What is welded steel pipe?
Welded steel pipes are manufactured by rolling steel plates or strips into a cylindrical shape and then joining the seams through welding. Their defining characteristic is the presence of one or more welded seams.
Unlike seamless steel pipes, which are formed by piercing solid steel billets, welded steel pipes undergo a "from flat to round" manufacturing process. This involves first transforming flat plate material into a circular shape and then welding the seams together.
Core Manufacturing Process
The production of welded steel pipes primarily involves the following key steps, with slight variations depending on the specific process:
| 1.Raw Material Preparation | Utilizing steel coils (strip steel) or steel plates as raw materials. |
| 2.Forming | Gradually rolling flat plates into circular, square, or other desired shapes using a series of rollers. |
| 3.Welding | This is the most critical step. The seam formed during rolling is welded to create a seamless, integrated structure. Various welding techniques are employed (see below). |
| 4.Weld Finishing | The weld is trimmed (removing internal and external burrs) and undergoes heat treatment (to relieve welding stresses). |
| 5.Sizing and Straightening | Rollers precisely adjust the pipe to the target dimensions and straighten it to ensure straightness. |
| 6.Cutting and Inspection | The pipe is cut to specified lengths and undergoes rigorous quality inspections (such as hydrostatic testing and non-destructive testing). |
Primary Welding Process Types
The performance of welded steel pipes is largely determined by their welding process. Below are several mainstream techniques:
|
Welding Process |
Features |
Primary Applications |
|
Electric Resistance Welding (ERW) |
High-frequency current is used to heat the edges of the pipe blank, which is then formed by extrusion. This process offers high efficiency, low cost, and produces a relatively smooth weld seam. |
Low-pressure fluid conveyance pipes, structural pipes (such as scaffolding), furniture pipes |
|
Submerged Arc Welding (SAW) |
The arc burns beneath the flux layer, producing welds of exceptional quality, making it ideal for thick-walled, large-diameter pipes. It is categorized into longitudinal submerged arc welding (LSAW) and submerged submerged submerged arc welding (SSAW). |
Longitudinal Submerged Arc Welding (LSAW): Oil and gas trunk pipelines, high-pressure equipment Spiral Submerged Arc Welding (SSAW): Piling pipes, drainage pipes, low-pressure fluid conveyance |
|
Laser welding |
High-energy laser beam welding offers exceptional precision with a minimal heat-affected zone, making it ideal for precision thin-walled tubes. |
Automotive exhaust systems, precision mechanical components, home appliances |
|
TIG/MIG Welding |
Using inert gas shielding ensures pure welds and high quality, making it suitable for stainless steel and alloy steel. |
Stainless steel piping for chemical equipment, food, and pharmaceutical applications |
Summary
Welded steel pipes are an economical and highly versatile steel pipe product manufactured through welding processes. Modern welding technology has reached a high level of maturity, and high-quality welded steel pipes (such as LSAW pipes used in the West-East Gas Pipeline) deliver exceptional performance capable of meeting the demands of most industrial applications.
The key selection criteria are:
If you require low-cost, large-diameter piping for structural support or low-pressure fluid conveyance, welded steel pipes are the ideal choice.
We are able to provide high quality Welded Steel Pipe according to customers' needs and look forward to your purchase.
