Square Tube (SHS) Production Process:
(1) Raw materials are strip coils, welding wire, flux. Strict physical and chemical testing is required before input.
(2) The steel head and tail are butt jointed, and the single wire or double wire submerged arc welding is used, and the automatic submerged arc welding repair welding is adopted after being rolled into a square pipe.
(3) Before forming, the strip is leveled, trimmed, planed, surface cleaned and pre-bent.
(4) The electric contact pressure gauge is used to control the pressure of the cylinder on both sides of the conveyor to ensure the smooth conveying of the strip.
(5) Adopt external control or internal control roll molding.
(6) The weld gap control device is used to ensure that the weld gap meets the welding requirements, and the pipe diameter, the amount of misalignment and the weld gap are strictly controlled.
(7) Both internal and external welding are performed by single-wire or double-wire submerged arc welding using a Lincoln welding machine in the United States to obtain stable welding specifications.
(8) The welded seams are all inspected by online continuous ultrasonic automatic injury inspection to ensure the non-destructive testing coverage of 100% spiral welds. If there is a defect, the alarm is automatically alarmed and sprayed, and the production worker adjusts the process parameters at any time to eliminate defects in time.
(9) The square tube was cut into individual pieces by using an air plasma cutting machine.
(10) After cutting into a single square tube, each batch of three tubes must be subjected to a strict first inspection system to check the mechanical properties, chemical composition, fusion condition, surface quality of the square tube and non-destructive testing. After the pipe making process is qualified, it can be officially put into production.
(11) The part of the weld with continuous acoustic flaw detection mark, after manual ultrasonic and X-ray review. If it is defective, after repair, it will pass the non-destructive test again until it is confirmed that the defect has been eliminated.
(12) The tube of the butt weld of the strip and the joint of the butt intersecting the spiral weld are all inspected by X-ray television or film.
(13) Each square tube is subjected to hydrostatic pressure test and the pressure is radially sealed. The test pressure and time are strictly controlled by the square tube water pressure microcomputer detection device. Test parameters are automatically printed and recorded.
(14) The pipe end is machined to make the end face verticality, groove angle and blunt edge accurately controlled.
