In accordance with the cross-section and shape, spiral pipe is divided into the sub-shaped tubes and tube. Perimeter commensurate area of a circle is the largest, so you can transport more liquid. Therefore, the vast majority is circle tube, each spiral are tightly controlled after the hydrostatic test, the test pressure and the time by the steel pipe pressure microcomputer monitoring device, the test parameters automatically printed record.
The specific requirements of spiral strip is to forward the weldability of steel pipe, to reduce the sulfur content in the steel is beneficial to improve the toughness of the steel pipe and crack arrest. This can also reduce the sulfide inclusions, transfers, advance steel crack resistance. Phosphorus content in hot-rolled strip is as low as possible, because the phosphorus on the strip, toughness and weldability harm, thus reducing the phosphorus content can be directly forward weldability may be appropriate to add additional titanium, vanadium, niobium content.
Spiral tube containing Ni in an acidic environment, the corrosion resistance is strong, containing sulfuric acid or hydrochloric acid environment, the higher the spiral of Ni content, the stronger the corrosion resistance. In general circumstances, only in the spiral Cr can prevent the erosion phenomenon.