Pipe Welding : The Definitive Guide [2020]

Pipes are essential and so is pipe welding, if often invisible, part of the modern home, factory, vehicle, and storage unit, doing their part to keep devices functioning and moving needed substances from one place to another.

Some pipes are small, such as the water pipes and heating pipes in an individual house.

Others are gigantic, such as the oil pipelines that snake across the landscape of Alaska, Venezuela, Iraq, and Kazakhstan, and then there are those which carry processed food, oil, gas, grain, and a thousand other substances from one part of a factory to another.

Pipes, like all other metal objects, have joints where one piece meets another, and these joins are usually sealed and strengthened by welding. 

Significance of Pipe Welding

Small pipes in the house may simply be soldered, but any more ‘serious’ pipe is certain to be welded wherever one section meets another.

Welding pipes is a unique challenge because of their round cross-section.

A continuous weld must be made around their entire circumference with enough precision to make all points of the weld equally strong under pressure (or the contents will inevitably seek out the path of least resistance and possibly burst the weld at the weak point).

Since the pipes are usually welded in the place where they are installed, without being rotated, meaning that a means must be found of welding all sides of the pipe – even when some sides are inaccessible to a human welder because they are a few inches from a wall or high up near the ceiling.

To circumvent this problem, pipe welding machines or as otherwise known as pipe fabrication machines operate on the “orbital welding” principle.

In orbital welding, a circular track is attached around the pipe, with the welding gun or torch mounted on this track. 

The hoses connect the ring and welding gun to the main body of the machine, as well as a control panel or even a computer used to program the welding job. 

Once programmed and activated, the welding gun “orbits” in a steady loop around the pipe, welding all sides in a complete circle as it goes, and forming a thorough, complete, solid weld with far more precision than even the most skillful human hands could ever hope to achieve.

Pipe welders are subjected to a lot of harsh conditions, they sometimes even weld in the rain to get the project done in time.

You might have seen tents used by them who work in remote locations, on the other hand some use welding umbrella to maintain efficiency under the sun.

Pipe Welding Machine

Pipe welding machines are large, able to handle pipes that may be larger in diameter than the height of a human being, and certainly able to weld pipes of a few feet in diameter. 

These pipe welding machines are meant for the many large-scale pipe welds that are needed in the modern world. 

Offshore oil platforms, oil tankers, water pipes supplying drinking water to millions of people in a city, pipes at food processing plants, sewage systems, and many other pipes are all-welded employing orbital welders – although oil pipelines are an exception to this rule.

An orbital welding machine of this size usually has an intricate control computer to allow great precision in welding. 

Pipe welding jobs are huge and time-consuming, but they also have very exacting requirements because pipes of this size generally see massive daily use and are subjected to constant weight and pressure. 

For this very reason, the orbital welder must be programmed by a skillful, experienced operator who will be able to set the welder up to obtain the best possible weld.

Portable Pipe Welding Machines

Thanks to the miniaturizing technology of the modern era, portable pipe welding machines no larger than ordinary ones are also readily available. 

These pipe welders use an orbital welding arrangement as well so that they can weld pipes that are fixed in place and cannot be rotated for welding. 

These small, lightweight machines put orbital pipe welding not only within the reach of employees of major corporations and government agencies, but individual welders, independent plumbers, and other people interested in welding pipes. 

Such portables such as the PipeMaster can handle pipes as small as 1” in diameter, as well as those several inches larger.

Pipe welding is one of the most difficult welding tasks that may confront the worker in steel and aluminum, but human ingenuity has devised the tools necessary to handle pipe welding tasks large and small with efficiency, effectiveness, and a good deal of precision.

Why is Pipe Welding Crucial?

Snaking across the landscape for hundreds of miles like the arteries of the internal combustion engine society, oil pipelines are among the most dramatic welded objects visible in the everyday world. 

The subject of controversy and debate, the root of many economic and technological processes, these immense pipes need to be welded together to extremely high standards.

Millions of gallons of extremely heavy oil will flow through each pipeline in a given month, putting the welds that hold the innumerable sections together under great stress. 

With these characteristics, and with the rugged outdoor working conditions under which pipelines must be assembled far from the level, well-lighted confines of a factory floor, making pipeline welding very valuable but difficult at the same time.

Surprisingly, much of pipeline welding – unlike other welding involving large pipes – is carried out by hand rather than with orbital welding machines. 

Each weld is made by a team of highly skilled welders, and requires five passes, using a shielded metal arc machine with DC reverse polarity.

The joint is prepared by being preheated to around 400 degrees Fahrenheit with propane torches. 

The shielded metal arc process, otherwise known as MMA( Manual Metal Arc) welding or stick welding, involves using consumable electrode rods with a heavy flux coating that vaporizes during welding to produce a cloud of shielding gas around the weld point. 

Stick welding is especially good for outdoor operations and is used for this very same reason, as well as its ease and cost savings.

When the weld is complete, it is inspected both visually and with x-rays to ensure that it has been made properly and will not rupture when the oil is pumped through the pipeline. 

The welders, in the meantime, have moved on to the next joint in the pipe, keeping up their assembly-line welding procedure.

Special Design Features of Pipeline Welding Machines

There are several features which makes a pipe welding machine different from others.

So What Makes A Pipe-Welding Machine Stand out?

Since a pipeline welding machine is inevitably used in the field, rather than in a factory or workshop, it has several differences from the machines manufactured for use in these controlled environments.

The first design feature that is likely to be noticed by an observer is that pipeline welding machines are equipped with a diesel engine.

Typically a four-cylinder, water-cooled engine, this is necessary because there is simply nowhere to plug in the machine, so it must generate its power. Sometimes as a replacement engine-driven welders are used which efficiently does the work.

Placing the generator inside the machine rather than in a separate device means that there are fewer pieces of equipment to handle, no problems with connecting the generator to the machine, and less maintenance to be carried out. 

Fuel tanks of up to fifteen gallons are included to ensure that frequent refueling will not be necessary.   

Other features include a pure DC power generation, which can supply 200 amperes or more for 7/32” low-hydrogen electrodes. The machines are built with versatility in mind and can switch over to MIG and TIG welding, as well as carrying out arc gouging.

Most are set up to shut down automatically when oil pressure becomes low or the water temperature of the water cooling system becomes dangerously high. 

These features allow the welder to work with confidence, knowing that they will not burn out their system on the demanding work that is involved in pipeline construction. 

Pipeline welding machines are tough, flexible, and self-contained – qualities that are necessary to handle these intensive welding jobs which are carried out in less than ideal conditions.

Pipe Welding Positions

Like every welding method, Pipe-Welding also has some positions on which the quality of the weld depends. The top four positions used in pipe-welding are one, two, five, and six.

• 1G Pipe Welding Position

The not-so regularly used basic 1G position is utilized in pipe welding by beginning the arc from the center of your tack. The gun and pipe should be perpendicular to each other. Also, 5/8 of your stick should be out.

• 2G Pipe Welding Position

The 2G position is fixed, it requires you to be stationary and layout the pipe vertically. Thus it can be rotated along the Y-Axis. However, You cannot weld and rotate the pipe at the same time.

• 5G Pipe Welding Position

Similarly to the 2G position, the pipe is fixed and the welder begins at the center of a tack weld, then moves around the pipe to perform the welding. 

• 6G Pipe Welding Position

The pipe is fixed at a 45-degree angle in the 6G Pipe Welding Position. This position requires expertise and practice as the welder must go around the pipe and weld it at different angles. 

Pipe Welding Tests

Being the most crucial type of welding, it does require some rigorous testing.

The welded pipes are examined and checked for any weak areas or any other faults.

Several different types of tests are used for testing a pipe-weld. Sometimes tests can be destructive and hence can destroy the welds. Therefore NDT( Non-destructive testing) is done which ensures the welds are still intact 

• X-Ray Test

The Pipe Weld is checked for any faults via an X-Ray and ensures the internal quality is well. While it is the best for spotting- faults but on the other hand is very expensive. It works similarly to the X-Ray tests done on a human body.

• Macro Etch Test

This involves cutting a small sample of welded joints and dipping in an acid solution. This test checks for the macro structural integrity of the weld and shows any signs of crack, porosity, pinholes, and other defects.

• Bend Test

To determine the strength, the weld is bent to a defined shape usually its 180 degrees. This test thoroughly checks the face(façade) and the root(Foundation) of the weld by applying pressure on those areas.

• Fillet Break Test

The root penetration of the weld is checked via a Fillet break test, which is usually at the start and end of the weld. To pass the test the weld will bend flat, without fracturing. An exception of 10mm for the cracks is exempted.

If you don’t want to conduct any test that is expensive or if you are low on budget, you can simply visually inspect the weld for any faults. Inspectors can spot any discontinuity pretty easily. Also try the electromagnetic test, by inducing electric and magnetic currents. Any defects can be spotted pretty easily via these two tests. 

Pipe Welding Jobs

So, you have all the theoretical and practical knowledge regarding pipe-welding and love it. What next? There are several different options available to you. 

You can either get a pipe-welding certification from one of the leading welding schools or start up your own small welding business and get yourself a pipe-welding truck, As professional welding doesn’t require any degrees.

Mastering 1,2,5,6 and R position is all you need to know to pass a hands-on welder qualification test. 

After getting your certifications, you can look for jobs near you or join a welders union such as pipeliners which eases up the process of getting a well-paid job with other compensations.

There are ample of opportunities abroad which gives huge pay with many other benefits.

If you land a job, Don’t forget to get those pancake welding helmets which pipe welders usually wear. Yeah, they are awesome.

Conclusion

Now you know everything related to pipe-welding, now it’s your turn to apply the gained knowledge.

The top welders are the ones who grab the very first opportunity and weld the perfect joint.

You’ll gain other required knowledge as you practice more, that’s the only way to grow in the field of welding. You can’t expect yourself to be perfect after reading instead of applying the knowledge.

Don’t forget your safety equipment.

Happy Welding!