The first part of the fire-resistant spiral steel pipe
copolymer adhesive part of the functional group and the epoxy primer epoxy group can react to form hydrogen bonds or chemical bonds, so that the middle layer and the bottom layer form a good bond; non-polar ethylene part It has good affinity with the surface layer polyethylene, so the middle layer and the top layer also have good bonding properties. The main function of the polyethylene surface layer is to provide mechanical protection and corrosion protection, and has the same effect as the traditional two-layer polyethylene anti-corrosion layer.
The following describes the production process of fire-resistant spiral steel pipe:
(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 is used after the steel pipe is rolled.
(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 inner and outer welding are performed by single-wire or double-wire submerged arc welding using a Lincoln electric welder in the United States to obtain stable welding quality.
(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 steel pipe is cut into individual pieces by an air plasma cutting machine.
(10) After cutting into a single steel pipe, each batch of steel pipe shall undergo a strict first inspection system to check the mechanical properties, chemical composition, fusion condition, surface quality of the steel pipe and non-destructive testing to ensure the pipe making process. After that, 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 joint intersecting the spiral weld are all inspected by X-ray television or film.
(13) Each steel pipe is subjected to 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. 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. Weld processing spiral steel pipe feeds the strip steel into the welded pipe unit. After rolling through multiple rolls, the strip is gradually rolled up to form a circular tube blank with open gap. The reduction of the pressing roll is adjusted to control the weld gap. At 1~3mm, the ends of the solder joint are flush.