ERW, SSAW, LSAW welded steel tube

    ERW steel pipe: high-frequency straight seam resistance welded pipe, using hot-rolled wide coil as the material, through pre-bending, continuous forming, welding, heat treatment, sizing, straightening, blocking and other processes, it has a shorter weld seam than the spiral, standard High precision, uniform wall thickness, good surface quality, and high-end benefits under pressure, but the defect is that only small and medium-diameter thin-walled pipes can be produced, and the welds are prone to gray spots, unfused, and groove-shaped corrosion defects. At present, the widely used fields are city gas, crude oil products and oil transportation, etc.

    SSAW steel pipe: spiral submerged arc welded pipe, which has a forming angle (adjustable) with the center line of the forming pipe when the pipe is rolled, and is welded while forming, and its welding seam is formed into a spiral line, and the same standard can produce a variety of diameters Standard steel pipe, the material is used to planning larger, the weld can avoid the main stress, the stress is better, the defect is a few standards are poor, the length of the weld is longer than that of the straight pipe, the crack is easy to crack, the slag is included, the welding deviation, etc. Welding defects, welding stress is tensile stress. The general design rules and regulations of long-distance spiral submerged arc for oil and gas pipelines can only be used in category 3 and category 4 areas.

    LSAW steel pipe: Straight seam submerged arc welded pipe, which is made of a single medium-thick plate by pressing (rolling) the steel plate in a mold or forming machine, using double-sided submerged arc welding and expanding the diameter to produce. Its product standard planning is wide, and the resistance, plasticity, uniformity and fineness of the weld are good. It has the advantages of large pipe diameter, pipe wall thickness, high pressure resistance, low temperature resistance and corrosion resistance. When creating high-strength, high-endurance, high-quality long-distance oil and gas pipelines, most of the steel pipes required are large-diameter thick-walled straight-seam submerged arcs. According to API standard rules, in large oil and gas transportation pipelines, when passing through Class 1 and Class 2 areas such as the seabed in high cold areas and densely populated urban areas, the straight-seam submerged arc is the only designated pipe type.