Spiral Steel Pipe Manufacturer: Some Basic Facts About Longitudinal Seam Steel Pipes

　　 Spiral steel pipe Manufacturers believe that straight-seam steel pipes are widely used in industries such as petroleum, metallurgy, construction, coal mining, port operations, and machinery. The installation and use of straight-seam steel pipes are subject to stringent technical requirements and should be carried out in accordance with actual conditions to ensure quality. During normal operation, the following points should be observed:

　　1. Installation of straight-seam steel pipes. According to spiral steel pipe manufacturers, pipeline positioning must be carried out strictly in accordance with the design drawings. Pipe supports should be prefabricated on-site based on actual conditions, followed by on‑site cutting as required. Chamfering is then performed using a polishing machine, after which welding is executed. Quality requirements: for horizontal installations, the deviation per meter shall be less than 1 mm; for vertical installations, the deviation per meter shall be less than 3 mm. Branch pipes and elbows must not be welded directly onto the weld joint. Weld seams shall be smooth, uniform, and fully filled, with no burn-through or cracks on the surface.

　　2. Spiral steel pipe manufacturers emphasize that straight-seam steel pipes have stringent technical requirements during equipment installation and must be installed inside the pipeline. Based on actual conditions and operational guidelines, what precautions should be taken when using straight-seam steel pipe equipment to ensure safety and quality? Trenches have been excavated according to the drawings, pipe inspection chambers have been constructed, and all required straight-seam steel pipes have arrived; the materials are of good quality and have passed inspection. Additionally, the necessary construction equipment—such as electric welders, cutting machines, rotary hammers, and polishing machines—has been prepared. With these preparations in place, the initial equipment installation can proceed smoothly.

　　3. Arrange the piping according to the engineering drawings, prefabricate pipe supports based on site conditions, perform on-site cutting and material preparation as scheduled, then use an angle grinder to bevel the edges before proceeding with welding. During the welding process, feed the steel strip into the welded pipe mill; through multiple rolling passes, the strip is gradually formed into a circular tube blank with an open cavity. Adjust the diameter‑reducing nip rollers to maintain a weld gap of approximately 3 mm and ensure that both ends of the weld are flush.

　　Spiral steel pipe manufacturers note that if the open gap in a straight‑seam steel pipe is too large, the proximity effect weakens, eddy currents are insufficient, and the weld may fail to penetrate or crack due to poor intergranular bonding. Conversely, if the open gap is too small, the proximity effect intensifies, leading to excessive heat input and weld damage; after upsetting, the weld may develop deep pits, compromising surface quality. Branch pipes must not be welded onto the weld seam, and welding at bends should be avoided. For vertical equipment risers, the deviation per meter shall be less than 3 mm; for horizontal equipment risers, it shall be less than 1 mm. The surface of straight‑seam welded pipes shall be smooth, with no wrinkles, cracks, delamination, or overlapping defects. Minor surface imperfections on straight‑seam pipes must not exceed the negative tolerance of the wall thickness.

　　Spiral steel pipe manufacturers emphasize that, during the production of straight‑seam steel pipes, it is essential to carefully control the extrusion pressure. This is because, during welding, once the edges of the two pipe blanks reach the welding temperature, a specific amount of pressure must be applied to promote mutual penetration of the metal grains, forming tightly bonded crystals and achieving a strong weld. However, if the extrusion is insufficient, the crystals will not form properly, resulting in low weld strength and increased susceptibility to cracking under external loads. Conversely, excessive extrusion can cause the weld metal at the intended joint to be squeezed out, leaving only a minimal amount of material actually fused together; this reduces the number of crystalline bonds and leads to inadequate weld strength, as well as the formation of significant burrs—defects that are quite serious.