1.　Ship pipesGB5213-85 is a carbon steel seamless pipe used for creating Class I and Class II pressure resistant piping systems, boilers, and superheaters for ships. The working temperature of carbon steel seamless pipe wall shall not exceed 450 ℃, and the working temperature of alloy steel seamless pipe wall shall exceed 450 ℃.　2.　GB5312-1999(Seamless carbon steel and carbon manganese steel pipes for ships)Mainly used for Class I and II pressure resistant pipes for ship boilers and superheaters. The representative materials are 360, 410, 460 steel grades, etc.3. Formula for calculating the weight of steel pipes: [(outer diameter wall thickness) * wall thickness] * 0.02466=kg/meter (weight per meter)