Types of Welding Joints (When and How They are Used for)

A welding joint is an edge having two or more pieces of metal joined together. According to the American Welding Society, there are five generalized types of welding joints. They are the Butt joint, Corner joint, Edge joint, Lap joint, and Tee joint. Hence, depending on the joint the welder has to choose an appropriate welding joint process.
Different types of welding processes are made to stand up to the needs and forces of an individual’s requirements.

Similarly, various types of joint techniques are also used namely routing, stamping, shearing, casting, forging machining, filing, plasma arc cutting, oxyacetylene cutting.

Tee-Welding Joint

A Tee-Joint is formed when two bars of sheet or any metal surfaces are joined perpendicular (90 deg) to each other. This forms a T-shape. It can be performed by Extrusion Welding also. The extrusion is welded to both sides of the metal pieces. A Tee joint can be performed using the following welding styles:

A Tee joint is commonly used around various construction projects and other structures where a metal part is attached to the base. It is widely applicable when the pipe is welded onto the base of metal, attaching tin plates and various other structural and machinery applications.

Lap-Welding Joint

Lap welding joints are most often used to join two pieces of different thicknesses of metals together. Here, one metal is placed horizontally on top of the other in such a way that the starting edge of one piece is placed at the center of the other one. This joint is widely used in electron and laser beams. It can be made using the following welding processes:

This is considered one of the best and most reliable welding processes as there is a surplus amount of surface area between the welds. The name “lap joint” is coined from the word “Overlap”. These joints are pretty much smooth, to begin with, and it will be a great option to begin welding with. It adds extra strength to the project we do. If there is a distortion to the plates, it will be at the ends, as they are the weakest points.

Edge-Welding Joint

Edge welding joints are made where any metal plate has a flanging edge or we need to attach any new adjacent metal piece to it. The parts in the edge joint are parallel with at least one of their edges in common and the joint is made at the common edges. Filler metal is added to melt and fuse the metal’s edges completely. Welding styles used to create edge joints are as follows:

We require an edge thickness up to a range of 19.05mm. However, this process of welding isn’t quite strong enough to withstand heavy loads as the weld doesn’t fully penetrate into the thickness of the joint. To reinforce the plate, the welder can add some filler metal to it.

Corner-Welding Joint

Corner-welding joints are mostly used in the sheet-welding industries. Here, the joint forms at L with the two pieces being places at right angles to each other. Hence, it is commonly used in boxes, frames, and similar fabrications. Welding styles used to create this welding joint are:

The metal pieces in a corner joint form a right angle (90 deg). It is also the type of joint that gets replaced often due to the pressure and stress most corners of the structures bear. It is also quite common in the welding industries.

Butt-Welding Joint

A butt-welding joint is also known as a square groove weld. It basically consists of two blocks attached parallel to one another horizontally. Welding styles used to create Butt joints are:

Square Butt Joints

The square-groove is a butt welding is one type where the metal pieces are welded being parallel to one another horizontally. This joint is simple to prepare, economical, and provides immense strength. The joint type is common with gas and arc welding. Only a metal having up to 4.5mm thickness is usually used for square butt joints. The thickness of the metal ranges from 6.35 mm.

V-groove Joints

Single V-butt joints are just like a bevel joint, but instead of one side, both sides of the weld joint are beveled together on a single edge. Heavy warping and pressure can be neglected by welding a double V-joint. The thickness of the metal ranges from19.05 mm.

U-groove Joints

So, single U-butt welds have both edges of the weld surface shaped like a J, but once they come together, they form a U-shape. These are the most expensive edge to prepare and weld. They form on thick bases of metals. The thickness of the metal ranges from19.05 mm.

J-groove Joints

A single J-butt weld consists of a single J-shaped metal welded to a square piece of metal with some filler material. A J-groove is formed either with special cutting machinery or by grinding the joint edge in the form of a J-shaped joint. The thickness of the metal ranges from 12.70 to –19.05 mm.

Cruciform

A cruciform joint is a specific joint in which four different areas can be created by welding three plates of metal at right angles on a single joint. Crucifer joints suffer from fatigue when subjected to heavy loads continuously.

Types of Weld Beads

1. Fillet Welds

A fillet weld joins two surfaces at approximately right angles. It has several types under it namely:

2. SocketWeld

A socket weld is a style in which a pipe is inserted into any attachment area of a valve, fitting, or flange. Socket weld fittings are used for small pipe fittings. Pipe diameter sizes here vary from 1mm-2mm.

3. Slot Weld

A spot weld is a type of weld between two metals where the metal is elongated and it’s extended to the other metal piece through the elongated hole of the first metal to weld them together. The hole is either completely or partially filled.

4. Groove Weld

The second most popular type of welding is the groove weld. There are 7 basic types of groove welds where the type of weld used will determine the manner in which the seam, joint, or surface is prepared. According to the AWS (American Welding Society), a groove weld is a weld on a workpiece surface, between two workpieces or edges. There are 4 positions for a fillet or groove weld. They are:

Watch Video: Good Weld Bead vs Bad Weld Bead

Welding Symbols

Welding symbols provide the means of placing complete welding information via drawings. This is a method predominately used in the United States. Welding symbols are highly essential to convey any kind of information or outline of the project pictorially to the construction workers and other workmen.

Hence, we can see that these kinds of diagrammatic representations can help simplify the language barrier and explanation of details from the designer to the builder.

Arrow

The arrow that you see in the diagram is the direction and the location pointing to where the weld is required. In the end, there is a tail at the opposite end of the reference line.

Weld Symbol

Dangling from the middle of the reference line, you’ll see a geometric shape or two parallel lines. This is known as the ‘Weld symbol’. The three weld drawings below are a square, fillet, and groove-weld respectively.

Dimensions and Angles

Numbers are definitely a part of a welding specification. The width, depth, root opening, and length of a weld and its angle of the bevel will be represented quite easily.

Sean Coby

Sean Coby is a welder par excellence and well respected among the welding community in Woodbridge, VA. He prides himself to be the fabricator and mechanic in the automotive/ diesel industry for the past more than eight years now. As the chief editor of his https://weldinginfocenter.com, he shares his experience to be safe during welding and to take proactive steps for becoming a successful welder like him.