The use and production process of spiral pipe

Spiral pipe, also known as spiral steel pipe or spiral welded pipe, is a low carbon structural steel or low alloy structural steel steel strip according to a certain angle of the helix (called molding angle) rolled into a billet, and then welded the pipe joints made of it, it can be used to produce large diameter steel pipe with a narrower strip.

Uses: Spiral pipe is mainly used for oil and natural gas transportation pipeline, its specifications are expressed by OD * wall thickness. Spiral pipe has a single-sided welding and double-sided welding, welded pipe should ensure that the hydraulic test, the tensile strength of the weld and the cold bending performance in accordance with the provisions.

Production process:

(1) raw materials, namely, strip coil, welding wire, flux. All of them should undergo strict physical and chemical inspection before being put into use.  

(2) The strip steel head and tail are butt-jointed, and single-wire or double-wire submerged arc welding is used, and automatic submerged arc welding is used to make up the welding after it is rolled into a steel pipe. 

(3) Before forming, the strip steel is leveled, sheared and shaved, and the surface is cleaned and conveyed and pre-bent edges are processed.  

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

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

(6)Weld gap control device is adopted 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 carried out by American Lincoln electric welding machine for single wire or double wire submerged arc welding, so as to obtain stable welding specification.  

(8)The finished welds are inspected by on-line continuous ultrasonic auto-injurer, which ensures 100% NDT coverage of the spiral welds. If there are defects, automatic alarm and spray marking, production workers accordingly adjust the process parameters at any time to eliminate defects in a timely manner.  

(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 carry out a strict first inspection system, check the mechanical properties of the weld, chemical composition, dissolution conditions, the surface quality of the steel pipe as well as non-destructive testing to ensure that the pipe making process is qualified before officially put into production.  

(11) The weld has continuous acoustic flaw detection marking of the parts, after manual ultrasonic and X-ray review, if there are defects, after repair, and again after nondestructive testing, until the defects are confirmed to have been eliminated.  

(12) Strip butt-welded welds and the pipe in which the d-joints intersecting with spiral welds are located, all of which are examined by X-ray television or film.  

(13) Each steel pipe is subjected to a hydrostatic test with radial sealing pressure. The test pressure and time are strictly controlled by the steel pipe hydrostatic microcomputer testing 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.