We manufacture four steel grades (J55, K55,N80, L80 and P110), six sizes (1.9", 2-3/8", 2-7/8 ", 3-1/2", 4", 4-1/2") of tube. welded round tube There are four steel grades (J55, K55,N80, L80 and P110), two categories (nonupset and external upset) and six sizes (1.9", 2-3/8", 2-7/8 ", 3-1/2", 4", and 4-1/2") of tubing.With five production lines, 70 thousand tons of tubing and 1 million pieces of ...