Spiral pipe defect,Technology

Spiral pipe is a very widely used pipe, sometimes it may require welding, but spiral pipe exsit welding defects.

Under normal circumstances, weld defects of spiral pipe has porosity, undercut and crack phenomena.
1, helical tube bubble defects: conducting spiral welded, in the center of the weld bead, there will be the situation of bubble defects, will produce this situation? Main reason is that, in the welding process is hydrogen bubbles form of residue inside the metal. How to solve this failure? Welding process, we need to clear weld the inside of the oil, water and other ingredients, but also need good drying and removing moisture, so that hydrogen does not remain inside the weld . Increasing the welding current in the welding process and the generation of the bubble can be avoided yet.

2, Spiral undercut: v-shaped groove weld edge, and along the weld centerline, said undercut. Usually undercut is inappropriate because of the current, voltage and welding speed, therefore, the need to control the welding process good speed, so as to effectively avoid the biting edge phenomenon.

3, the crack of the spiral welded pipe: spiral cracks may be because of the direction of the spiral weld problems, in order to effectively avoid the spiral cracks in the welding process, the need for strict accordance with the welding process to operate the job.

Spiral pipe for the specific requirements of the strip is advancing the weldability of the steel pipe, to reduce the sulfur content in the steel to improve the toughness of the steel pipe and arrestability are useful. It also reduce the sulfide inclusions to the swap, forward the crack resistance of the steel. The phosphorus content in the hot rolled strip is as low as possible, because, thus lowering the phosphorus content of phosphorus on the toughness and weldability of the steel strip are harmful weldability can advance directly, may be appropriate to add increased titanium, vanadium , the niobium content.

Spiral pipe is containing Ni corrosion resistance in an acidic environment, in the environment containing sulfuric acid or hydrochloric acid, the solenoid the Ni content in the higher the corrosion resistance of the stronger. Under the environment in general, simply adding Cr in the spiral can be prevented the phenomenon of erosion.