The high-frequency welding process of straight seam steel pipe is completed in the high-frequency welded pipe unit. The high-frequency welded pipe unit is usually composed of roll forming, high-frequency welding, extrusion, cooling, sizing, flying saw cutting, etc. The front end of the unit is equipped with a material storage looper, and the rear end of the unit is equipped with a steel pipe turning frame; The electrical part is mainly composed of a high-frequency generator, DC excitation generator, and instrument automatic control device. The thermal expansion straight seam steel pipe refers to the expansion of the straight seam steel pipe through the expansion technology to meet the needs of customers. There are two types of double-sided submerged arc welding and high-frequency welding for straight seam steel pipes. Double-sided submerged arc welding can produce straight seam steel pipes with a diameter of about 1500. The expansion pipe we are talking about now mainly refers to high-frequency welded pipes. There are two points The reason is that the production diameter of the high-frequency welded pipe itself is relatively small, so it needs to be expanded.
There are many types of straight seam steel pipes, according to their uses: generally welded pipes, oxygen is blown welded pipes, galvanized welded pipes, wire casings, idler pipes, metric welded pipes, automobile pipes, deep well pump pipes, transformer pipes, electric welding special-shaped pipes, electric welding thin-walled pipes.
General welded pipe: General welded pipe is used to transport low-pressure fluid. Made of Q235 grade, L245, and Q235B steel.
Galvanized steel pipe: It is to coat the surface of the black pipe with a zinc layer. Divided into hot and cold. The hot zinc layer is thick, and the coldness is cheap.
Oxygen-blown welded pipe: generally, small-diameter welded steel pipe is commonly used for oxygen-blowing in steelmaking.
Wire casing: It is a pipe for a power distribution structure, which is an ordinary electric welded carbon steel pipe.
Electric welding thin-walled tube: It is a small diameter tube used for furniture and lamps.
Idler tube: The electric welded steel tube above the belt conveyor has the required ovality.
Transformer tube: It is an ordinary carbon steel tube. Used in the manufacture of transformer heat pipes and other heat exchangers.
Requirements for the appearance of straight seam steel pipe:
1. No cracks, unfused, pores, slag inclusions, and splashes are allowed.
2. The welding seam surface of pipelines with design temperature lower than -29 degrees, stainless steel and alloy steel pipelines with greater hardening tendency shall not have undercut. The undercut depth of the welding seam of other materials shall be greater than 0.5mm, the length of the continuous undercut shall not be greater than 100mm, and the total length of the undercut on both sides of the weld shall not be greater than 10% of the total length of the weld.
3. The surface of the weld shall not be lower than the surface of the pipe. The excess height of the welding seam shall not be greater than 3mm, (the larger width of the rear groove of the welded joint group).
4. The wrong side of the welded joint should be no more than 10% of the wall thickness and no more than 2mm.
Post time: Sep-07-2022