▶ Spiral welded pipe unit:

Spiral welded pipe unit is a steel pipe formed by rolling a low carbon structural steel or low alloy structural steel strip into a pipe billet by a forming machine according to a certain molding angle, and then welding the spiral pipe seam together with a submerged arc welding machine. The advantage is that the narrower strip steel can be used to produce large diameter steel pipe.

Spiral welded pipe unit can spiral coil the strip steel cylindrical pipe body, welded by automatic welding equipment, according to the strip width, thickness and diameter of the pipe to calculate the molding angle used to adjust the position of the molding rollers.

▶ Usage:

Spiral welded steel pipe is mainly used for the transportation of oil and gas transmission and natural gas, and can be used for the transmission of water, steam and other pressurized pipelines, used in petrochemical, heat pipelines, building structures and other projects.

Spiral welded pipe unit is divided into two ways: front-swing intermittent production and back-swing continuous production. The back-swinging continuous spiral welded pipe production line is mainly used for the production of pipes for the transportation of oil and natural gas.

▶ Spiral welded pipe unit process flow:

Stacking of raw materials - Unwinding - Flattening - Cutting of strip head and tail - Butt welding --Milling - Forming - Inside welding - Outside welding - Cutting - X-ray imaging -Cutting - X-ray inspection - Tube end weld trimming - Tube end expansion -Hydrotesting - Ultrasonic flaw detection - Flattening - Tube end taping - Weighing and length measurement - Taping -Weighing and length measurement - Marking - Oil coating - Packaging and storage

▶ Spiral welded pipe equipment using the production process:

(1) Raw materials i.e. strip coil, welding wire, flux. Before putting into the strict physical and chemical inspection.

(2) Strip steel head and tail docking, using single-wire or double-wire submerged arc welding, in the coil into a steel pipe after the use of active submerged arc welding filler.

(3) Before molding, the strip steel through the leveling, shearing, edge planing, exterior cleaning delivery and pre-bending edge treatment.

(4) Adopt electric contact pressure gauge to control the pressure of press down cylinder on both sides of the conveyor to ensure the smooth transportation of strip steel.

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

(6) Adopting weld gap control device 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) The internal and external welding are all single-wire or double-wire submerged arc welding by American Lincoln electric welding machine, so as to obtain stable welding quality.

(8) The finished weld is inspected by on-line ultrasonic active injury detector, which guarantees the coverage of non-destructive testing of spiral weld. If there are shortcomings, active alarm and spray marking, production workers adjust the process parameters accordingly.

(9) Use air plasma cutting machine to cut the steel pipe into single.

(10) cut into a single steel pipe, each batch of steel pipe should be carried out strict inspection system, check the mechanical properties of the weld, chemical composition, solubility, surface quality of the steel pipe as well as through the nondestructive testing inspection, to ensure that the pipe manufacturing process is qualified before officially put into production.

(11) The weld has continuous acoustic flaw detection marking parts, after manual ultrasonic and X-ray review, if defects, after repair, again after the nondestructive testing, until confirming that the defects have been cleared.

(12) The pipe where the strip butt-welded seam and spiral welded seam intersect and d-type joints are located is examined by X-ray TV or film.

(13) Each steel pipe undergoes a hydrostatic pressure test, and the pressure is radially sealed. Test pressure and time are strictly controlled by the steel pipe hydrostatic microcomputer monitoring device. The test parameters are automatically printed and recorded.

(14) Pipe ends are mechanically processed so that end face verticality, bevel angle and blunt edges are accurately controlled.