SPIRAL WELDED STEEL PIPES

Our plant has CQC authorization for manufacturing DSAW Helical Seam Steel Line pipe in diameters ranging from 8.5/8" to 60", in thickness from 5mm to 18mm and Steel Grade up to and including GB/T9711. It has the capability to manufacture pipes up to 90". The production capacity of Pipe Plant is 90,000 tons per annum.

SPIRAL WELDED STEEL PIPE PROCESS

Coils are loaded on the decoiler of the Spiral Pipe machine. The strip is straightened and edges are milled to desired joint geometry. The strip is guided into a forming station, where it is formed to produce a cylindrical hollow body at a predetermined forming angle, ensuring proper welding gap between the abutting edges. Inside, and later, outside welding is performed by an automatic submerged arc process. Pipes are cut to a predetermined length by an automatic plasma arc cutting device. After accomplishment of inside and outside welding, while on the production machine full length of pipe is examined by automatic ultrasonic unit with the help of 8 probes, 4 for checking plate defects and 4 for checking welding defects. Flux and slag from inside the pipes is cleaned. Pipes are inspected for any visual defects. Fluoroscopic inspection of pipes presents the entire spiral seam on visual display for analysis of all the ultrasonic indications for defects, if any, in the weld seam. At the end facing machine both ends of pipes are machined to suit the joint to be used on the pipe line. Each end is worked separately. Each pipe is hydrostatically tested to a given pressure as per API 5L specification or other desired standard. At the end X-ray station radiographs are taken at weld seam for each pipe end to a distance of 4". Every length of pipe is subjected to a rigorous check at the final stand - before it is accepted by the quality control department.