Production technology and application characteristics of spiral steel pipe
Spiral steel pipe is a steel coil plate as raw material, often warm extrusion molding, automatic double-wire double-sided submerged arc welding process into the spiral seam pipe. (1) raw material namely strip coil, welding wire, flux.
Before the input must undergo rigorous physical and chemical tests.
(2) Steel head and tail docking, the use of single wire or double wire submerged arc welding, after the coil into the steel pipe with automatic submerged arc welding repair.
(3) before forming, the strip has been leveling, trimming, trimming, surface cleaning and conveying and bending edge treatment.
(4) Use the electric contact pressure gauge to control the pressure of the oil cylinder on both sides of the conveyor to ensure the smooth conveying of the strip.
(5) Using external control or internal control roll molding.
(6) The welding seam clearance control device is used to ensure that the weld clearance meets the requirements, the pipe diameter, the wrong edge quantity and the weld seam clearance are strictly controlled.
(7) internal and external welding are used in the United States Lincoln Welding machine for single or double wire submerged arc welding, so as to obtain a stable welding specifications. (8) The welded welds are inspected by the on-line continuous ultrasonic automatic injury instrument, which guarantees the NDT coverage of 100% of the spiral welds.
If there are defects, automatic alarm and spraying mark, the production workers adjust the process parameters at any time, eliminate defects in time.
(9) Use the air plasma cutting machine to cut the steel pipe into single root.
(10) cut into a single pipe, each batch of steel pipe must carry out a strict first inspection system, inspection of the mechanical properties of the weld, chemical composition, fusion status, the quality of steel pipe and through nondestructive testing, to ensure that the pipe process qualified to be formally put into production.
(11) The Weld has a continuous sonic flaw mark on the site, after manual ultrasound and X-ray review, if there is a defect, after repair, again through non-destructive testing, until the identification of the defect has been eliminated.
(12) The tube of the steel butt weld and the ding-type joint which intersect with the spiral weld are inspected by X-ray television or film. (13) Each steel tube after hydrostatic test, pressure using radial seal. The test pressure and time are strictly controlled by the steel tube hydraulic pressure microcomputer detecting device.
Test parameters automatically print records.
(14) Pipe end machining, so that the end of the vertical, slope and blunt edge of the angle is accurately controlled.
Spiral steel pipe production and use of product characteristics Overview: Hand tool derusting can reach the SA2 level, power tool derusting can reach the Sa3 level, if the steel exterior adhesion strong iron oxide skin, tool derusting effect is not fantasy, not to the anti-corrosion construction requirements of the anchor depth of acid pickling. Straight seam tube under the main stress is perpendicular to the tube impact can be the lowest direction, while the spiral steel pipe staggered the impact of the pipe can be the lowest direction, so that the advantages of the long spiral steel pipe weld to change to the upper hand.
The Anti-Corrosion method of spiral steel pipe also from one of the process of inhibition.
In the process of application, the main stress direction of the helical steel pipe, that is, the length of the pipe axis is less than that of the straight seam pipe, secondly, because the pipeline steel is rolled steel plate, the impact toughness has the greater isotropic, the CVN value of the rolling direction can be 3 times times higher than the CVN value perpendicular to the rolling direction
The use of steel wire brushes and other tools on the surface of steel to stop grinding, to remove loose or warped oxidation of the skin, rust, solder slag and so on.
Hand tool derusting can reach the SA2 level, power tool derusting can reach the Sa3 level, if the steel exterior adhesion strong iron oxide skin, tool derusting effect is not fantasy, not to the anti-corrosion construction requirements of the anchor depth of acid pickling.
Straight seam tube under the main stress is perpendicular to the tube impact can be the lowest direction, while the spiral steel pipe staggered the impact of the pipe can be the lowest direction, so that the advantages of the long spiral steel pipe weld to change to the upper hand.
The Anti-Corrosion method of spiral steel pipe also from restrain one of the process to begin.
If the outer wall of the pipeline with anti-corrosion coating, can increase the circuit resistance, add corrosion current, plus DC power supply, so that the steel pipe on the soil constitutes a negative potential, the formation of cathodic protection, can eliminate yin and yang polar potential difference, from the basic suspension of the process of yin and yang pole.