Welcome back! I’m not going to go full-fledged on the Weld Joint Design and Types of Weld Joint in detail. Besides, this article will refresh your knowledge and understanding of the various techniques and practices used in the industry, which include weld joints, design of welds, and types of weld joints.
What is a Weld Joint?
American Welding Society (AWS) says, a joint can be defined as, “The manner in which materials fit together.” in other words, a weld can be defined as “A joint made by melting one or more metals together with the application of pressure, heat, and possibly filler metal.”
For that reason, a “weld joint” is a critical aspect for the strength and stability of the produce. Moreover, to achieve the desired strong weld – the right welding method, the correct equipment, and using the proper techniques play vital roles.
Basically, a weld joint design refers to the way pieces of metal are put together or aligned with each other for the nature of job so as to achieve the desired output – strength and stability.
Firstly, lets physics of welding joints in brief.
What is a Weld Joint Design?
Firstly, the ultimate role of a weld joint design is by far the best outcome on quality and cost. However, various factors to affect the weld joint design as listed below, some that we will be covered elsewhere in the later posts. That includes-
- Types of the Welding joint.
- Stresses on the Weld
- Welding Process
- Edge Preparation
- The Joint Dimensions (Metal Thickness and Type)
- Welding Positions (Plate or Pipe)
- Code Requirements (Welder Skill)
- Welding Symbols
- Location of Welds & Position
Most importantly, as an inspection personnel the basic physics of joint design and the forces that act on the weldment during the welding process to be anticipated and recognized before any weld joint.
What are the Types of Weld Joints?
There are five major weld joint preparations namely, the Butt Joint, Tee Joint, Corner Joint, Lap Joint, and Edge Joint.
Butt Joint Welding
A common type of joint, Butt Joint, is when metal pieces in same plane, usually parallel and with same or different thickness are welded together to form a joint.
When a weld joint design placed (with faces) in tight contact is called a faying surface, that may be required by code, or material, more penetration, appearance or strength characteristics.
Butt joints are the most common type of welding joint used in construction for fabricating structural elements, Tank constructions, and piping systems.
The different types of butt weld joint design are listed below:
- Single bevel
- Double bevel
- Single J
- Double J
- Single V
- Double V
- Single U
- Double U grooves
When it comes to butt joints, commonly occurring defects may include burn through, porosity, cracking or incomplete penetration. However, avoid them by modifying the welding variables.
Tee Joint Welding
The tee joints are, understandably, typical joints found in the structural, and tank bottom weldments. Tee joints are when the work pieces are placed with one edge is placed on another member giving a 90 Deg or more or less perpendicular look as a “T” shape.
Tee joints are basically fillet welds (either plate or pipe). Rarely groove welds, until design mandates. Effective penetration to the root is the key and the below weld designs may be considered based on the nature of job.
- Plug weld
- Slot weld
- Bevel-groove weld
- Fillet weld
- J-groove weld
- Melt-through weld
- Flare-bevel-groove weld
Lamellar tears are a defect that happens due to joint restrictions on the tee joints. Since the welding is restricted, a stopper may be required to avoid joint deformation and resulting in the lamellar tear defects in welds.
Corner Joint Welding
These are similar to Tee Weld Joint, however, the position of metal is on the their corner (open or closed) edges can meet at the corner evenly or they can overlap forming an ‘L’ shape.
Besides, their most common application in the sheet metal industry for frames or box type designs. It basically fits either it forms a V-groove or a square butt joint.
Therefore, the welding styles used for creating corner joints include V-groove, J-groove, U-groove, spot, edge, fillet, corner-flange, bevel-groove, flare-V-groove and square-groove or butt.
Lap Joint Welding
Lap welding joints is a modified version of the butt joint such that the thickness of the joint is approximately equal to the combined thickness of both pieces of metal.
In other words, they are formed when two pieces of metal are placed in an overlapping pattern on top of each other, where welding is possible on either of sides. Some examples of this would be plug welds and seam welds.
Lap joints are mostly applied to sheet metals, and of less thickness. It is recommended to follow right techniques to avoid a possibility lamellar tearing defect as with the T-joint, or a corrosion due to overlapping materials.
Edge Joint Welding
The metal surfaces are placed together so that the edges are even in an edge joint. Also, possible to form one or both plates by bending them at an angle.
For that reason, the edge joints are usually welded on only one side.
The types applicable for edge joints:
More prone to corrosion due to this overlapping arrangement. There are other probable defects like inclusions, lack of fusion, and porosity, that can occur.
Weld Joint Stresses
The stresses are widely distributed in a weld. As a result, either tensile, compression, bending or other stresses may act on the material. The ability of a welded joint to resist these forces is dependent on both the design and the integrity of the welds.
Joint design is the most important part of welding. The selection of the joint design can be affected by the welding process that will be used. The performance of each welding process can be affected by its characteristics.
Different welding processes have their own limitations in joint design, so it is important to choose the right welding process for your application. Some processes are easily used in any position; others may be restricted to one or more positions. For example, a square butt joint can be made in very thick plates using either electroslag or electrogas welding, but not many other processes can be used on such a joint design. The welding process’s characteristics affect its performance. Joint design and the weld process plays a vital role in metal deposition, travel rate, penetration, and heat input applied on the weld joint.
Understanding Different Welding Joint Types
Types of Weld Joint Design
Face Welding (Face Welds)
- Face welding joints are usually used for small jobs
- They use very thin filler metal, which can be hard to weld
- The metal used is thinner than the base metal, so it can be harder to weld
Butt Welding (Butt Welds)
It’s easier to perform than other types of welding
- You can get a good quality weld with a small amount of filler
- It’s the most common welding joint
- It’s easy to make, even for beginners
Flange Welding (Flange Welds)
- Flanges are used for connecting two pieces of equipment, like pipes or tanks.
Welding Girth (Girth Welds)
- These joints are used for joining pieces of pipe or tubing.
Other Welding Joint Types
You may also find weld joints for other purposes, like a pipe fitting or pipe hanger.
There are more, but we’ll end here for now.
In general do learn to interpret all aspects of weld physics. Therefore, the more we understand, we get the perfect weld joint outcome whereby over welds, under-welds, defects and other undesirable issues can be avoided.
Do let me know how you would simplify the term “weld joint design” from your point of view.