Welding is one of the craziest things humans have ever figured out, seriously! It’s crazy how versatile it is, whether it’s on land, in space, or even underwater. Welding allows you to bring dissimilar metals together and glue them together at all sorts of angles.
In the world of welding, we typically work with five main types of welding joints that we use all the time.
What is Welding Joint?
A welding joint is basically where two or more pieces of metal or plastic join together. They’re formed by welding these pieces according to a specific shape.
The American Welding Society (AWS) recognizes five types of joints: butt, corner, edge, lap, and tee. Each of these joints can have different configurations where the actual welding happens.
Types of Welding Joint
According to AWS, there are five basic welding joint types that are commonly used in the industry:
- Butt joint welding
- Tee joint welding
- Corner joint welding
- Lap joint welding
- Edge joint welding
When we talk about weld joint design, we’re basically talking about how metal pieces fit together or line up. There are five basic designs for joints: butt joints, lap joints, tee joints, outside corner joints, and edge joints. Each design shows how the different parts of the joint come together.
1. Butt Joint Welding
Butt joint welding is a type of welding joint where two pieces of metal get joined by melting their edges together. To get those edges ready, they’re usually cut or beveled at an angle, making a V-shaped groove.
Once the metal pieces are ready, you put them together so that the beveled edges touch each other. Then comes the fun part! You heat things up, apply some pressure, and melt the metal at the joint, making it fuse together.
Now, there are different ways to do butt joint welding. You’ve got shielded metal arc welding (SMAW), flux-cored arc welding (FCAW), and gas metal arc welding (GMAW). Each of these processes has its own equipment and steps you gotta follow to make sure your weld turns out strong and reliable.
Types of butt weld joints
There are different ways to make butt welds, and each has its own purpose. Let’s take a look at a few examples of butt weld joints:
- Square butt weld: This one’s handy for projects where the metals are 3/16 inches or thinner. It’s a strong joint, but it’s not the best choice if the finished structure will face a lot of shocks or fatigue over time.
- Grooved butt weld: When you’re working with metals thicker than 3/16 inches, the grooved butt joint comes into play. By grooving the metal plates, you give the connection the strength it needs. The extra space allows for more filler material, creating a stronger and more permanent bond.
- V-butt welding: The single V-butt weld is commonly used for plates between 1/4″ and 3/4″ thick while using a tapered angle of around 60 degrees for plates and 75 degrees for pipes. You can prepare the metal using a chamfering machine or a cutting torch. The V-shaped weld seam is a bit pricier to make compared to a square butt joint, and it requires more filler material.
- Double V butt welding: This one’s versatile and works well for a wide range of projects. The cool thing about the double V butt weld is that you can groove metals on both sides, which is great for metals thicker than 3/4 inch. However, you can also use it on thinner plates when you need maximum load resistance.
2. Tee Joint Welding
Tee joint welding is when you join two metal pieces at a 90-degree angle, making a cool T-shaped joint. It’s actually a type of fillet weld and can also happen when you weld a tube or pipe to a base plate. This kind of welding is super common in building steel frames, tanks, and other equipment.
Usually, you don’t need to groove tee joints unless the base metal is thick and the welding on both sides can’t handle the load. One thing to watch out for is a problem called the rupture of lamellae, which happens when the joint is limited. To avoid this, smart welders use a stopper to keep the joint from getting messed up.
3. Corner Joint Welding
When you’re dealing with corner joint welding, it means you got two materials coming together to form an L-shape. This type of joint is handy when you’re building stuff with sheet metal like frames, boxes, and other similar things.
To get this joint done, start by focusing on the outer edges, and then do that same cool zig-zag motion we did for our filleted tee weld.
Now, corner joints can be a bit tricky because you can’t always rest your hand on the material to keep your torch hand steady. So, it’s a good idea to do a practice run along the joint to make sure you’re comfy with the welding. Sometimes, I even clamp a vice grip to another piece of material to create a makeshift handrest.
When it comes to styles for making corner joints, you got some cool options like V-groove, J-groove, U-groove, spot, edge, fillet, corner-flange, bevel-groove, flare-V-groove, and square-groove or butt. So many choices to play around with!
4. Lap Joint Welding
Lap welding joints are like a tweaked version of butt joints. Basically, you take two pieces of metal and overlap them on top of each other. It’s a handy technique when you need to join two pieces of different thicknesses. You can make welds on one side or both sides.
With a lap joint, the edges of the metal overlap so that the joint’s thickness is roughly the same as the combined thickness of the two metal pieces. The overlap distance can vary from a tiny fraction of an inch to several inches or even feet.
Usually, lap welds are created by making a fillet weld along the edge of one plate, connecting it to the other plate’s surface. But there are other ways to weld lap joints, like plug welds, seam welds, and stir welds. You can make welds on one side or both sides of the joint.
Now, there are a couple of things to watch out for with this type of joint. Sometimes, you might encounter issues like lamellar tearing or corrosion because of the overlapping materials. But hey, don’t worry! By using the right techniques and tweaking things as needed, you can prevent those problems.
5. Edge Joint Welding
Edge welding joints are often used when working with sheet metal parts that have flanged edges or when you need to attach one piece to another with a weld. With edge joints, you place the metal surfaces side by side and weld them along the same edge.
When creating an edge joint, you align the metal surfaces so that the edges match up. Sometimes, one or both plates are bent at an angle.
The main goal of a weld joint is to join parts together in a way that distributes the stresses evenly. Welded joints can experience different types of forces like tension, compression, bending, torsion, and shear.
The ability of a welded joint to handle these forces depends on both the joint design and the quality of the weld. Some joint designs can handle certain forces better than others.
The choice of welding process also plays a big role in determining the joint design. Each welding process has its own characteristics that affect how well it performs.
Welding Joint Design
When it comes to welding, the drawings and specs usually tell you exactly which joint design to use for all the welds. Usually, a fancy welding engineer or designer figures out the best joint for the job.
But sometimes, on smaller projects or repair jobs, you gotta make the call on the joint design yourself. It all depends on how the metal pieces fit together.
Figuring out the joints for every weld isn’t always a piece of cake. If you’re the one picking the joint design, you gotta consider a bunch of factors. Stuff like the type and thickness of the metal, the welding position, the welding process, the finished weld properties, and any code requirements.
Choosing the right joint design for a specific weldment means you gotta think about all these different factors. Each factor on its own could lead to a part that’s either impossible to make or doesn’t have enough strength.
For example, a narrower joint angle might save you some filler metal and bring down costs. But if the angle is too small for the welding process you’re using, the weld won’t be strong enough.
A big ol’ weld might be stronger, but it can mess up the part so bad that it becomes useless. The whole point of a welded joint is to join parts together so the whole thing can handle the stress.
Forces acting on a weld create stress, and there are five ways it happens: tension, compression, bending, twisting, and shearing. If the stress is too much, the part can fail. The ability of a welded joint to handle these forces depends on the joint design and the quality of the weld.
Some joints can handle certain forces better than others. So, when you’re picking a weld joint design, you gotta think about stuff like the welding process, how you prep the edges, the dimensions of the joint, the thickness and type of metal, the welding position, any codes or standards, and of course, the cost.
Advantages of Welding Joints
- The welded joint has high strength, sometimes more than the parent metal.
- Different materials can be welded.
- Welding can be performed at any place, with no need for enough clearance.
- They give a smooth appearance and simplicity in design.
- They can be done in any shape and any direction.
- It can be automated.
- Provide a complete rigid joint.
- The addition and modification of existing structures are easy.
Disadvantages of welding Joints
- Members may become distorted due to uneven heating and cooling during welding.
- They are permanent joints, to dismantle we have to break the weld.
- High initial investment
Application of Welding Joints
Welding is widely used for the fabrication of pressure vessels, bridges, building structures, aircraft and space crafts, railway coaches, and general applications in shipbuilding, automobile, electrical, electronic, and defense industries, laying of pipelines, railway tracks, and nuclear installations.
- Fabrication of sheet metal.
- Automobile and aircraft industries.
- Joining ferrous and non-ferrous metals.
- Joining thin metals.
FAQs.
The American Welding Society (AWS) recognizes 5 basic types of weld joints:
1. Butt joint.
2. Corner joint.
3. Edge joint.
4. Lap joint.
5. T-joint.
TIG welding is often considered the strongest weld since it produces extreme heat, and the slow cooling rate results in high tensile strength and ductility. MIG is also an excellent candidate for the strongest type of weld because it can create a strong joint.
A butt joint, or butt weld, is a joint where two pieces of metal are placed together in the same plane, and the side of each metal is joined by welding. A butt weld is the most common type of joint that is used in the fabrication of structures and piping systems.
A butt welding joint is also known as a square grove weld. It’s the easiest and probably the most common weld there is. It consists of two flat pieces that are side by side parallel.
The fillet welds are subjected to tensile stress. The minimum cross-section of the fillet is at the throat. Therefore the failure due to tensile stress occurs at the throat section. Thus the weakest area of the weld is the throat.
