TYPES OF WELDING JOINTS
A weld joint refers to how the parts to be joined are assembled prior to welding. There are five basic types of joints used in welding which are Butt, Lap, Corner, T & Edge.
The metal to be joined is called the base metal. If the part to be welded is not metal, it is called base material. It is also known as a workpiece or work. The edge of base metals are often machined, sheared, gouged, flame cut, or bent to prepare them for welding. Weld joint design and metal thickness usually determine how the joint is prepared. Generally, the weld joint design is determined by an engineer.
Understanding Different Welding Joint Types
The term “weld joint design” refers to the way pieces of metal are put together or aligned with each other. Each joint’s design affects the quality and cost of the completed weld. Selecting the most appropriate joint design for a welding job requires special attention and skill.
There are five basic welding joint types commonly used in the industry, according to the AWS:
- Butt joint welding
- Tee joint welding
- Corner joint welding
- Lap joint welding
- Edge joint welding
BUTT JOINT
Butt joint winding is a type of winding technique used in the manufacture of electrical components, such as transformers and inductors. In a butt joint winding, two or more turns of wire are laid adjacent to each other with no overlap, creating a straight, linear joint. The wire ends are then soldered together to form a continuous electrical path.
This type of winding is used in applications where a compact design is desired, as it reduces the overall size of the component compared to other winding techniques, such as overlapping layer winding. Butt joint windings are also used in applications where a high number of turns is required, as it is possible to achieve a high packing density with this technique.
Butt welds are made in a variety of ways, and each one serves a different purpose. Varying factors include the shape of the groove, layering, and width of the gap. Listed below are some typical examples of butt weld joints.
- Square
- Single bevel
- Double bevel
- Single J
- Double J
- Single V
- Double V
- Single U
- Double U grooves
Reasons for preparing the faying surfaces for welding include the following:
- Codes and standards
- Metals
- Deeper weld penetration
- Smooth appearance
- Increased strength
- Joins two members that meet at their edges on the same plane.
- Used in applications where a smooth weld face is required.
- Fillet or groove welded; groove welding requires added expertise and expense.
- Improper design/welding risks distortion and residual stresses.
T-JOINT
Tee joint welding is a type of welding joint that is used to join two metal components at a right angle to each other, creating a T-shaped connection. The Tee joint is commonly used in the fabrication of structures, such as frames, and in the manufacture of equipment, such as pipes and ducts.
In Tee joint welding, the two components are positioned at a right angle to each other and are then joined by welding along the joint line. The welding can be performed using various welding techniques, including arc welding, gas welding, or resistance welding, depending on the properties of the metal and the requirements of the application.
Tee joint welding provides several advantages, including high strength, improved stability, and increased rigidity. However, it is important to consider the welding process carefully, as improper welding can result in weak spots or cracks that can affect the overall integrity of the joint. Additionally, it is essential to properly prepare the metal surfaces to be joined, including cleaning and removing any contaminants or oxidation, to ensure a strong, stable weld.
With this type of weld, it’s important to always ensure there is effective penetration into the roof of the weld. There are a handful of welding styles that can be used to create a tee joint:
- Plug weld
- Slot weld
- Bevel-groove weld
- Fillet weld
- J-groove weld
- Melt-through weld
- Flare-bevel-groove weld
- Joins two members that meet at a T-shaped angle
- Good mechanical properties, especially when welded from both sides
- Easily welded with little or no joint preparation
- Usually fillet welded, although J-grooves are possible
LAP JOINT
Lap welding joints are essentially a modified version of the butt joint. They are formed when two pieces of metal are placed in an overlapping pattern on top of each other. They are most commonly used to joint two pieces with differing thicknesses together. Welds can be made on one or both sides.
- Joins two members having overlapping surfaces
- Good mechanical properties, especially when welded from both sides
- Usually, fillet welded
- Thicker material requires more overlap
CORNER JOINT
Corner joint welding is a welding technique used to join two metal parts at a 90-degree angle, forming a corner joint. This type of joint is commonly used in metal fabrication, construction, and repair work. The most common welding processes used for corner joint welding are Gas Tungsten Arc Welding (GTAW), Gas Metal Arc Welding (GMAW), and Flux Cored Arc Welding (FCAW). The choice of welding process and technique depends on various factors such as the thickness and type of metal, the desired weld appearance, and the accessibility of the joint.
- Joins two members that meet at an angle
- Two main types: open-corner and closed corner
- Easily welded with little or no joint preparation
- Increase travel speed on light-gauge material to avoid burn-through
EDGE JOINT
Lap joint welding is a welding technique used to join two metal parts by overlapping them, forming a lap joint. This type of joint is commonly used in metal fabrication and repair work. The most common welding processes used for lap joint welding are Gas Tungsten Arc Welding (GTAW), Gas Metal Arc Welding (GMAW), and Flux Cored Arc Welding (FCAW). The choice of welding process and technique depends on various factors such as the thickness and type of metal, the desired weld appearance, and the accessibility of the joint. To ensure a strong and effective lap joint, the edges of the metal parts should be beveled, and the weld bead should be placed in the groove between the overlapping parts.
- Joins two parallel, or nearly parallel, members
- Not recommended if either member will be subject to impact or high stresses
- Square groove is most common, but other groove configurations are possible
- Very deep penetration is impossible
