Large diameter spiral steel pipe is a general name, generally refers to a spiral steel pipe with a diameter greater than 1 meter. Spiral steel pipes are made by bending and then welded.
The steel pipe must be subjected to hydraulic pressure, bending, flattening and other tests. There is a certain requirement for the surface quality, usually the delivery length is 12 meters, often requires a fixed-length delivery. When the large-diameter spiral steel pipe is produced, the wrong side occurs from time to time. There are many influencing factors. In the production practice, the steel pipe is often degraded from the wrong side. Therefore, it is necessary to analyze the causes and prevention measures of the misalignment of large-diameter spiral steel pipe. Here's a brief description of the production process of large-diameter spiral steel pipe: the raw material is strip coil, welding wire, flux. Have to go through rigorous physical and chemical tests before investing. The butt joints of the steel strips are welded with monofilament or double wire submerged arc welding. After the steel tubes are rolled into a steel tube, they are welded with automatic submerged arc welding. Before forming, the strip is leveled, trimmed, edged, surface cleaned and pre-flanged. Electric contact pressure gauge is used to control the pressure of the compression cylinders on both sides of the conveyor to ensure the smooth delivery of the strip. External control or internal control roll forming is adopted. 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 all strictly controlled. Both internal and external welds were made using the United States Lincoln Electric Welder for monofilament or double wire submerged arc welding to achieve stable weld quality. The welded welds were all inspected by an online continuous ultrasonic flaw detector to ensure a non-destructive test coverage of the spiral weld. If there are defects, they will be automatically alarmed and painted. The production workers will adjust the process parameters at any time to eliminate defects in time. An air plasma cutter cuts the steel tube into individual pieces. After cutting into a single steel pipe, each batch of steel pipe must undergo a strict first inspection system to check the mechanical properties of the weld, the chemical composition, the fusion condition, the surface quality of the steel pipe, and the nondestructive inspection to ensure that the pipe manufacturing process is qualified. Formally put into production. Welds with continuous acoustic flaw detection marks are subjected to manual ultrasonic and X-ray reexamination. If there is a defect, after repair, it is subjected to nondestructive testing again until it is confirmed that the defect has been eliminated. The butt-welded joints of the steel butt-welded joints and the spiral welds were all examined by X-ray television or film. Each pipe was hydrostatically tested and the pressure was radial sealed. The test pressure and time are strictly controlled by the steel pipe hydraulic pressure testing device. Test parameters are automatically printed and recorded. Pipe end machining, so that the end face perpendicularity, groove angle and blunt edge are accurately controlled.