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. API spiral steel pipe ... There are four steel grades (J55, K55,N80, L80 and P110), two categories (nonupset and external upset) and six sizes ... prestressed anti-hydrogen one and high-vacuum one)and three sizes (41/2 ", 31/2 " and small caliber) ...