What Are the 5 Basic Types of Weld Joints? Diagrams & Descriptions
Seasoned welders can make the work of piecing metal together look easy. But the job requires more than picking up a torch and connecting metal to metal. You need to be skilled in several welding techniques and joint types and know how to protect yourself and your environment during the process. A weld joint is that spot where two or more pieces of metal are fused together through the process of welding. Heat and pressure come together as the basis of all metal structures, from buildings and bridges to metal crates and frames. Check out our comprehensive weld joint guide to find out when to use which techniques and how they can all work together.
Understanding Weld Joints
When the surfaces of two or more pieces of metal touch, they form a weld joint. Weld joints can be formed from all sides and angles to allow for proper distribution of weight and stress. Different weld joints can handle the forces of stress, such as compression, shear, and torsion, in contrasting ways so it’s important to pick the right weld joint type for the job. For example, if you work on cars or buildings, tee joints are the best option for many applications. For furniture and metal framework, corner joints are the more common weld joint.
The 5 Basic Type of Weld Joints
As you learn welding, you find that there are many different types of weld joints, but some are more commonly used than others. Here are some examples:
1. Butt Joint Weld: Characteristics and Applications
Butt joint welds are one of the simplest weld joint types to create. This weld joint combines two pieces of metal that abut each other,1 or are placed side by side on the same plane. Often used to connect metal plates or pipes, butt joint welds, can be created using MIG, TIG, and stick welding. There are different types of butt joints including grooving and beveling, which can make the weld stronger.
2. Lap Joint Weld: Advantages and Limitations
Commonly used when materials have different thicknesses, lap joint welds1 connect overlapping pieces of metal. For example, a lap joint might be used in automotive bodywork during the assembly or repair of vehicle parts. The advantage of this type of weld is that it provides extra strength and stability. But The limitations of this weld include corrosion between the metals and lamellar tearing. Lamellar tearing is a type of weld defect caused by internal stresses from the welding process but can be avoided with a trained hand.
3. Tee Joint Weld: Uses and Considerations
Tee joint welds1 are formed when two pieces of metal meet and form a “T” shape, at a 90-degree angle. This weld can be used to weld beams, support frames, or connect pipes and tubes to a base. If the base is thick, the metal can be prepared with grooves for welding. One disadvantage of tee joint welds is that they can be susceptible to stress concentration where the two pieces of metal meet. That spot can crack or fail under heavy loads if the weld isn’t done properly. If the weld doesn’t fully fill the joint, it can also cause week spots. Lamellar tearing is also a frequent problem with tee joint welds but can be combatted with a stopper.
4. Corner Joint Weld: Techniques and Common Applications
Corner joints1 are formed when two pieces of metal meet to make a corner, or “L” shape. Commonly used to fabricate sheet metal into boxes, frames, and enclosures, this type of weld joint is applied at the intersection of the two pieces of metal. There are two types of corner joints – the butt square, which places the ends neatly next to each other, and the V groove, where only the tips of each end touch, creating an empty V-shaped space behind the joint. It can be created with different kinds of welds, including fillet or groove welds.
5. Edge Joints: Benefits and Challenges
An edge joint weld2 is a type of weld where two metal pieces are placed side by side with their edges next to each other. The edges should be even, and the plates can sometimes be bent at an angle. The benefit of edge joints is that they are sturdy and distribute weight and stress evenly. But the surface-to-surface nature of this weld can lead to corrosion and high porosity. This type of joint is often used when the metal pieces are thin and don’t require significant structural strength, or when they need to be joined along their length to prevent leakage, such as in sheet metal fabrication or tanks.
Other Types of Weld Joints
In addition to the five common weld joints, there are others that are more complex. For example, diagonal weld joints join two pieces of metal at an angle less than 90 degrees. Multiple joints, also known as corner kicks, combine three or more pieces of metal and they don’t have to be perfectly aligned. Parallel joints combine two pieces of metal that are next to each other and flanged or crimped joints join two pieces of bent metal at the rebate.
Improving Weld Joint Performance
The durability of the final product you make depends on the quality of your weld. Here are a few tips to avoid common defects:
- Properly Align Your Clamp and Workpieces – This can help avoid cracking, which occurs when the weld cools too quickly or when there is too much stress on the joint.
- Use the Correct Shielding Gas – If you don’t you could trap gas in the weld, causing porosity.
- Avoid Welding in Areas of High Residual Stress – This can lead to lamellar tearing.
- Use the Right Size Weld Bead – If you use a weld bead that is too small, it can create insufficient reinforcement. You can also use a larger electrode or increase the size of your welding parameters to correct the problem3.
At the end of each day, or after you complete a major welding project, have your supervisor inspect the weld. They can pick up on any inaccuracies or mistakes you made and allow you time to correct them before the project continues.
Weld Joint Symbols and Interpretation
If you’re new to welding, you might not realize that every weld joint has its own symbol. Symbols are often included on blueprints and CAD drawings to indicate the type of weld joint that should be used. Weld joint symbols are published by the American Welding Society and the American National Standards Institute. All symbols include a horizontal line called a reference line and arrows that show the type of weld it is. For example, a line with arrows pointing to each side represents a tee shape weld. If the symbol includes a small circle, that indicates the weld is to be made all around the joint. If a flag is included in the symbol, that means the weld should be done on site rather than in a shop4.
Are you interested in a welding career? Contact Lincoln Tech Institute today. We offer a training program in Welding Technology that can prepare you for an entry-level career in the field. Our instructors have years of experience in welding and are industry credentialed. You can gain hands-on experience in our labs and take an OSHA-approved safety course before you get out on the job. Fill out the form to learn more.
1 11 Types of Welds You Should Know https://sentin.ai/en/the-11-types-of-welds-you-should-know/ Retrieved September 17, 2024.
2 A Guide to the 5 Basic Types of Weld Joints and Tips for Improving Results https://www.millerwelds.com/resources/article-library/a-guide-to-the-5-basic-types-of-weld-joints-and-tips-for-improving-results Retrieved September 23, 2024.
3 Weld joints tips https://www.arccaptain.com/blogs/article/different-types-of-welds-and-joints Retrieved September 17, 2024.
4 Weld joint symbols https://www.millerwelds.com/resources/article-library/deciphering-weld-symbols Retrieved September 17, 2024.