NK Ship Class is a ship classification society. It is also known by the brand name “ClassNK” or often in the industry as just “NK”. It is a not for profit society dedicated to ensuring the safety of life and property at sea, and the prevention of pollution of the marine environment.NK ship class main steel grade:NK A B D E,AH32,AH36,AH40,EH40,DH36,EH36 and so on.