What is Tack Welding? How Important is It?

What is Tack Welding

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Tack welds form an essential part of most welding jobs despite seeming more transient and insignificant. For most projects that entail joining two metal surfaces or pieces, these welds will always come in handy. Therefore, as a welder, you need to understand what they are all about, their benefits and how to do them correctly to avoid the potential risks of defective ones.

What is Tack Welding?

The American Welding Society defines a tack weld as a joint used to hold parts of a weldment in proper alignment until the welder can or finishes making the final welds. In other words, the tack welds help keep different metal parts and surfaces together to allow for a more stable final weld.

With a tack weld, the welder can often avoid using other methods of keeping parts together before welding, such as clamping them as they are not always very stable. When doing tack welding, you will not need any extra tools, and you just need to do short welds at the ends and middle.

While tack weld sizes are not specified, they are often between 1/2 and 3/4-inch long, and even if you prefer slightly longer ones, they never exceed 1-inch. The thickness of your material and other things like the welding job’s complexity should help you determine the number and size of tack welds you need.

Benefits of Tack Welding

Benefits of Tack Welding

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Although tack welds are temporary, they are still vital for many welding jobs as they come with various benefits. Here are some of the main benefits you get from using these welds.

1. Maintains Correct Alignment

When doing larger welding jobs where you have to weld multiple areas and parts, it is not easy to keep the different sections correctly aligned, even when using several clamps. You can align the joint correctly with tack welds before starting the final welds, ensuring better outcomes for both novice and expert welders.

2. They Are Easily Removable

Unlike the more permanent weld types, the tack welds are easy to remove. The advantage of this is that it makes rectification easy if you find issues with things like the alignment or do something incorrectly. You do not get this luxury with final welding as it is hard to undo without ruining the material.

3. Helps Maintain Joint Gap

Tack welds provide one of the best and easiest ways to maintain the joint gap at the right place and value. When doing the finals welding, it can be hard to preserve joint gaps just by looking at them no matter how experienced you are, but with tack welds, you can set everything correctly with no guesswork.

4. Allows for Easy Workpiece Movement

If you have to move your workpiece a lot when welding, you need tack welds. These welds hold everything together to allow you to move the piece or material as many times as you want without affecting the different parts’ location or orientation.

5. Reduces Need for Permanent Fixtures

Using the tack welds can reduce the need to have permanent fixtures like clamp systems for holding material together in your workshop. Hence, they save you money and much-needed workshop space.

Risks of Defective Tack Welding

  • Property Damage and Injury: Defective tack welds can lead to damages to your property and also cause injuries because defects like cracks, slag, and hard spots can cause the entire workpiece to fall apart.
  • Degrading Quality of Final Welding: Despite being small and removable, when not done correctly, tack welds also have the potential to degrade the quality of the final weld you make.
  • Ruining the Materials: Most steel materials are susceptible to rapid cooling. Things are even worse after a short tack weld as there is more rapid cooling since this weld requires less heat. Sometimes the rapid cooling creates brittle microstructures on the metal that crack easily when rapidly quenched even after removing the tack weld.


Tack welds are highly useful for most welding projects as they contribute significantly to ensuring you always end up with perfectly aligned pieces. These welds come with many other benefits for your project, but it is crucial to make sure you do them properly to avoid the potential risks of defective ones.


  1. Tack Welds – American Welding Society
  2. Tack Welding Tips – DIY Network
  3. Tack Welding – The National Board of Boiler and Pressure Vessel Inspectors