According to the API/ASTM stadnards, there are many technical requirements for producing welded steel pipe.

The nominal pipe diammeter ranges from 6-150mm, nominal wall thickness ranges from 2.0-6.0mm and the length of the pipe is usually from 4 to 10. The pipe surface shoule be smooth, no collapse, no cracks, no delamination, and no lap welding defects exist. The wall thickness is not allowed to over the deviation, no scratches, no weld dislocation, no burns and scarring and other minor defects.

Welded steel pipe should perform mechanical test, flattening test and flaring test to achieve the standard requirements. 2.5 Mpa internal pressure test is allowed to keep over 1 minue without leakage. It allows use eddy current testing method instead of the hydrostatic test. After the eddy current testing, welded steel pipe will be cut to a predetermined length by flying saw and then flip-off from the assembly line. Then both ends of the pipe should be flat head chamfering, painting, marking and hexagonal packing before delivery.