Types of Welds and Weld Joint with their Welding Symbols

Types of welds and joints

There are many different types of welds and joints, each with its own weld joint configuration and specially assigned welding symbol as per AWS A2.4 or ISO 14555.

The most common type of weld is the butt weld, which joins two pieces of metal at their ends. A lap joint weld joins two pieces of metal that overlap each other, while a T-joint weld joins two pieces of metal at right angles to each other.

Other types of welds include the corner weld, the edge weld, and the slot weld. Each type of weld has its own specific symbol that is used to indicate how the parts should be positioned during welding.

Main Type of Welding Joint

There are various types of weld joints with varied weld joint configuration, each with their own welding symbols. The most common are:

  • Butt Joint
  • T-Joint
  • Lap Joint
  • Corner Joint
  • Edge Joint
  • Flange Joint
  • Flare Joint
  • Cruciform Joint

Butt weld

A butt weld is the simplest type of weld, and is made by joining two pieces of metal together at their flat ends. The two pieces are placed flush against each other, and welded together. Butt welds are mainly used for high strength & stress areas.

Single-V-groove-weld
A Single V-Groove Butt Weld

There are Four main types of butt welds:

  1. Square butt weld: without any weld bevel on joining member
  2. Bevel butt Joint: Bevel on one joining member, either single side or both side of the joining member.
  3. Groove Weld butt Joint: Bevel prepared on both joining member. Different types of groove weld as single side V-Groove, Double side V-Groove, J groove, U groove weld, etc.
  4. Flare Butt Joint: Special type of groove weld, where one or both members are round in shape.
groove-welds
Types of Butt Groove Welds

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Lap joint

A lap joint is a type of welded joint in which two pieces of metal are lapped together and then welded. The overlapping edges of the two pieces are usually welded using a Fillet Weld. Lap joints are usually made on small thickness to increase strength of weld joint.

Lap_joint
A Lap joint Example

Lap joints are used in a variety of applications, including electrical junction boxes, automotive panels, and aircraft components. They offer several advantages over other types of welds, such as improved strength and ease in making.

T-joint

T-joints are one of the most commonly used welds in industry. They are made by joining two pieces of metal at a 90 degree angle. Fillet weld is the most common example of a T-Joint. Although, T-Joint can be made using groove weld.

Fillet-weld
a T-Joint in a plate

T-joints can be used to join both thick and thin pieces of metal, and are often used in the construction of buildings and bridges. T-Joint will groove are used to make full penetration T-Joints, also called HV welds for high loading applications where a butt weld is not feasible.

Fillet weld

A fillet weld is a type of welding joint in which two pieces of metal are joined together at an angle of 90 degrees.

The strength of a fillet weld is determined by its size (throat thickness) and the part thickness of metal being joined.

The size of the fillet (the length of each side of the triangle) will determine the strength of the weld.

Concave-convex-mitre-fillet-weld
Example of Fillet Weld and Different Fillet Weld Types

Types of Fillet Weld

Fillet welds are the most common type of weld used in both construction and manufacturing, but there are actually three different types of fillet welds are:

  • Convex Fillet,
  • Concave Fillet, and
  • Metre Fillet.

A convex fillet weld is created when the weld bead has a rounded or protruding profile. This type of weld is typically used when aesthetic appeal is important, as it creates a smooth, finished look.

Concave fillet welds are the opposite of convex; they have an indented or depressed profile. These types of welds are often used in structural applications where strength is key, especially fatigue loading.

Metre fillet weld has flat surface finish and usually achieved by grinding. Metre fillet welds are not common in use.

Corner joint

A corner joint is created when two pieces of metal are joined at a 90 degree angle. This type of joint is often used for framing or in construction. A welder will use a welding symbol to indicate which side of the joint should be welded first.

Corner-weld-joint-types
Different Types of Corner weld

Read more: Corner Joint Welding- The Basics You Need to Know

Edge joint

Edge joints are created when two pieces of metal are placed side-by-side and welded together. The weld is between the edges of 2 or more parallel or nearly parallel plates.

edge-joint types
Different types of Edge Joints

Edge joints are typically used when joining sheet metal or thin plates. When two thick plates are to be joined, an edge joint is not recommended as it would not provide sufficient strength. In these cases, a butt joint would be a better option.

Slot weld

A slot weld is a type of groove joint that is made by welding along the edges of a slot that has been cut into one of the pieces to be joined. The other piece is without any cut. The two pieces are brought together to overlap each other to form a pocket via the cut slot that is filled with welding.

Slot weld is similar to plug weld but in slot welds the cut is elongated instead of round hole as shown in below picture.

plug weld vs slot weld 1 Types of Welds and Weld Joint with their Welding Symbols
Examples of Plug Weld & Slot weld

To make a slot weld, the welder first uses a torch or plasma cutter to cut a elongated groove or slot into one of the pieces to be joined. This slot is filled with welding to form a slot weld.

Plug Weld

A plug weld is a type of slot weld but having round hole instead of elongated slot hole, which is defined as a weld made between two overlapping metal surfaces.

Plug welds are often used to attach patch plate to add thickness to existing plate. In a plug weld, the hole is filled completely for full depth and hence plug welds are not a fillet weld.

There are several benefits to using plug welds. They create a stronger joint than other types of spot welds, and they can be used on thicker materials. Additionally, plug welds can be made quickly and easily with automated welding equipment.

Flare Groove Weld

Flare groove welds are widely used in the construction industry because they offer high strength and durability. A flare bevel Groove Weld is a type of weld where a groove is formed between a joint member with a curved surface and another with a planar surface.

The main types of Flare weld are:

  • Flare Bevel Weld; Single Flare & Double Flare
  • Flare V-Groove Weld; Single Flare-V and Double Flare-V

So, for a flare bevel groove to take place, one joining member needs to be a tubular shape. For example, a weld formed between a pipe and plate placed horizontally to each other as shown in the below figure.

types-of-flare-bevel Weld Joints
Different Types of Flare Weld

Read More: How to measure a Flare V groove weld?

Spot weld

A spot weld is a type of weld that joins two pieces of overlapping metal together by fusing them at localized points at faying surfaces. Spot welding is mainly used for sheet metal welding applications.

Spot welding is commonly used in the automotive industry to join panels and other components together. The process is relatively quick and easy, and it results in a strong bond between the two pieces of metal.

spot weld Types of Welds and Weld Joint with their Welding Symbols
A spot weld with its welding symbol

To create a spot weld, an electrode is placed on each side of the two pieces of metal to be joined. An electric current is then passed through the electrodes, which heats the metal and causes it to fuse together at the point of contact in a circular weld cross section. The resulting joint is typically very strong and can withstand a lot of force.

Spot welding is an efficient way to join two pieces of metal together, and it results in a strong bond that can withstand a lot of force.

Surfacing Weld

Surfacing welds are used to build up metal that has been worn down or damaged. A surfacing weld is done by depositing a layer of welding material on the surface of the metal.

surface-weld symbol
Example of Surfacing Weld with its Welding Symbol

This type of weld is also used to add strength to a metal that is not strong enough on its own. Surfacing welds can be done with any type of welding process, but they are most commonly done with arc welding processes.

Surfacing weld is also called Weld buttering or Weld Build up (WBU) in industries.

Projection Welds

A projection weld is a type of spot weld that is made by projecting or embossing a raised metal area onto the work piece under heavy pressure. The embossed area is then melted and the two pieces of metal are joined together. Projection welding is often used to join thin sheets of metal together, such as in the automotive industry.

projection weld joint 1 Types of Welds and Weld Joint with their Welding Symbols
Projection weld joint process

The advantage of projection welding over other types of spot welding is that it can be used to weld large areas quickly and efficiently. Additionally, projection welding can be used to create strong welds that are less likely to leak or break.

There are several things to keep in mind when projection welding, such as the size and shape of the projections, the amount of current, and the speed at which the electrode moves. By following these guidelines, it is possible to create strong, high-quality welds.

Seam Weld

A seam weld is a type of welding that joins two pieces of metal together by fusing them along their seam by overlapping each other. Seam welding is often used in the automotive industry to join together panels of sheet metal. The advantage of using a seam weld is that seam weld is faster and does not require any filler wire.

seam weld Types of Welds and Weld Joint with their Welding Symbols
Seam weld joint

Stud Weld

A stud weld is a type of welding where a metal rod, or stud, is joined to another piece of metal. The stud is first attached to a stud welding gun. Then, an arc is created between the gun with stud and base metal, which melts the stud end and metals to join them together.

Stud weld Types of Welds and Weld Joint with their Welding Symbols
a stud weld

Stud welding is often used in construction and manufacturing, as it can create strong joints between two pieces of metal quickly and easily. This type of welding is also relatively simple to do, which makes it a good choice for many projects.

There are two main types of stud welds: arc welds and resistance welds. Arc welds are created using an electric arc, while resistance welds use heat to melt the metals together. Both types of welds can be completed using either automatic or manual equipment.

Upset Weld

Upset weld is a type of weld that is created using resistance welding process. The pressure and resistance is applied between two abutting surfaces to create heat and produce a welding joint.

Upset welds are strong and can be used on thick materials but requires two material having flat surface.


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