News

Welding Procedures for Steel Pipes

Welded steel pipe refers to a steel pipe with a seam on the surface, which is formed by bending and deforming a steel belt or a steel plate into a circular or square shape. The blanks used for welded steel pipes are steel plates or strips.

According to different welding methods, it can be divided into arc welded pipe, high frequency or low frequency resistance welded pipe, gas welded pipe, furnace welded pipe, Bondi pipe, etc.

Welding procedure:round tube billet → heating → perforation → three-roller cross-rolling, 
continuous rolling or extrusion → tube removal → sizing (or reduced diameter) → cooling → straightening → hydraulic test (or flaw detection) → marking. 

According to the shape of the weld, it can be divided into straight seam welded pipe and spiral welded pipe.

Straight seam welded pipe: simple production process, high production efficiency, low cost and rapid development.

Spiral welded pipe: The strength is generally higher than that of straight seam welded pipe. It is possible to use narrow blanks to produce welded pipes with larger diameters. It is also possible to use the same width of blanks to produce welded pipes with different pipe diameters. But compared with the straight seam pipe of the same length, the length of the weld seam is increased by 30-100%, and the production speed is lower. Therefore, the weld pipes with smaller diameter are mostly welded by straight seam, and the weld pipes with larger diameter are mostly spiral welded.

Spiral welded steel pipes are divided into two types: automatic submerged arc welded steel pipes and high frequency welded steel pipes.

a. Spiral Straight seam welded pipe seam automatic submerged arc welded steel pipe is divided into two types according to the pressure level of the conveying medium. Class A pipes are generally welded with ordinary carbon steel Q235, Q235F and common low-alloy structural steel 16Mn. Class B pipes are welded with Q235, Q235F, Q195 and other steels, and are used as low-pressure fluid delivery pipes.

b. Spiral seam high-frequency welded steel pipe Spiral seam high-frequency welded steel pipe, there is no unified product standard, generally made of ordinary carbon steel Q235, Q235F and other steel materials.

Know more about this product price, catalogue, mill test certificate,  please inquiry to: sales@nan-steel.com

Contact