A Guide To 5 Basic Types of Weld Joints

A Guide To 5 Basic Types of Weld Joints

5 Basic Types of Weld Joints and Helpful Tips for Great Results

Joint design determines which type of weld you should attempt. There are several types of weld joints, and each is suitable for a specific application. In this article, we will discuss the five basic types of weld joints. We will also cover some useful tips that will help you achieve high-quality weld.

Weld Joint Design

A weld joint forms when two or more materials are joined by the welding process with or without the addition of filler material. A weld joint can be created from similar or dissimilar metals.

There are several factors that contribute to creating a good weld. It is critical to understand the joint design to produce a high-quality weld. The weld joint design determines which type of weld to produce to meet the quality standards of the application.

Here are some examples of joint design and the type of weld required:

Joint Design Type of Weld
Butt Joint Groove Weld
T-Joint Fillet Weld
Corner Joint Groove or Fillet Weld

5 Basic Types of Weld Joint

The American Welding Society (AWS) recognizes 5 basic types of weld joints:

  • Butt joint
  • Lap joint
  • Edge joint
  • Tee joint
  • Corner joint

Butt Joint

A butt joint is formed when two workpieces are placed in the same plane and the side of each workpiece is joined by welding. This is the most common type of welding joint used in the manufacturing of pipelines and structures. Butt joints are easy to prepare for welding. There are different variations of this weld joint, and each serves a different purpose.

Examples of butt weld joints include:

  • Single U
  • Double U grooves
  • Single V
  • Double V
  • Single bevel
  • Double bevel
  • Square

During the welding process, the area of the metal surface that is melted is referred to as the faying surface. Before welding, the faying surface is shaped to enhance weld strength. This process is known as edge preparation. Both sides of the butt joint may have the same edge preparation, or each side can be prepared differently.

Edge preparation, or shaping of the faying surface for welding, is conducted to allow deeper penetration, increased strength, and a smooth appearance. It also allows the weld to adhere to specific codes and standards. Proper butt weld preparation is determined by numerous factors, including the shape of the groove, width of the gap, and layering. The wider the groove is, the more welding it requires to make the joint. For thin sections, full penetration welds are possible with a square butt joint. For thicker sections, full penetration welds are only possible with the use of a groove. With thicker metals, joint design plays a crucial role to ensure a sound weld.

The application and material thickness determine if the edges of a butt joint should be beveled or square. While beveled edges create a stronger weld, they require more weld deposit and are more time-consuming.

Some of the common defects that occur in butt joints include porosity, burn through, incomplete penetration, and cracking. However, these defects can be prevented by modification of the welding variables.

Lap Joint

In a lap joint, the surfaces of the two workpieces overlap. The weld is formed where the surfaces intersect. The thickness of the workpiece determines the area of overlap. The thicker the workpiece, the more overlap is required.

Lap joints have good mechanical properties. When welding a lap joint, it is important to ensure that there are no gaps between the two workpieces. For welding thinner materials like sheet metal, consider reducing the amperage and increasing travel speed to avoid any distortion and burn-through.

There may be times when you need to choose between a butt joint or a lap joint. Lap joints ensure more strength in high stress areas. However, lap joints do not result in a flush contour, making them more noticeable than butt welds.

Edge Joint

In edge joints, the fit-up of the workpieces leaves the edges nearly parallel or parallel to one another. These types of joints are used where the workpieces are not subject to stress. There are several types of edge joints based on how the edges are prepared for welding. Some of the applications for edge joints include:


  • U-groove
  • V-groove
  • Bevel-groove
  • Corner-groove
  • Square-groove

Corner Joint

A corner joint is formed when two workpieces are welded from 90° to an L shape. This type of joint is easy to assemble and requires little edge preparation, if any. There are two types of corner joints – open corner joint and closed corner joint. In a closed corner joint, the edge of one workpiece lies flush against the edge of another workpiece. In an open corner joint, the two edges of the workpiece join at the corners. There is an opening where the thickness of each workpiece is visible. Corner joints are mostly used for projects that require a square frame.

You can choose between an open corner joint and a closed corner joint depending on the thickness of the material and the required strength for your application. When welding an open corner joint on thinner material, consider increasing the travel speed to prevent any burn-through. Open corner joints create a V shape. Based on the material thickness, this type of joint may require more weld deposit. When welding a closed corner joint, you need to grind the weld face. This helps create a smooth transition from the weld to the base material.

When creating a corner joint make sure to properly fit the workpieces. Based on how the joint is prepared, there are possibilities for distortion post welding. To prevent any distortion, create a fixture that holds the workpiece in place.

Tee Joint

A Tee joint forms when two workpieces join at 90°. In this type of joint, the edge of one workpiece is welded to the center of the flat surface of another workpiece to take the shape of a T. A pipe or tube welded to a base plate can also form a Tee joint. This type of joint has high mechanical strength, especially when welded from both sides. Tee joints are used in many fabrication applications including tubing, structural steel, and equipment.

When the right parameters and techniques are used, Tee joints are easy to weld and require less joint preparation. When preparing a Tee joint, it is crucial to weld on the side of the joint that would be subjected to any type of stress. The roof of the weld must have effective penetration. Any load or impact from the opposite side of the joint could cause the failure of the weld. You can avoid this by welding on both sides to achieve maximum strength. Tee joints are easy to weld in horizontal, flat, vertical, and overhead positions.

When welding a 90° Tee joint, split the difference with a 45° work angle to ensure deep penetration on both workpieces. When welding dissimilar metal thicknesses, you need to focus the weld on the thicker material. Lamellar tearing, which occurs due to restriction within the joint, is one of the common defects observed in Tee joints. To prevent any joint deformities welders often place a stopper.

Which Weld Joint is Right for Your Application?

There are five types of weld joint design. The specific weld joint you need to choose depends on the application and required strength. Therefore, it is crucial to understand the differences when selecting the best joint design for your project. This knowledge can help ensure you use the right weld joint and technique for your welding project.