dip galvanized

Proper finishing will determine how long a double arming bolt will endure external weather conditions.

From experience, I can recommend double arming bolt with hot dip galvanized finish.

And, as a rule of thumb, always read the instructions that the products come with.

Frequently Asked Questions (FAQs)

What is the double arming bolt mainly used for?

The double arming bolt is mainly used on the pole line and overhead line construction.

What are the types of your double arming bolts?

There are many kinds of double arming bolt in the factory, such as full thread double arming bolt and two end thread double arming bolt, mainly size is 3/4 inch and 5/8 inch. We also supply OEM/ODM.

What is the standard of the double arming bolt?

The double arming bolt is made according to UNC or BSW.


I hope you have learned a lot about choosing the right double arming bolts – from the basic definition, installation process, and parts to technical specifications.

With this information, you should be able to buy high quality and reliable double arming bolts.

But, wait a minute!

Do you need pole line hardware or just a double arming bolt?

Well, Quan Pham Industry is here for you – talk to us today to get a double arming bolt.

Each double arming bolt is assembled with four square nuts or hex nuts according to the requirements of the customer. All the double ended bolts have semi-cone points or chamfered round end. The cone points at both ends of the double arming bolt help to drive and remove it from the pole easily without damage to the thread. The double arming bolt length is measured from the last thread, end to end without the length of the cone. The widely used double arming bolt diameter is 5/8, 3/4 and 1/2 inch with different lengths.

Product Specifications: Double Arming Bolt
Code D L Breaking load strength Nuts Surface Treatment
Hex Nuts NO. Size m (mm) s (mm) e (mm) Hot dip galvanized
JY-B-1B 5/8″ 10″ (250mm) 55.2kn 4 M16 14.5 26.75 24 Hot dip galvanized
JY-B-1C 5/8″ 12″ (300mm) 55.2kn 4 M16 14.5 26.75 24 Hot dip galvanized
JY-B-1D 5/8″ 14″ (350mm) 55.2kn 4 M16 14.5 26.75 24 Hot dip galvanized
JY-B-1F 5/8″ 18″ (450mm) 55.2kn 4 M16 14.5 26.75 24 Hot dip galvanized
JY-B-1G 5/8″ 20″ (500mm) 55.2kn 4 M16 14.5 26.75 24 Hot dip galvanized