Welded steel pipes are often used in various engineering projects. 

How is a welded steel pipe made?

Most welded steel pipes are from steel plates and steel strips. These strips and plates are made by moving steel loops and coils with a proper thickness gauge to form a leveled material. The flat-leveled material is then measured and cut to the desired lengths.

The process starts with bending the steel plate, and then it is welded to the desired shapes, be it a circle, rectangle, square, and many more using a progression of bending machines or rollers. The metallic pipe weld uses a powerful energy source. Some pipes can also be welded together with filler material. Most welded steel pipes must pass through the heat treatment process.

The weakest piece of a welded steel pipe is always the joints. The weld joint’s quality determines the quality of a welded pipe—welding with a robot mostly in automated production lines such as in the automobile industry. Alternatively, for stronger steel pipe welds, human labor has proven to be perfect; for example, in aerospace construction.

The welded pipe starts out as a long, winding ribbon of steel called a skelp. The skelp is cut to the desired length, resulting in a flat rectangular sheet. The width of that sheet’s shorter ends will become the pipe’s outside circumference, a value that can be used to calculate its eventual outside diameter.

The rectangular sheets are fed through a rolling machine that curls the longer sides toward one another, forming a cylinder. In the ERW process, high-frequency electrical current is passed between the edges, causing them to melt and fuse together.

An advantage of ERW pipe is that no fusion metals are used and the weld seam cannot be seen or felt. That’s opposed to double submerged arc welding (DSAW), which leaves behind an obvious weld bead that must then be eliminated depending on the application.

Welded pipe manufacturing techniques have improved over the years. Perhaps the most important advancement has been the switch to high-frequency electric currents for welding. Prior to the 1970s, the low-frequency current was used. Weld seams produced from low-frequency ERW were more prone to corrosion and seam failure.

Most welded pipe types require heat treatment after manufacture.

Cangzhou Shenlong Pipe Manufacturing Co., Ltd. cooperates with Baosteel and Baogang to produce large-caliber seamless steel pipe, straight-seam welded pipe, spiral steel pipe, and pipe fittings. The products comply with API, ASTM, DIN, BS, and JIS standards, and can accept SGS, BV, and other inspections. The products are used in oil, natural gas, bridge, water conservancy, and other large-scale projects, which are worthy of trust.