Longitudinal Pipe Mill

High Grade and High Quality Longitudinal Seam SAW Pipes (Straight Seam Pipes)

Pipes are formed starting from the plate set in the edge milling machine and rolled in the three-roll bending machine designed by Haeusler from Switzerland. The rolled cylinder is then processed into the edge crimping machine prior to tack welding. Tandems inside SAW and outside SAW are then performed to ensure a joint efficiency factor of 1. Mechanical expanding is conducted next for 0.8%-1.5% expansion ratio to relieve the pipe of its accumulated stresses during forming and welding processes. Mechanical expanding enhances the dimensional parameters. Hydrostatic testing, ultrasonic inspection, X-ray inspection, and final, visual and dimensional inspections are also conducted. The mill proven capability for producing high strength heavy wall line pipe is up to X70.

NPC offers a wide choice of pipe diameters from 24”-60” (610-1524 mm) and 0.250” -1.200” (6.4 - 30.5 mm) wall thickness with grades ranging from API 5L Grade B - X70 and pipe length of up to 40 feet (12 meters).

LPM Process Flow Diagram