Seam Welding Process Application & Seam Welding vs Spot Welding

There are many different techniques employed in welding and one of the most useful to learn is seam welding. So what is seam welding and why should you as a welder care? Used mainly in the welding fabrication world this type of welding produces robust and durable welds.

In essence, seam welding is the best technique to use when you want to join two surfaces. There are many things you can do with seam welding. This is why it’s a useful welding process to learn. 

That being said, in this article, we will be taking a closer look at seam welding. In particular, what is Seam Welding and how it Works? Also, we will be looking at the pros and cons of using this welding technique.

What is Seam Welding?

Sometimes referred to as resistance seam welding, seam welding is a procedure that entails the joining of two similar metals. In other words, it is a continuous weld along a joint. Though different from butt welding, this type of welding can be used to produce butt joints.

It is common for people to mistake seam welding with spot welding. The reason being that they are similar in many ways. Both utilize two electrodes usually made of copper instead of one. 

In seam welding, the disc-shaped electrodes rotate while the material being welded passes through them. Thus, the electrodes are in continuous contact with the materials being welded.

seam welding process

Seam Welding Process: The Working Principle

While there are some clear differences between seam welding process and other welding processes, it largely follows the same welding principles. As such, you need a power source to provide low voltage and high power AC.

The joint is heated to its melting point by the continuous flow of the electric current. When the joint reaches its melting point the semi-molten surfaces are joined together. The resultant fusion bond is usually as a result of welding pressure.

Seam Welding Applications : Why Seam Welding

Seam welding is necessary for fabrication. This type of welding process is used to make steel beverage cans. Also, it is a process used in the manufacture of steel tubing. Since you can achieve both fillet and butt joints it is used to make rectangular and round steel tubing.

Also, this type of welding process is commonly used in vehicle manufacturing. Components such as petrol or diesel tanks are fabricated using this welding technique. Domestic radiators and even steel drums are also fabricated using this welding process.

Seam welding precautions

The seam welding process generates intense heat. As such, there are some precautions you must take when using this technique. This includes wearing protective gear, a welding mask, and gloves. 

Also due to the intense heat produced be sure to have a water supply nearby. This will help in cooling the electrodes when they become too hot. The transformer and controller assemblies will also require cooling.

Advantages and Disadvantages of seam welding

Advantages of seam welding

  • Creates watertight and airtight seals and is best for fabricating components that need air or water leakage protection
  • Unlike other welding processes, this one does not require filler or flux material
  • Due to the process being automated it is faster than other similar processes such as spot welding
  • It is possible to produce single seam welds and parallel seams simultaneously
  • The joints created using this welding technique are usually strong and robust

Disadvantages of seam welding

  • Due to the apparatus used only straight or uniformly curved lines are achievable with this welding process
  • Welding sheets that are 3mm thick and beyond is difficult and cumbersome and is not recommended.

Types of Seam welding

Seam welding processes can be classified into two, continuous and intermittent. This two types of welding techniques differ. Let’s take a look at each individually.

1.Continuous seam welding

In this welding technique, the electrodes rotate at a consistent and predetermined speed. This is done to create an overlapping weld. To achieve this type of weld timed current impulses are needed to create an overlapping weld

The same can be achieved by moving the workpieces at a consistent speed between the electrodes. In this type of weld, sheets are arranged in small overlaps over the other. The sheets are then mashed together.

The result is usually a joint that is 10 to 50 percent thicker than the original sheet. It may be necessary to do some post-weld planishing to reduce the thickness of the joint.

2.Intermittent seam welding

In intermittent seam welding, the current pulses are passed intermittently. The current pulses combined with the pressure created by the wheels create separate spot welds. This type of welding allows the workpiece to move from one weld position to another.

This type of seam welding is suited to welding thicker materials and in particular those that are resistant to continuous seam welding.

Types of joint used

Ideally, there are two types of joints used in this kind of welding fillet weld and butt joint weld. A fillet weld is a triangular joint weld that connects two surfaces together at right angles. A butt joint weld, on the other hand, is a joint weld where two surfaces butt up against each other.

In a butt joint weld, the surfaces connect to create one single plane surface. This type of joint is the most common in seam welding.

Seam Welding vs Spot Welding

Seam welding Vs Spot Welding

As mentioned earlier it is easy to mistake seam and spot welding. These two types of welding processes have a lot in common. However, they also differ in more ways than one. In spot welding, the sheet materials are held between copper electrodes and current passed through them.

spot welding

As such, the electrodes in spot welding do not rotate. The point where the surfaces come in contact with each other receives high temperatures and is where fusion takes place.  In seam welding, disc-shaped electrodes that rotate are used.

Both do not require flux or shielded gas. Spot welding is best suited to welding smaller sheets of metal. And is more common than seam welding, which is more common in industries and construction sites.


Seam welding produces strong and robust welds. This welding process has many uses and there are many places where you can use spot welding machines. Furthermore, this type of welding process does not require flux or shielded gas like other welding processes.