Welding is a crucial joining procedure used to weld a wide variety of metals, shapes, and weldments. Pipe welding is one such procedure, which is essential in various industries such as petroleum, oil and gas, plumbing, nuclear, and more.
Welding pipes requires a unique set of skills that include understanding the materials and application, proper fit-up and alignment, and multi-pass operation. Since pipes transfer oil, gas, or toxic chemicals, welds must be of the highest quality and pass critical tests.
In this article, we’ll thoroughly explain the pipe welding technique, including the processes, passes, and pipe welding positions.
What Is Pipe Welding?
Pipe welding is a metal joining procedure that welders use to connect pipes in the construction industry, oil and gas fields, water industries, fabrication shops, and nuclear power stations, among others. Welders use one of many traditional welding methods, such as MIG welding, Stick welding, or TIG welding, to connect the pipes that carry water, oil, gas, petroleum, or various chemicals and transport them across great distances.
The connections between the pipes require critical welds that must adhere to strict welding standards and codes. Some examples are ASME B31.4, B31.8, ASME BPVC codes, AWS D10.12, and AWS D10.18 standards. These codes and standards dictate the weld properties, and the maximum allowed defects, if any, are permitted. Some welders refer to pipe welding as girth welding, as you weld around the circumference of two pipes.
Pipe Welding or Pipeline Welding?
Pipe welding and pipeline welding are two similar terms in pipe joining. While in its core, welders use both to join pipes, there are some differences.
Pipe welding is a procedure welders use to join metal pipes inside plants or oil refineries. Welding these massive pipe structures inside the plants makes the working conditions more manageable.
Pipeline welding is a pipe joining procedure welders use to weld outdoor piping networks. These pipe country networks transport gas, water, oil, and other liquids over many miles. However, this means welders often work in harsh outdoor conditions, especially on the oil and gas piping in the north.
Types Of Piping
Pipes can transfer various chemicals or liquids, but there are several types of piping systems.
- Low-pressure (light structural) piping: These systems transfer non-critical chemicals that are not corrosive, combustible, or hazardous. The weld requirements are the lowest, but the welds still must ensure structural integrity.
- Medium-pressure piping: This piping transfers the low-pressure steam heat, corrosive or flammable chemicals, waste disposal, ship plumbing, and medium-service to heavy-service structural items. Some of the typical applications include welding highway signs, railings or light posts, trailer axles, and equipment frames or stands.
- High-pressure piping: These are the piping systems used in critical applications to transfer high-pressure steam, radioactive materials, or refinery reactor lines. We often see high-pressure piping in the Alaskan pipeline, and the welds must be of the highest quality to withstand harsh conditions and transfer high-pressure liquids across the states.