Certificate of Authority № 5CT-1300 (American Petroleum Institute) to use the Original API Monogram – manufacture of coupling stock Group1, H40/PSL 1, J55/PSL 1, K55/PSL 1, N80(1)/PSL 1 and N80(Q)/PSL 1, Group-2, L80(1)/PSL 1, Group-3, P110/PSL 1; manufacture of seamless casing or tube plain end Group-1, H40/PSL 1, J55/PSL 1, K55/PSL 1, N80(1)/PSL 1 and N80(Q)/PSL 1 , Group-2, L80(1)/PSL1