This Standard specifies the carbon steel tubes (hereafter referred to as "tubes"）used for exchanging heat between the inside and outside of the tube, such as water tubes, smoke tubes, superheater tubes and air preheater tubes of the boiler, and heat exchanger tubes, condenser tubes and catalyser tubes used in chemical and petroleum industries. It is not applicable to the steel tubes for heating furnace and steel heat exchanger tubes for low temperature service.