Structural steel for hulls is divided into strength levels according to their small yield points: general strength structural steel and high strength structural steel. Ship plates refer to hot-rolled steel plates used to manufacture ship hull structures produced in accordance with the requirements of classification society construction specifications. The general strength structural steel according to the specifications of China Classification Society is divided into four quality grades: a, b, d, and e (i.e., ccsa, ccsb, ccsc, ccsd); the high-strength structural steel according to the specifications of China Classification Society is divided into three quality grades: Intensity levels, four quality levels.
The general strength A and B class ship plates can meet their process and mechanical performance requirements through ordinary rolling, so the production process is relatively simple; while the production of D, E class and high strength class ship plates requires relatively complete equipment. Under the equipment, it is realized through controlled rolling and controlled cooling process or heat treatment process. At the same time, the requirements for the inherent steel purity of the supplied steel billets are relatively high, especially the content of S, P, N, O, H, etc. in the steel must be strictly controlled.
The International Association of Classification of Shipping (IACS) is composed of the world's major ship surveying organizations. It currently has 11 formal members and 2 associated members. The official member societies are American Bureau of Shipping (ABS), Bureau Veritas (BV), China Classification Society (CCS), Det Norske Veritas (NV), Germanischer Lloyd (GL), and Korean Register of Shipping. (KR), Labor Classification Society (LR), Japan Maritime Association (NK), Polish Register of Ships (PRS), Italian Register of Ships (RINA), Russian Register of Ships (RS), contact member societies namely India Classification Society (IRS), Croatian Register of Ships (CRS). More than 95% of the total tonnage of the world's merchant ships have undergone statutory approval inspections by IACS authorized classification societies.
