Welding Joints

In the world of metalworking and engineering, the tasks at hand will always appear simpler than they really are, no matter how big or small. A tradesperson can spend a lifetime adding to his/her skill set and when it comes to the discussion of welding, the learning will likely never end. Today we will try to add some new and/or improved knowledge to your brain bank by investigating together with the 5 most commonly utilized welding joints in an easy-to-read text.

Welding Joints

Butt Joint

This joint is simple in preparation and when welded correctly, it is unbelievably strong. Two pieces of metal are stacked together horizontally flush, then 1 or 2 sides of the joint are fully welded, depending on the job’s requirements.  Butt joints are useful to use on a range of material thicknesses ranging from 0.5mm to 20mm+ metals, although it is important to note that when the joint is utilized with very light or heavy materials, different processes of preparation and welding are required.

Discussing optimal welding joints for beginners, the Butt Joint is perfect as it is not difficult to prepare and is straightforward with its purpose. Saying this, it is definitely not just limited to beginners and is made use of frequently on anything from tractor repairs to high-level structural projects alongside being usable on all metal types. There are different variations to the Butt Joint which we will discuss below.

Single Square

The most basic and common version of the butt joint and very economical to prepare however, it is limited by material thickness without a prepared bevel/angle.

Single Bevel

Another easy joint where a single-sided angle is prepared on one of the two metals. This is with the purpose of allowing deeper weld penetration and increased strength.

Double Bevel

Two 45-degree angles are prepared to create a pointed nose on one of the metals. This beveled piece of metal is likely to be under more stress than the other piece so increased weld penetration and strength are necessary.


Both of the metal pieces are prepared with a matching single-sided 45-degree bevel which allows for full weld penetration. Depending on the material thickness, multiple welds with a root run can be laid for increased joint life expectancy.


Both metals are prepared with matching double-sided 45-degree bevels (with a small flat-ended nose) which are tacked together to meet in the center of the thickness of the material. The Double-V is always welded on both sides of the joint and overall, it is strong and durable.

Single J

One of the metals is prepared with a complete J shape along its edge whilst the other remains square. It is a little complicated in preparation with cutting machinery sometimes necessary for accuracy but will conclude with a decent joint.

Double J

A joint excellent for particularly thick material of 20mm+. Two half Js are prepared on one of the two joining metals with an obvious square spot at its center for a root run.

Single U

One of the most expensive butt joints to produce due to the amount of space necessary to fill with weld material. The joint is prepared by making two half U-shaped preps on each of the ends of the iron which when tacked together, will form a complete U.

Double U

An outwards U shape is prepared on the tips of both sides of the material to allow for a root run at the center of the now hourglass-looking joint. It is most commonly utilized on material over 20mm in thickness making it a large weld with many layers.

Flare Butt Joint

This joint is one where two curved materials meet with the tip of these representing the joint. A fuse or complete weld are common on this joint and are generally laid with ease, however under stress, this joint can break easily.

Flare Bevel

Unique in its characteristics, the Flare Butt joint is made when a flat piece of metal is needed to be joined to one with a bend or with a rounded surface. It is a joint that is usually subject to a lot of stress and is easily welded incorrectly. Depending on the joint in question, one or both sides are fully welded with full penetration and layered welds being important to add strength.

Flare V

This joint is used to attach two metals with a rounded surface such as two bent sheets or two round bars. Weld preparation generally isn’t required, however, layered welds of high quality with a root run are important for structural integrity.

Corner Joint

The Corner joint is a little more complicated to prepare than the butt joint. The two subject metals are tacked together at a 90-degree angle, corner to corner to create a perfect L shape. These joints are brilliant for working on sheet metals with the stainless fabrication industry being the number one user of the joint. Materials of 0.2mm-20mm+ in thickness can be used to create this joint. When the material is below 1.2 mm in thickness extra cautions are advised to minimize unwanted weld penetration and when the material is over 8mm in thickness layered welds are recommended. The major con of corner joints is that they can be temperamental and sometimes difficult to prepare and are subjected to a lot of stress allowing little room for welding error.

Fillet Weld Inside Corner

No preparation is needed for this fillet joint, only tacking the materials together to create the 90-degree L shape. The weld is placed on the inside of the joint and while the joint is of low to medium strength.

Bevel Groove Inside Corner

One of the two metals is prepared with a 45-degree bevel angle which is tacked facing inwards, corner to corner with the other metal piece. It is good for light to medium-sized material and in projects where opening stress is to be present on the L shape of the joint.

Bevel Groove Outside Corner

A joint prepared exactly the same as the Bevel Groove Inside Corner with the exception of the bevel facing outwards. This joint is great for when there is to be closing stress applied to the L joint on light to medium materials.

V Groover Outside Corner

An easy-to-prepare and grunty corner joint where the two metals are beveled with flat tips and tacked facing outward. A root and multiple weld runs are then laid making it a particularly nice joint to use on heavier materials of up to 20mm.

U Groove Outside Corner

A half U is grooved out of each piece of iron using a grinder or special cutting machine then tacked to form a full U shape in the outer corner. With this joint, full penetration is achieved with the root run followed by multiple layers making it a Hulk-like joint with compatibility for 20mm+ material.

J Groove Inside/Outside Corner

The builder prepares the end of 1 piece of metal to form a J groove shape which is tacked to its parent metal. The J will face either inwards or outwards depending on the job. Full penetration is achieved with this joint making it very ideal for heavy materials under regular load.

Single Flare Bevel Groove Inside Corner

No weld preparation is needed as a flared or bent steel piece is tacked to a flat piece with the corner facing inwards. Multiple welds run with a small root are to be placed on this joint with deep penetration in mind while working on materials exceeding 15mm, however, it is possible to use it on any metal over 2mm thick.

Single Flare Bevel Groove Outside Corner

Here a flared or bent steel piece is tacked with its corner facing outwards from the L joint. A beveled piece is then tacked below it to create a Wi-Fi symbol-shaped joint. The S.F.B.G.O.C joint is the ultimate heavy-duty corner joint being able to maintain its integrity under much stress and being utilized from 2mm – 20mm+.

Flare V Groove

Two flared or bent metals are tacked together flush to form a T shape with the joint itself at the top center of the T. Preparation is not always needed but if the joint is going to be under future stress, a slight V groove can be placed at the top center for deeper penetration and an increased backbone.

Edge Joint

An Edge Joint is made when two parallel plates/sheets are fastened together flat, flush, and tip to tip. This joint is generally simple to prepare, easy to weld, and thus, a great joint option for practicing the very basics of welding hand control. This variation of the listed welding joints is only suitable where little to no stress is applied to the weld itself or in other words, the joint is ranked lowest out of all the joints in its strength. Despite this, within the sheet metal industry welders utilize this joint frequently on jobs requiring less durable welds. When the structural integrity of the joint is unimportant to the job, fuse welding can be applied, making it a very economical joint.

Square Groove

The material is tacked together as required and is ready to weld. Square Groove Joints require zero preparation, the penetration and overall durability of the joint are low but despite this, beautiful welds are fairly easy to lay.

Bevel Groove

One of the two materials is prepped with an even 45-degree bevel and square tip across the entirety of its edge. This bevel allows for effective penetration and can be useful for welding materials of different thicknesses. It is important to note that when welding to be careful not to melt away the flat tip of the beveled material if aesthetics is in mind.

V Groove

The strongest of the Edge Joints and great for 2mm+ materials. Two 45-degree bevels are prepared then tacked together to be welded, a root run then multiple welds are laid concluding with a slightly rounded top weld to finish the joint.

J Groove

A J-shaped groove is prepared along the ridgeline of the iron while the other piece remains square. J Grooves are especially handy when you would like to use the Bevel Groove, but with more effective weld penetration.

U Groove

Also, a hearty joint which only differs slightly from the V Groove above. Bevels are prepared on both materials in a J-like shape are then tacked together which then we are left with a ready to weld U-shaped joint. The U Groove provides excellent penetration and strength when welded correctly yet will be deficient if welded carelessly.

Edge Flange Weld

An edge joint where a curved edge meets a square edge. It is most common for the Edge Flange Weld joint to be used on pipe or tube work when attaching a flange to its respectable pipe or tube. If this is the case, skillful preparation is required in the form of a 45-degree bevel placed around the inner circumference of the flange, which is then tacked to the pipe or tube to create the joint. This joint, when used on pipe or tube work, generally requires a skilled tradesperson to prepare and weld it as many processes are important to understand. When this joint is utilized on other materials, the process is simpler and preparation may not be required.

Lap Joint

This joint is exactly what it sounds like, two parallel pieces of metal are tacked together overlapping one over another and that’s it, the Lap Joint is complete! They can be welded solely on one side of the joint or on both although this depends on the job’s reinforcement requirements and also on whether it is functionally possible. This joint is most often found useful when working on lighter materials such as aluminum and stainless steel but can also be utilized on specific heavyweight materials. If preparation is looked over on materials such as carbon steel, rust can occur under the overlap creating major problems in the future.

Single Fillet

Only one of the two overlapping joints is welded. This joint is only recommended for when the strength is unimportant on the job at hand. Single fillets are the most economical of the Lap Joints and require little preparation being commonly used on sheet metal parts in basic production line work.

Double Fillet

Both sides of the joint are welded in the Double fillet. This joint is literally twice the strength of the Single Fillet making it a much more trustworthy option when it comes to long-lasting durability and can be useful for materials with thicknesses of up to 20mm where a decent weld is laid.

Tee Joint

The creation of the Tee Joint is obtained when two metals physically intercept anywhere on the surface of one another making a right angle or T shape. They are never intercepting at the edge of one of the metals as that would make it a Corner joint.

Tee Joints can be welded on one or two sides depending on the requirements of the job at hand. When both sides are welded the joint is exceptionally strong being able to withstand large amounts of stress or pressure making it ideal for heavy fabrication work.  Weld penetration is important with Tee Joints and it is very easy to lay counterproductive welds when careless with welding procedures. With light materials, such as stainless steel, it is easy to over-penetrate the steel which will result in creating “cauliflowers”. These can be extremely problematic when working on food-grade products so having an understanding of the properties of the material itself when working on Tee Joints is of importance.

Square Groove

 The basic version of the Tee Joint where no preparation is needed. This is with the exception of when both sides of the joint need to be welded and, in this case, tacking the other side of the joint may be necessary to prevent the trunk of the T from moving when heat is applied.

J Groove

A J-shaped bevel is created on the edge of the metal which is to be tacked under the head of the T. The J Grooves preparation makes the joint a durable option as you must weld a root run and the multiple welds on top of this.

Bevel Groove

A singular 45-degree bevel is made on the metal to be below the head of the T. This Joint is ideal for welding materials, where making the connection between the two is sometimes difficult such as thicknesses and metal type differences.

Double Bevel Groove

 The Double Bevel Groove is excellent for particularly heavy materials where strength is of the utmost importance. To make this joint, two 45-degree bevels with a flat tip are created on the edge of one of the metals (then it is tacked below the head of the T). Bevel grooves can be used on all materials ranging in thicknesses of 2mm – 20mm+.

Flare Bevel Groove

A curved edge meets a square edge with the Flare Bevel Groove. Depending on job requirements and the layout of the joint, 1-3 welds can be laid on this joint giving it longevity as a joint but perhaps not aesthetically pleasing at times.