Spiral steel pipe production process

Spiral steel pipe is a welded steel tube made of strip steel coil as raw material, extruded at regular temperature, and welded by automatic double-wire double-sided submerged arc welding process. Because its price is lower than that of seamless pipes, it is more and more widely used in various fields. The main production process is as follows:

(1) Raw materials are strip steel coils, welding wires, and fluxes. Before putting into use, they must go through strict physical and chemical tests.

(2) The head-to-tail butt joint of strip steel adopts single-wire or double-wire submerged arc welding, and automatic submerged arc welding is used for repair welding after being rolled into steel pipes.

(3) Before forming, the strip steel is leveled, trimmed, planed, surface cleaned and transported, and pre-bent.

(4) The electric pressure gauge is used to control the pressure of the cylinders on both sides of the conveyor to ensure the smooth conveying of the strip.

(5) Adopt external control or internal control roll forming.

(6) The weld gap control device is used to ensure that the weld gap meets the welding requirements, and the pipe diameter, misalignment amount and weld gap are strictly controlled.

(7) Both internal and external welding adopt American Lincoln electric welding machine for single-wire or double-wire submerged arc welding, so as to obtain stable welding specifications.

(8) All welded seams are inspected by an online continuous ultrasonic automatic flaw detector, ensuring 100% coverage of non-destructive testing of spiral welds. If there is a defect, it will automatically alarm and spray the mark, and the production workers can adjust the process parameters at any time according to this to eliminate the defect in time.

(9) Cut the steel pipe into single pieces with an air plasma cutting machine.

(10) After cutting into single steel pipes, the first three steel pipes of each batch must undergo a strict first inspection system to check the mechanical properties, chemical composition, fusion status of the welds, surface quality of steel pipes and non-destructive testing. After ensuring that the pipe-making process is qualified, it can be formally put into production.

(11) The parts marked by continuous acoustic wave testing on the welds shall undergo manual ultrasonic and X-ray re-examination. If there are indeed defects, after repairing, they shall undergo non-destructive inspection again until the defects are confirmed to be eliminated.

(12) The pipes where the strip steel butt welds and the D-shaped joints intersected with the spiral welds are all inspected by X-ray TV or film.

(13) Each steel pipe has passed the hydrostatic pressure test, and the pressure is radially sealed. The test pressure and time are strictly controlled by the steel pipe water pressure microcomputer detection device. The test parameters are automatically printed and recorded.

(14) The pipe end is machined to accurately control the verticality of the end face, the bevel angle and the blunt edge.

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