What is Pipe Welding? – Everything you need to know

Introduction:

Welded Pipes are most commonly used in the Oil and Gas industry to ship oil and gas to refineries and export terminals from the oil fields. You must have seen them in your everyday life around you for supplying water to us and also in sewerage lines. They are also used in large-scale pipeline projects. We might not have realized that we are somehow dependent on these pipes as without them it would be difficult to drive or even drink water and cook food. Let’s discuss the whole process of welding pipes. 

What is Pipe Welding?

Pipe welding means joining two pipes together with a collection of techniques of welding that includes connecting metal pieces together and heating in a way that it results as a one piece of metal. To maintain the standardized practice and obtain flawless results, pipe welders (also known as pipefitters) require special skills and have to learn in-depth about it.

Different welding techniques are used as per the specifications and the final product desired by various industries. Pipe welding mostly requires Arc welding processes. As there are multiple processes the selection is done on the basis of the product requirement and the industry demands. 

What are the types of Arc Welding Processes used?

Pipe Welding can be achieved using some of the following arc welding processes:

1. Gas Metal Arc (GMAW) / MIG / MAG Welding

GMAW attempts to provide high deposition rates with low fume generation and is generally accomplished with semi or fully automatic equipment. GMAW offers higher productivity, proficient work and delivers high quality when given preferred control of the welding variables.

2. Shielded Metal Arc (SMAW)/ MMAW/ Flux Shielded Arc Welding/ Stick Welding

As the name suggests, no flux or shielding gas are required for pipe welding. This makes the welding equipment uncomplicated, compact and handy. An electric Arc generates the heat and melts the electrodes, which is how the metal is welded. But the travel speed is slow, hence it’s not considered as the most productive process, despite having some advantages.

3. Tungsten Inert Gas (TIG) Welding / GTAW

Welders’ skill set becomes the priority factor when using this process for pipe welding. TIG surely creates exceptional quality welds and is considered to be an absolute choice for complex, critical and highly precise welding jobs. Its equipment cost is huge as compared to other pipe welding processes and it has low deposition rates.

4. Flux-Cored Arc Welding(FCAW)/ Self Shielded FCAW/ Gas-shielded FCAW

 Gas Shielded FCAW does provide high productivity welding results using semi-automatic welding equipment. But if the weather conditions or surroundings are windy then it can interfere with the shielding gas which can lead to porosity defects. While in case of Self-shielded FCAW, this kind of situation can be avoided as it does not need a shielding gas, but it has lower deposition rates.

5. Submerged Arc Welding

Out of all the pipe welding techniques, this process provides the highest deposition rates. It is a semi-automatic process and also delivers defect-free surfaces. But because during this process the arc is not visible, one might have difficulty in tracing.

Steps to follow for Pipe Welding: 

Factors affecting Process Selection: 

Pipe – material, wall thickness and diameter, health & safety, Welding – quality required and location along with direction that can be downhill or uphill, Budgetary considerations, Weldment prospects. 

Assessment to determine Equipment: 

Depending upon the factors, you can opt for the equipment required by assessing its – Safety, transportability, flexibility, output power and Duty Cycle.

Usually following are the Steps to be followed once the equipment is selected to begin the welding:

1. Relevant guidelines should be followed which are set out by the applicable standard, while taking the first step of Joint Preparation.

2. Remove all the unwanted moisture or coatings that include varnish, paint, oil or rust by doing Pipe End Cleaning. This will ensure the prevention of re-welding, defects and or expensive repairs.

3. To begin with the Welding – accurate materials (electrodes included) and parameters like preheat requirements, etc. are selected as per the particulars needed. Pipe Welding can start only with these passes:

1. Root Passes: These passes are the first initial pass that fills the gap between the two pieces of the pipes. 

2. Hot Passes: This pass follows to join both the groove faces with the root weld.

3. Fill Passes: This is the second last step to fill out most of the groove.

4. Cap Passes: The role of these final passes is to weld with as little build up as possible beyond the surface of the pipe. If required then you can grind this layer back. It can help in removing contamination and can improve weld beading before the final finishing cap passes.

4. Check the weld and make sure to Repair any defects if required. 

Types of Positions of Pipe Welding

There are 4 types of Welding positions:

Conclusion:

To conclude we have tried to cover everything we need to know about Pipe Welding. You can select the process as required using the information provided above. We would be glad to have feedback from our readers. It helps us to give better output every time, when we get connected to our viewers. Keep viewing, keep learning and stay connected with us.

Title: What is Pipe Welding? – Everything you need to know