Welding is a very serious kind of job. During any construction process, a significant portion of the success rides on good quality welding. Especially in the case of welding pipes, you have to know the basics and have a good grasp of all the techniques required for a good weld.
Choosing an effective method of welding pipes together depends on a few factors like the welding finishes, the sophistication of the work, and the economy. The most common methods are – stick welding, TIG welding, and MIG welding. There are also laser welding, atom Hydrogen welding, and electron beam welding which are done by expert welders.
In this article, I’m going to talk about 7 most effective ways to weld pipes together. Along with some techniques, I’ll also provide some tips for achieving the best results. So, without further ado, let’s get right to it.
Fundamentals Of Pipe Welding
Welding is a fabrication process that utilizes extreme temperature and pressure for melting and fusing two metal parts. Here are a few essential pointers about pipe welding to get you started on the right foot.
Before starting any welding job, make sure you have enough preparation and equipment for finishing it. Ensure that all safety gears and protective equipment are running and functioning correctly without any problems.
Good preparation and sanitization of your material will ensure lesser hassle for you during the work. The protective gears you need to prepare are an apron, safety helmets, rough clothing, goggles, work boots, and earmuffs.
The most rudimentary piece of advice for suitable welding is to hold all the materials together. The best way to achieve this is to tack weld them all together.
After finishing the tack welding, you’ll have enough time in your hand to weld everything together in an accurate manner and with careful observation. You can also cut out and feather your tacks to drastically reduce the number of imperfections on your welding.
Gravity is also an essential factor while you weld because it constantly attracts the pipe to fall to the ground. So, keep in mind that no matter how easy or technical it gets to weld each side, the bottom part will always remain much more challenging to handle than the top.
Divide the pipe you’re working on within different segments. The place to begin working is from the top, then gradually stopping towards the 45º angle.
You want to ensure your comfort and safety before starting the next steps. Don’t forget to intertwin the tacks properly in the middle of each run. Repeat this process till you complete rotating the entire weld.
Pipe welding is different from the other types of welding as it often uses heavy-duty and thick materials. Moreover, pipe welding has a unique characteristic known as the open root, which means a welder needs to ensure complete penetration of the pipe for completing the welding process.
It can be challenging to weld both the internal and the external sides of the pipe for a welder. So, it is crucial to get good quality welding done on the pipe.
A pipe with poor welding can bring disaster to the whole construction if it ever gets broken or leeches liquids. If you’re looking to solve this problem, groove welding is advisable.
There are different welding methods for pipe welding, suited for different situations and finishes. Some standard methods are the stick method (SMAW), MIG method, and TIG method. We’re mentioning their functionality along with their use case scenarios below:
1. Stick/Arc Welding (SMAW)
SMAW stands for Shielded Metal Arc Welding technique, also known as the stick or arc welding technique. Generally speaking, this is the default and most widely used process for welding any type of pipe.
This method uses a consumable electrode with a flux-coated core wire used for providing electrical current. Despite extensive use, it is not arguably the best method for welding pipes.
The electrode creates a metal arc after coming in contact with the metal, and this method can generate high temperatures up to 3500°C. However, it is beneficial for use because this method does not require any type of shielding gas and is very effective on rusty metals.
It is also a little harder to master than other welding methods like MIG welding, but most of the equipment needed for this method comes very cheaply.
2. Tungsten Inert Gas Welding (GTAW)
The Tungsten Inert Gas Welding, or TIG Welding for short, is a welding method that became popular during the 1940s. However, welding metal with this process is quite complicated, time-consuming, and needs a high skill level.
You can weld two pieces of metal together without the need for any filler material; it’s also an autogenous method for welding. As a result, it produces a very high quality of welding without any spatter, and you can construct multiple thin alloys in this method.
For pipe welding, this produces a beautiful-looking weld without any cracks or imperfections on the joint. However, to get the best out of this particular welding technique, you need to be highly skilled, and you also need an external shielding gas. Moreover, this process is not suitable to use in rusty or dirty metals.
If you’re looking for the cleanest, consistent, and reliable method of welding that will last you for ages, this is the welding method to go with.
3. Metal Inert Gas Welding (GMAW)
Metal Inert Gas, also known as MIG, which involves a consumable electric gun that is fed constantly, is used to weld in this method.
An external gas like Argon or Helium is effective in this process for shielding the metal from different environmental factors, like oxygen. This, in turn, makes the whole welding process very quick and continuous.
This is quite an easy method to go for if you’re new to the welding world. It produces fewer fumes than its other counterpart techniques and requires much lesser heat input to function correctly. This method also comes with higher electrode efficiency.
MIG welding is the default choice for many DIY enthusiasts and people who don’t have too much money to spend on higher-priced equipment.
4. Flux-Cored Arc Welding (FCAW)
The Flux-cored Arc Welding is a method similar to that of MIG. But the main difference between these two methods is that MIG uses a solid wire for welding, whereas arc welding employs a tubular wire.
This method is very effective against thick materials like heavy pipes. It is also perfect for repair works and construction because it is relatively easy and cost-effective.
You can optimize this method by using a self-protecting shield for yourself. Moreover, you can also dual-shield it with different inert gases like Helium or Argon.
5. Electron Beam Welding (EBW)
Electron Beam Welding, or EBW for short, is a process of fusion welding in which the welders generate a lot of electrons with an electric gun. These electrons are then accelerated to very high speeds by the usage of electrical fields.
After speeding up the electric fields, they are then focused tightly using a distinct magnetic field for the welding operation. As a result, this creates a very high amount of kinetic heat, which melts the metals and bonds together.
You should absolutely perform EBW under vacuum conditions, as gas can easily scatter the magnetic beam. Therefore, this process is computer-controlled and automated for its vacuum requirement and usage of extremely high voltages.
This is a useful method for extremely precise welding requirements and not very practical for daily usage. It is also costly and requires a high level of expertise.
6. Atomic Hydrogen Welding (AHW)
Atomic Hydrogen Welding, or AHW, is a thermo-chemical welding process requiring two tungsten electrodes for producing the arc necessary for the welding. It is also done in a Hydrogen gas chamber.
The arc helps disassociate the Hydrogen molecules into their atomic forms to provide enough heat and energy for welding. A filler might be an optional accessory in this method, which the process may or may not require.
In this method, a very high amount of heat, ranging from 3400 up to 4000°C. Moreover, using the atomic hydrogen gas and the electric arc generates this much heat. It is a welding method for metals that needs extremely high temperatures to work in, like Tungsten.
The main difference between AHW and TIG is that the arc one electrode is responsible for forming the arc in the MIG process. In comparison, two electrodes form the arc in the AHW process.
7. Laser Welding
In laser welding, the protocol is fundamentally different from the typical process used in pipe welding. In this method, a laser beam helps join or weld a thermoplastic or metal.
Laser welding uses high power density lasers with a method known as the keyhole mechanism. A machine then concentrates the laser into a tiny spot for producing power density greater than 100 watts per square centimeter area. In this high-energy state, the laser can melt the metal and bond them together.
The angle of your weld dictates the flow of the filler material. And, this can gravely impact the quality of your weld. So, knowing about all the pipe-welding positions is essential for any welder.
Now, the positions can be categorized into four: number one, two, five, and six (1G, 2G, 5G, and 6G). Here, I’m highlighting all the pipe welding positions below:
Let me begin by explaining to you the most basic welding position known as the 1G rolled position. Along with its primary application, this position is not very popular for regular welding.
The process is quite similar to flat welding; the pipe lays on the side. While you weld the pipe, you can rotate it by the horizontal axis. Fix your weld position in the puddle center while you roll the pipe away from you as you weld it. In this position, the welder’s place will remain stationary while he welds the top of the pipe.
To get the most successful weld in the 1G position, start by placing your arc on the center of your tack. Keep the gun and pipe perpendicular to each other with the drag angle around five to ten degrees. Keep your stick at ⅝ inches or less.
The 2G position keeps the pipe in a vertical position. Therefore, while you weld the pipe, you can rotate along the vertical line or the Y-axis. The welder will remain stationary in this position, although the welding should be performed on the pipe side in the horizontal direction.
This position implies that you cannot rotate the pipe while you weld; you must pre-rotate to a fixed position then continue welding. While you keep yourself in a fixed place, make sure the pipe is on its bottom part. That will make it more stable for the welding more effectively.
In the 5G welding position, the welder keeps the pipe stable horizontally or along the X-axis. Thus, unlike we see on the 1G position, the pipe remains fixed in a particular position.
That, in practice, means that the welder is unable to rotate the pipe while he welds. So, he has to move around the pipe in the Y-axis to perform the welding operation.
The welding process begins within the center of the tack weld keeping the five to ten degrees of drag angle along with the stick out that matches the length. After completing the root pass, you also have to grind out the beginning and end of the welding before you make the fill between.
The novice welders will find the process for 6G welding to be quite laborious and taxing. Because in the position, the pipe needs to be fixed at a 45º angle. What it means in practice is the welding has to be done in all places, including the strong sides and weaker sides of the welder.
The pipe is usually sloped at around 45º angle from the horizontal X-axis or the vertical Y-axis. Welders keep the pipe at a fixed position, which means he needs to rotate around the pipe to perform and complete the entire welding process. This process is not recommended for novice welders as it requires a ton of experience and technical knowledge to perform correctly.
After finishing the welding work, you have to make sure the whole process is done perfectly. Or else, there could be catastrophes along with complete system failures.
So, some of the more used techniques for testing your pipe welding are properly mentioned below.
Visual inspection is the quickest, easiest, and cheapest method for inspecting your pipe welding. A qualified inspector who has a lot of ideas about welding is the best choice for this job. He will provide valuable insights on whether the weld is of poor quality or the whole construction is in danger or not.
This method is entirely subjective and requires the inspector to look at the pipe to determine its quality. Moreover, identifying the discontinuity in welding and visual flaws could lead to weld failure, and the whole piping system is critical in this regard.
Although this method might work very well in some aspects, it is not reliable to detect internal weld defects.
Bend is another type of physical test which determines the structural rigidity and toughness of the welding. The primary purpose of this test is to determine whether the welding is structurally rigid enough or not. The tested specimen is usually bent up to 180 degrees to test its strength and structural rigidity.
The bend test mainly determines the quality of the weld in two main areas. First, the facade or the face of the joint and the root of the joint are checked for testing. Then, after imposing tension in these areas, it is determined whether the joint holds together or not.
Liquid dye penetration testing involves spraying a dye on top of the metal surface of the welding. Then the liquid is kept there and given enough time to seep through any surface imperfections. After a few hours, the extra fluid is removed from the welding surface.
After the surface dries up slowly, you can see the imperfections on your welding. This is because the dye inflicts a chemical reaction that highlights the defects in the welding invisible to the naked eye.
This method is a much better alternative to the visual inspection test, as the inspector can quickly determine any imperfections on the surface. It is also relatively cheaper.
X-ray testing is the most effective and practical method for inspecting the welding of a pipe. This method is exceptionally effective for examining any kinds of external and internal flaws in the welding. Especially in jobs where the quality of the wield is of utmost importance for safety reasons, X-ray testing is a must.
This method works similarly to human x-rays; a cathode ray tube is fitted into the welding area. Then imaging of the whole internal and external areas of the welding is taken.
The X-ray method is very sophisticated and expensive. Therefore, only professionals should perform it.
The Fillet breaker test is essential for examining the root of penetration for the welding. That includes the beginning portion and the ending portion of the weld because of their failure tendencies. The testing involves bending the welds in different directions to test the breakpoint of a weld.
If the weld can bend without falling apart completely, the test is a success. But one thing to keep in mind is that the cracks and fractures should not go beyond 10 millimeters.
In this method, cut a sample from the welding portion and take it for inspection. Then polish the sample, and apply an acid solution to the surface.
The solution lets you inspect various macro-structural integrity of the welding. For example, you can examine cracks, porosity, grain size, mold slag, unsoundness, hydrogen flakes, etc., via macro etch testing.
There are certain things you need to consider for better welding. Following these tips will give you peace of mind and a more rigid and good quality welding to the pipes.
Clean Out Impurities
The first thing you need to ensure before starting the entire welding process is to clean out the outer and inner surfaces of the pipes. This includes removing paints, dirt, rust, and other contaminants that can affect the welding quality.
Cleaning will remove all the imperfections, contaminants, and impurities that can get into the metal during the welding process. If this material stays behind during the welding, it will create defects and potential weak points in the welding.
You can use a wire brush to clear out all the rusts and dust on top and inside the pipe.
MIG Gas Selection
For carrying out MIG welding, the preferred gas mixture uses 100% CO2, as it is an economical option and will provide you with deep welds.
If you have some time and money to invest in getting some nicer quality shielding gases, here are some options for you.
- 75% Argon along with 25% CO2 will give you better-looking welds.
- 85% Argon along with 15% CO2 is best for welding heavier steels.
- 100% Argon is effective for welding aluminum pipes.
- 90% Argon mixed into 7.5% Helium along with 2.5% CO2 is best for welding stainless steel.
Glob Or Spray Modes for Thick Steel
Adjusting the voltage, ampere, and speed of the wire welding can fine-tune the welding on thick metal. This is great for heavy pipes that have more steel.
There are two types of transfer modes available – globular transfer and spray arc transfer. The globular transfer mode is suitable for thinner pipes with less steel in them. While the spray arc mode is better for thicker and heavier pipes as it provides deep penetration and greater power.
Rules On Angle, Direction, And Speed
The rules to get better-looking and better-quality welds depend on a few critical things. With these things in mind, you can expect to get a wider range of success with your welding every time.
- Push or Pull: If you’re using a stick or flux-core welding, drag the rod. Or else, if you’re using a MIG welding, push the rod.
- Angle: The angle where to hold the gun depends on various welding styles. If you’re welding with wires, keep the gun at around a 15° angle. For stick welding, you have to keep the angle at around 30° angle.
- Arc Spacing: For MIG welding or flux-core welding, keep the working distance around ⅜ to ½ inches. Keep the distance at around ⅛ inches if you’re working with a stick welding.
- Speed: If your weld speed is too slow, it will produce convex beads with shallow penetration, and you’ll waste a lot of metal. If your weld speed is too fast, you will produce a narrow bead on the other hand. The recommended speed for welding jobs is around 40 inches every minute.
- High-strength Steel Mending: As most of the pipes have very high-strength steel in their construction, it is crucial to know how to weld them in place properly. Before starting the welding process, preheat the site and clean out all the rusts and dust from the area. Preheating is a crucial step to stop the phenomenon called post-weld cracking.
- Using a small diameter with how-hydrogen content will produce a deeper weld. During the welding, keep the welding speed slow and steady, as it will boil out the hydrogen gas and produce good, consistent welding.
Know When to Reinforce
Reinforcing is a valuable concept when it comes to welding pipes. After the welding, there might be some cracks or faults in some areas. A good practice is to reinforce the points of the pipe with higher stress points, such as joints, junctions, and bends.
It is better to bevel the new material with the old materials at a 30° angle to provide a better welding penetration during the reinforcing procedure. For heavier and bulkier pipers, you should perform reinforcement in multiple passes to get the best result.
Even the most expert welders face issues and can end up making mistakes in their welding jobs. So here are a few of the most common mistakes you should look out for and avoid while welding pipes.
- Incomplete Preparation: When it comes to welding, preparation is a critical step. You need to properly clean your pipes, prepare the joints, and test if the parts fit with each other. Moreover, ensure the edges are smooth enough by grinding them beforehand.
- Misalignment: Misalignment might result in structural failure and too many steep curves in the welding. If welders rush through the whole process without taking necessary steps, this might happen.
- Undercutting: Undercutting is also a common problem in pipe welding. Stuff like low voltage, wrong angle, or not using the proper electrode can cause this.
- Improper Tacking: Tacking is a must for ensuring proper pipe fit-up, and the tacks left in the joint get consumed by the welding process. The defect in tacks or using the wrong filler material can cause welding defects.
- Porosity: The problem often causes porosity in the gas flow, loose connections, improper shielding gas, or even not preparing correctly.
- Cracks: Cracks will cause you to start over the welding from scratch. So the best way to get rid of this problem is to use precise temperature, cleaning the surface properly, and grinding the surface adequately.
- Spatter: Spatter refers to the material scattering which melts near the welding arc. This is caused by using longer arcs, incorrect polarity, giving extra electricity, etc.
- Slag Inclusion: The slag occurs because of the incorrect flux coating. For reducing this problem, you should weld at a proper speed and angle, perform adequate cleaning and correct the voltage usage.
Good quality pipe welding depends on many factors, and I tried to provide you with answers for all of them. I’ve also mentioned the various types of methods that are best for different scenarios. For enthusiasts, I suggest going for the Tungsten Inert Gas or TIG method. If you’re low on budget, you can also go for the stick method.
Now that you’re familiar with the 7 most effective ways to weld pipes together, I hope you’ll use this knowledge to improve your pipe welding skills. Good luck with your next welding job!