Straight seam steel pipe refers to a welded steel pipe with one weld in the longitudinal direction of the pipe body. GB/9711.1 stipulates that when the diameter is greater than 914.4, the straight seam steel pipe can have two straight welds, and the angle between the welds is 180 degrees. The welding seam requires the same technical parameters as the straight seam steel pipe as the same welding seam. According to the production process, it is divided into ERW high-frequency straight seam steel pipe, JCOE straight seam steel pipe, and rolled straight seam steel pipe.
Straight seam steel pipe is a general term for high-frequency straight seam, submerged arc straight seam, electric welding straight seam, pipeline straight seam, and other production process products. The high-frequency straight seam steel pipe adopts the skin effect of high-frequency current to generate high temperature at both ends of the steel plate in a short period and is extruded and fused by an external force, which is a real base metal butt joint without a welding rod. ERW high-frequency straight seam steel pipe adopts hot-rolled coil as raw material, and the uniform wall thickness can be controlled at about ±0.2mm. goods and other advantages. In recent years, various gas pipeline network projects and gas companies have widely used ERW steel pipes as the main steel pipes of urban pipeline networks. At present, ERW high-frequency straight seam steel pipe accounts for 60% of the world's steel pipe usage ratio.
The straight seam steel pipe often refers to the double-sided submerged arc straight seam steel pipe produced by JCOE. It adopts the JCOE cold forming process, uses welding wire for the weld seam, and submerges the arc with particle flux at the same time, so it is called the submerged arc straight seam steel pipe. Submerged arc welded straight seam steel pipe is mainly due to its flexible production process, which can produce any specification and wall thickness between 325 mm-1420 mm. It satisfies the steel pipe size standards used by countries all over the world, and high-frequency straight seam steel pipes are usually produced in commonly used specifications.
The high-frequency straight seam steel pipe is usually called the original pipe, and the industry distinguishes it from the submerged arc welded straight seam steel pipe, or the name of the thermal expansion high-frequency straight seam steel pipe is confusing.
To organize the usage guide of welded steel pipe:
It is divided into the following categories: general welded pipe, galvanized welded pipe, oxygen-blown welded pipe, wire casing, metric welded pipe, idler pipe, deep well pump pipe, automobile pipe, transformer pipe, electric welded thin-walled pipe, electric welded special-shaped pipe and Spiral welded pipe.
General welded pipe: General welded pipe is used to convey low-pressure fluid. Made of Q195A, Q215A, Q235A steel. It can also be manufactured from other mild steels that are easy to weld. Steel pipes are subject to water pressure, bending, flattening, and other tests, and there are requirements for the surface. Usually, the delivery length is 4-10m, and it is often required to be delivered in fixed length (or double length). The specification of the welded pipe is represented by the nominal diameter (mm or inch). The nominal diameter is different from the actual one. The welded pipe has two types of ordinary steel pipe and thickened steel pipe according to the specified wall thickness. The steel pipe is divided into two types: threaded and unthreaded according to the pipe end form.
Galvanized steel pipe: To improve the performance of the steel pipe, the general steel pipe (black pipe) is galvanized. There are two types of galvanized steel pipes: hot-dip galvanizing and electric steel zinc. The hot-dip galvanizing layer is thicker and the cost of electric galvanizing is low.
Oxygen-blowing welded pipe: used for steelmaking and oxygen-blowing pipe, generally small-diameter welded steel pipes, with eight types of specifications ranging from 3/8 inch to 2 inches. Made of 08, 10, 15, 20, or Q195-Q235 steel strip. To prevent corrosion, some are aluminized.
Wire casing: It is also an ordinary carbon steel electric welded steel pipe, which is used in concrete and various structural power distribution projects. The commonly used nominal diameter is from 13-76mm. The wall of the wire casing is relatively thin, and it is mostly used after coating or galvanizing, and a cold bending test is required.
Metric welded pipe: The specifications are in the form of seamless pipes, welded steel pipes expressed in millimeters of outer diameter and wall thickness, welded with ordinary carbon steel, carbon steel or ordinary low-alloy steel with hot or cold bands, or welded with hot bands and then welded. Made by cold call method. Metric welded pipes are divided into ordinary energy and thin-walled pipes, which are generally used as structural parts, such as transmission shafts, or conveying fluids, and thin-walled pipes are used to produce furniture, lamps, etc., to ensure the strength and bending test of steel pipes.
Roller tube: used for belt conveyor roller electric welded steel pipe, generally made of Q215, Q235A, B steel, and 20 steel, with a diameter of 63.5-219.0mm. There are requirements for the bending degree of the pipe, the end surface should be perpendicular to the center line, and the ellipticity, and the hydraulic pressure and flattening tests are generally carried out.
Transformer tubes: used to manufacture transformer cooling tubes and other heat exchangers, made of ordinary carbon steel, requiring flattening, flaring, bending, and hydraulic tests. Steel pipes are delivered in fixed lengths or multiple lengths, and there are requirements for the bending degree of steel pipes.
Special-shaped pipes: square pipes, rectangular pipes, hat-shaped pipes, hollow plastic steel doors, and windows steel pipes welded by ordinary carbon-bonded structural steel and 16Mn steel strips, mainly used as agricultural machinery components, steel windows, doors, etc.
Welded thin-walled tube: mainly used to make furniture, toys, lamps, etc. At present, thin-walled tubes made of stainless steel strips are widely used in furniture, decoration, fences, etc.
Spiral welded pipe: It is made by rolling the low-carbon carbon structural steel or low-alloy structural steel strip into a tube blank according to the angle of the helix (called the forming angle) and then welding the pipe seam. It can be made with a narrower strip Steel produces large-diameter steel pipes. Spiral welded pipes are mainly used for oil and gas transmission pipelines, and their specifications are expressed by outer diameter and wall thickness. Spiral welded pipes are single-sided welded and double-sided welded. The welded pipes should ensure that the hydraulic test, the tensile strength of the weld, and the cold bending performance must meet the regulations.