What is Backing in Welding?

The backing is a material (base metal, weld metal, or granular material) placed at the root of a weld joint for the purpose of supporting molten weld metal. The backing provides better welding performance by preventing root pass penetration, promoting rapid cooling and solidification of the weld pool, and protecting the back side of the joint from oxidation and contamination.

There are several different types of backing materials that can be used in welding, including:

Base metals: Base metals such as mild steel or stainless steel can be used as backing materials. These materials are often used for gas tungsten arc welding (GTAW) or shielded metal arc welding (SMAW).
Weld metals: Weld metals such as aluminum or copper can be used as backing materials. These materials are often used for gas metal arc welding (GMAW) or flux-cored arc welding (FCAW).
Granular materials: Granular materials such as sand, glass, or ceramic can be used as backing materials. These materials are often used for gas tungsten arc welding (GTAW), plasma arc welding (PAW), or electron beam welding (EBW).

Backing materials are typically placed on the back side of the joint, away from the heat source. This allows the backing material to cool quickly and helps prevent it from becoming molten.

Backing materials can be used with all types of weld joints, including butt, lap, T-joints, and corner joints. However, they are most commonly used with butt joints.

Backing materials are not required for all welding applications. In some cases, they may actually hinder welding performance. For example, backing materials can increase welding distortion and porosity if they are not properly chosen or placed.

What to use as backing for welding?

The type of backing material you use will depend on the welding process, the materials being welded, and the desired results. Some common backing materials include mild steel, stainless steel, aluminum, copper, sand, glass, and ceramic.

What is the difference between back and backing welds?

Back welds are welds made on the back side of a joint, away from the heat source.
Backing welds are welds made on the back side of a joint, near the heat source. Backing welds are used to support molten weld metal and prevent it from penetrating through the back side of the joint.

What is a backing strip used for in welding?

A backing strip is a thin piece of metal placed at the root of a butt weld joint. It is used to support the molten weld metal and prevent it from penetrating through the back side of the joint.

Retainers in welding

Retainers are placed on the back side of the joint and welded in place. They help to hold the molten weld metal in place and prevent it from penetrating through the back side of the joint.

Copper backing for welding

Copper backing can be used for gas metal arc welding (GMAW) or flux-cored arc welding (FCAW). It is often used to weld stainless steel or aluminum.