Exploring Different Types of Welding Joints

Glancing into the World of Weld Joints and Types  

The weld joint design is how pieces of metal are aligned with each other. Each joint’s design impacts the quality and cost of the final weld.

The welding applications are numerous, and different tasks require different welding kinds and joints. There are five types of welding joints, each to meet the requirements and suitability of different applications. 
1.    Butt joint
2.    Lap joint
3.    Edge joint
4.    Tee joint
5.    Corner joint

Butt Joint Weld 

A butt joint weld is one of the most common and simplest kinds of weld and is also known as square groove weld. It is made when workpieces are put in parallel, and the side of each workpiece is joined by welding. As a cost-effective solution, it is extensively used to create pipelines, structures, valves, fittings, flanges, and other equipment. The different weld variations of butt joints, serving distinct purposes, could be either of the following. 

•    Single/ Double U
•    Single/ Double V
•    Single/ Double Bevel
•    Square

During the welding process, the metal’s area surface, which is melted, is called the faying surface. Before welding, this faying surface is shaped to enhance the strength of the weld. This process is known as edge preparation. In the Butt weld joint, both sides could have the same edge preparation or could differ depending on the application type. The edge preparation process helps to allow deeper penetration, a smooth appearance, and increased strength. Several factors, like the width of the gap between metals, the shape of the groove, layering, etc, could depict the weld preparation. The wider the groove is, the more welding might be required to make the joint. For thicker sections, full penetration is only possible with the use of a groove, and for thinner sections, it could be possible with the help of a square butt joint. The commonest faults that could appear in these joints are cracking, burns through, porosity, and inadequate penetration. These faults can be avoided by changing welding factors like groove shape, gap width, and layering.

Lap Joint Weld

Lap joints are formed when two workpieces are stacked in an overlapping pattern on top of each other. The weld is made where the surfaces intersect, and the thickness of the workpieces determines the overlap area. The thicker the workpiece would be, the more overlap would be required. 

Lap joints are known to have robust mechanical properties. Ensuring no gaps between workpieces is essential when creating a Lap joint weld. They are usually used to weld thicker materials. Consider increasing the travel speed and cutting down the amperage for thinner materials to avoid any burn through or distortion during welding. There could be situations where one needs to give preference to whether to opt for a lap joint or butt joint. In high stress areas, Lap joints ensure more strength. Although, in a flush contour, lap joints do not show much effective results as of butt joints.  
 
These joints are mainly used in structural frames for automotive, picture frames, cabinets, tabling, etc. The potential faults that could happen are corrosion or lamellar tearing due to overlapping materials. However, if required, it can be avoided by using proper techniques and changing variables such as volts and amps. 

Edge Joint Weld

In Edge joint welding, the workpieces are joined together and welded at an edge point. To achieve this, one or both plates need to be bended at an angle, and the purpose is to bind pieces together and distribute stresses. Depending on how the edges are prepared for welding, there could be many types of edge joint, and some of them are as follows. 

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

These are used mainly for joining edges of mufflers, sheet metals, and other low-pressure and low-stress applications. Different forces can cause stress in weld joints. It could be Torsion, Tensile, Bending, Compression, or Shear forces. The welding type that will be used will significantly impact the joint design that will be chosen. Each welding type has its features, influencing how well it performs during the process. The welds used on different collaborative designs could be highly impacted due to various aspects like deposition rate, rate of travel, heat input, penetration, etc. 

Tee Joint Weld

A Tee joint weld form is made when two workpieces meet at a 90-degree angle. The edges of the components or the plate make a ‘T’ shape when joined in the middle. A tube or pipe welded to a base plate can also make a Tee joint. When welded from both sides, this weld joint has good mechanical strength. 

When the technique and parameters are correct, Tee joints are easy to weld and require less joint preparation. While creating the joint, it is essential to weld at the side subjected to any form of stress. The weld roof must get apt penetration, as any load or impact from the other end of the joint could lead to failure. Welding on both sides can help avoid this situation and achieve maximum strength. Also, they are easy to weld in flat, horizontal, vertical and overhead positions. The common fault with these joint welds is Lamellar tearing due to the joint’s limitation. To prevent joint distortions, welders need to insert a stopper. Tee joints are used in several fabrication applications like structural steel, tubing, sheet metals, and equipment. 

Corner Joint Weld

Corner joints are made when two workpieces are joined and welded from 90° to an L shape. They are easy to create and require little edge preparation, if any. Usually, there are two kinds of corner joints:

1.    Open Corner Joint – Two edges of the workpiece join at the corners
2.    Closed Corner Joint -  Edge of one workpiece lies flush against the edge of another workpiece 

Corner joints are mainly used for those projects requiring a square frame, construction and automotive industries, pressure vessels, storage tanks, etc. Depending on the required strength of the job and the thickness of the material, one can choose between the open or closed corner joint. If you use an open corner joint on thinner material, increase the travel speed to prevent any burn through in the weld. Open corner joints make a V-shape. Based on the thickness of the material, it may require more weld deposit. While welding a closed corner joint, it is a must to grind the weld face as it assists in creating a smooth transition from the weld to the base material. Also, keep the workpieces adequately fitted in corner joints to prevent any distortions.  

Conclusion:

Different aspects contribute to creating a good weld, and it is critically significant to understand the joint design to make a superior quality weld. The weld joint design depicts which kind of weld needs to be produced to meet the project's quality standards. For example, the list below shows the type of joint design and weld required for the job. 

Weld Joint Design	Type of Weld
Butt Joint	Groove Weld
Tee Joint	Fillet Weld
Corner Joint	Groove or Fillet Weld
Lap Joint	Fillet Weld
Edge Joint	Groove Weld

In all, selecting the right weld joint from the above information depends much on the strength required for the job, the space and accessibility of the weld, and the positioning of the parts and equipment.  Kindly calculate the approximate load-bearing requirements of every part to select the right weld joint. It is necessary to understand the different joint designs among welders as it enables them to learn of varied forces that could be applied to a weldment in the field. Integrating the knowledge into the right joint design could help achieve not only weld integrity and quality but also prevent structural failures down the line.