API 5CT oil casing and tubing 1. Standard: API 5CT 2. Grade: J55, K55, N80, L80, C90, C95, P110 3. Casing : 4.5"-20 ... " API 5CT casing oil ... --0.514 in Thread: BTC, LTC, STC Standard: API 5CT Steel Grade: J55 K55 N80 L80 P110 C90, T95 20# and so ...