Pipe Welding Technique: Everything You Need to Know
While pipe welding is a better way of connecting pipes than threading them, it is often more challenging than welding flat metal surfaces. However, it is a skill you must master as you advance in your welding career, as at some point, you will probably encounter a job where you have to do some pipe fabrication. That said, you should always start by understanding what this welding is all about.
Pipe Welding Basics
When you are starting on pipe welding, you cannot afford to overlook the basics. Hence, before you start learning or doing pipe welding, you must establish a good welding technique.
Like any other welding, pipe welding often involves different techniques like TIG welding, Arc welding, and MIG welding. Therefore, it is vital to make sure you have a good understanding of these welding techniques.
Another fundamental thing to keep in mind is that you have to learn all the safety techniques and have the necessary safety gear, from auto-darkening helmets and safety goggles to welding boots and flame-resistant clothing.
Like any other type, pipe welding requires you to prepare the materials before you start by sanitizing them and doing other things like grinding or beveling thick edges.
Pipe Welding Positions
You can utilize four different welding positions in pipe welding, and they are number between 1 and 6.
- 1G Rolled Position: While it is not used as frequently as the other 3, the 1G rolled position is the most basic. Since the pipe is typically lying on its side, welding in this position is more similar to welding a flat surface, and it is hence the easiest.
- 2G Position: For the 2G position, the pipe you want to weld will be vertical, and you have to do the job from a horizontal position. Since the tube is on its base, it is more stable to weld, but you cannot turn it when welding.
- 5G Position: Like 1G, the 5G position has the pipe placed horizontally on the surface, but unlike the former, it cannot move as it is in a fixed position. Hence, when welding, you have to do it from various positions that sometimes include overhead, making it more challenging.
- 6G Position: The 6G position often requires a lot of training and practice as it is the hardest to implement. Here the pipe is placed at a 45-degree angle, and it does not role, meaning the welder has to weld from four different positions, which can be pretty hectic.
Testing Your Pipe Welding
It is vital to examine your pipe weld's strength or weakness, and here the following NDT (non-destructive testing) methods are the best as the weld remains intact after the test.
- Visual Inspection: The cheapest and easiest way to inspect a pipe weld is through a visual check. Here you only need to look at the weld's quality and use your experience to determine whether it is strong enough. But since it is more subjective, it is not always a very reliable test.
- X-Ray Test: If the pipe welding job you are doing requires the best quality welds to ensure safety, an x-ray test is the most reliable way to check your welds. Here, you have to do an x-ray of the weld and check for cracks and imperfections. Despite being the most effective test, it is the more expensive and comes with greater risk for the welder.
- Dye Penetration Test: Here, you have to brush or spray the dye on the metal's surface to highlight cracks and imperfections that you cannot see with the naked eye.
- Fillet Break Test: For this test, you examine root penetration and not the depth of penetration. If your weld passes this test, it means it can lie flat on itself without fracturing or splitting.
- Bend Test: The bend test uses a jig to bend the weld to a defined shape. Its primary purpose is to check the weld's rigidity, and it determines its quality at the face and root as these are the areas where you impose tension.
Common Issues in Pipe Welding
Mistakes on piper welding are common for both beginner and experienced welders, but a clear understanding of the common ones makes them easier to avoid.
Spatters occur when molten metal scatters to unwanted areas when welding, and it often results in an unsightly weld and can also cause injuries to the welder or starts a fire.
What to Do: The best way to deal with a spatter is to ensure you have the correct welding gas combination. Using a short arc, applying correct polarity, and moving at a proper angle can also help.
2. Parts Misalignment
Parts have to fit perfectly in pipe welding to ensure the weld holds well and looks good. Sometimes welders will rush a weld and end up with misaligned parts.
What to Do: The best way to ensure you do not have misaligned parts is never to rush through a job. However, tack welds can be very helpful here.
Porosity will occur when welding gases like hydrogen, nitrogen, and oxygen are absorbed into the weld pool. A temporary disruption in the flow of gas also often leads to porosity.
What to Do: Always make sure you clean and grind the metal surface before you start welding. Ensuring there is no blockage in your gas pipes, hoses, or torch can help as it provides a smooth gas flow.
4. Slug Inclusion
Slug inclusion is where you end up with nonmetallic particles on your weld, and it often occurs when you have improper access to the joint or use poor welding techniques. However, flux coating can also contribute to this issue.
What to Do: The best way to avoid slug inclusion is to maintain proper speed and correct angle, as this minimizes slug levels. Additionally, using the appropriate voltage can help prevent this problem.
Pipe welding requires a lot of practice and a good understanding of the techniques involved. Making good preparation before you start the job is also very crucial. Once you do all that and make sure you do not repeat the common pipe welding mistakes many welders make, you should be okay.