What is a spiral steel pipe?

Spiral steel pipe is manufactured from steel coil, extruded at room temperature, and then welded using double wire and double-faced submerged-arc techniques.

Spiral steel pipe, also known as spiral or helix spiral steel pipe, is a low-carbon steel or low-alloy structural steel strip rolled into a tube with welded joints at a certain helix angle (called molding angle). It is possible to make it using a thin strip of large-diameter tubing.

Steel plate has consistent deformation and little residual stress during the molding process of spiral-welded steel pipe, resulting in no scratches on the surface. Spiral steel pipe offers more flexible thicknesses and diameters, particularly when constructing high-grade thick pipes with tiny or medium apertures; these techniques have unmatched benefits in meeting your requirements.

Reasons for spiral steel pipe's magnetic field

Welding by DC welding, in the welding line, and the position of the welding head due to the high current, resulting in a strong magnetic field, the pipe body under the action of the magnetic field, the magnetic moment, or the tendency to obtain an external magnetic field in the same direction, are arranged in the welding process. When the welding process is completed, the magnetic field steadily decreases until it disappears owing to the hysteresis phenomena in the tube body and residual magnetic flux density, which is what we call remanence.

The dangers of magnetic fields in spiral steel tubes

Existing remanent magnetization, the image intensifier, the electron beam deflection, and the X-ray industrial TV image system all resulted in "s" type distortion, influence porosity, slag, and other natural defects, particularly the detection rate of incomplete penetration, cracks, and other linear natural defects.

The persistence was especially noticeable with the adjustment and improvement of the X-ray image intensifier TV system pipeline steel grade.

The existence of remanence, or ring butt, in the pipeline will result in the phenomenon of partial arc, or welding quality.

The effects of permanence have had a significant impact on building quality.

The most popular spiral pipe degaussing method is AC degaussing.

Wrap the coil around the exterior of the steel tube, connect the coil to the alternating current, and gradually lower the alternating current until it is zero. Degaussing results in no change in the physical qualities of spiral steel pipe, but when exposed to an external magnetic field again, spiral steel tube becomes magnetized.

Through the heat treatment process, the degaussing can be done more thoroughly; however, after degaussing, the hardness and rigidity of the spiral pipe will change, and the spiral pipe will be exposed to the external magnetic field again in the future.

The heat treatment technique is most likely: oxygen-free heating to a specified temperature,and then slowly cooling to room temperature for 72 hours.