Many engineers and welders find themselves confused with the difference between stitch welding and seam welding since they are often used interchangeably, but there is a definite difference between the two types of welds. In the welding fabrication world, it is important to distinguish the two because both welds are have different strength properties and are used for different purposes. Below are photos of each type of weld and a description describing the two.
How to Call Out a Stitch Weld on a Drawing:
Stitch welds generally have two numbers next to the weld call out to represent the length of the stitch weld and the pitch of the weld. The length is the length of the actual stitch weld. Whereas the pitch number is the distance between the centers of two stitch welds. Below is an image from Delta School of Trade that clearly represents the weld call out and the numbers for an intermittent weld.
Stitch Weld
Also known as intermittent weld. Stitch welding is not a continuous weld across a joint, but a weld broken up by space gaps in between welds, which results in a “stitch” look. It is not as robust and durable as a seam weld. It is used to prevent heat distortion and to also reduce the cost of welding if a long continuous weld is not necessary. There are two common types of stitch welds, fillet weld and butt joint weld. A fillet weld is a triangular seam weld that joins two surfaces at right angles to each other. Butt welds are generally in a lap joint, T-joint, or corner joint, which is most common amongst welding pipe or tubes to another surface where two pieces of metal are positioned coplanar and touching on one edge. Below are two photos of stitch fillet welds.
Fillet stitch weld
Butt stitch weld
Seam Weld
Also known as continuous weld. Seam welding is a continuous weld along a joint. Seam welds can be in the form of a fillet weld and a butt joint weld. Seam welding is robust and is more durable because of the amount of surface area that is joined by a weld. There are two common types of continuous welds, fillet weld and butt joint weld. A fillet weld is a triangular seam weld that joins two surfaces at right angles to each other. Butt welds are generally in a lap joint, T-joint, or corner joint. This is most common amongst welding pipe or tubes to another surface. Below is an image of a fillet seam weld:
Fillet Seam Weld
The other common seam weld is a butt joint weld. This is where two surfaces butt up against each other creating a single plane surface. A seam butt joint weld is one of the most common types of welds. Below is a photo illustrating a continuous butt joint weld:
Butt Joint Seam Weld
We hope this clears up any confusion between the two types of welds. Be sure to visit our welding sections of our website to learn more about the different types of welding that we do in-house. If you are looking for a quality fabricator that specializes in precision welding services and is AWS Certified, you’ve come to the right place. We also provide sheet metal fabrication and CNC machining services! Contact us today and provide us with dimensional prints for a quote.