Explained: What is pipe welding?
Pipe welding is a type of welding method that is used to join together two pieces of pipe. Pipe welding can be done with different types of welders, but the most common types are Stick welding (SMAW), TIG Welding and MIG Welding.
Pipe welding and pipeline welding are same term while pipe welding means in broader way for all pipe welding, pipeline welding means the welding of pipe in oil & gas industries.
Pipe welding is used in a variety of industries, including refineries, oil & gas plants, power plant, construction, plumbing, and automotive manufacturing.
Pipe Welding Standards
There are various standards that need to be met in order for the pipe welding to be successful.
The main Pipe Welding standards used in industries around the world are:
- ASME B31.3
- API 1104
- NORS M-601
- ISO 13847
- ASME B31.1
- AWS D10.11
- AWS D10.12
- AWS D10.18
- AWS D10 Series
- CSA Z662
Types of Pipe Welding
Pipe welding is a type of welding that involves joining two pieces of pipes together. There are several different types of pipe welding used in industries as:
- Stick Welding (SMAW): Complete manual welding operation
- TIG Welding (GTAW): Manual
- Orbital TIG Welding: Automatic operation
- MIG-MAG Welding (GMAW): Semi-automatic
- MIG-MAG Welding: Fully automatic systems for orbital welding
- FCAW Welding
Pipe welding types also can be classified based on the pipe manufacturing. This type of pipe welding are listed below:
- Electric Resistance Pipe Welding (ERW)
- Laser Welding (LW)
- High Frequency Welding (HFW)
- Submerged arc welding (SAW)- Spiral (SSAW) and Longitudinal (LSAW) types
What is Stove Pipe Welding?
Stovepipe welding is the term used when a number of pipes are laid and welded together in 5G position one after another to form a continuous line, and welding is carried out vertically downwards, and not by the conventional vertical upwards method which is time consuming and expensive.
Stove Pipe Welding Technique
In this technique, welding starts at the 12 o’clock position on the pipe, and progresses vertically down until the 6 o’clock position is reached. On completion of one-half of the pipe, the opposite side is welded in the same manner, thus producing an endless root run known in the field as a stringer bead.
The second run, known as the hot pass, is then put into the joint. Its name comes from the fact that a high current is used to deposit the run, so as to burn out any defects that may be present from the stringer bead.
With the exception of the final run, all subsequent runs after the hot pass are termed filler beads. Their purpose is to bring the weld deposit to just below the level of the pipe surface. The number of filler beads required will depend largely on the pipe-wall thickness and the preparation.
There are times, however, when it is unnecessary to deposit a filler bead all round the pipe periphery, especially as the weld nears completion. In most cases only the areas between 2 to 4 and 10 to 8 o’clock on the joint will require additional weld-metal.
These concave areas are rectified by the quick deposition of a weld run called a stripper bead, which brings the concave area flush with the remaining weld-metal elsewhere in the joint. To finish the pipe weld the final run is made, which is appropriately called the capping bead.
Stove Pipe Technique Electrode for Pipe Welding
Welding is done with AWS E6010 and E7010, E8010-P1 class electrodes. These electrodes are chosen because the small volume of stiff, thin slag coating deposited on the weld bead, together with the forceful arc, facilitates rapid changes of electrode angle during vertical-down welding on fixed pipes.
To compensate for the thin slag coverage, extra protection from the atmosphere is provided by a gaseous shield of carbon monoxide and hydrogen evolved from the cellulosic coating during welding.
For stovepipe welding, the maximum current specified by the producer for the size of electrode is increased by approximately 10%. DC supply with electrode positive polarity (DCEP) is used for pipe welding.
Process and Steps of Pipe Welding
The main steps for Pipe Welding are:
- Pipe marking
- Weld joint preparation
- Pipe joint alignment for welding
- Tack Welding
- Root Run Welding
- Fill pass and Capping weld
- Final weld Inspection
Pipe Welding Tools
Pipe welding tools are mandatory as these tools help to make right alignment of pipe before welding, handle large pipes, prepare weld bevel, etc.
The main pipe welding tools are:
- Welder- TIG, MIG or Stick (SMAW)
- Pipe stands
- Alignment clamps- Chain clamp, cage clamp, internal alignment clamp
- Pipe welding clamp
- Pipe Jacks
- Pipe Carts
- Pipe marking tools
- Pipe centering head
- Wrap around pipe wrap
- Centerline punch
Pipe Welding Positions
Most of pipe welding jobs are carried out in 5G Welding positions as pipes are mostly laid horizontal in oil & gas industries. In power plant or other constructions, pipe welding is carried out in:
Related reading: Learn Pipe Welding Positions using Welding Positions Chart
How to be a Pipeline Welder?
Pipe welding is a specialized trade that involves joining together sections of pipe to create a pipeline. Welders in this field must be able to work in a variety of conditions, often in cramped spaces and uncomfortable positions.
Pipeline welder must also be able to read and interpret welding blueprints and have a strong understanding of the welding process, welding techniques and safety aspects.
To become a pipeline welder, it is recommended that you start by completing an welding apprenticeship program. Many welders learn their trade through on-the-job training, but an welding apprenticeship will give you the chance to learn from experienced welders and receive formal instruction in welding techniques and safety procedures from welding trainer.
Related Reading: How much do welders make a year? The answer might surprise U
Once you have completed an apprenticeship or have gained enough experience on the job, you can apply for welder certification through the American Welding Society (AWS) sense program or a welding school.