Low and medium pressure boiler tubes gb3087-2008 and high pressure boiler tubes GB5310-2008 are high-quality carbon structural steel hot-rolled and cold drawn (rolled) seamless steel tubes for manufacturing superheated steam tubes, boiling water tubes of low and high pressure boilers with various structures and superheated steam tubes, large smoke tubes, small smoke tubes and arch brick tubes for locomotive boilers. Seamless steel pipe for structure (GB / t8162-2008) is a seamless steel pipe for general structure and mechanical structure. Specification and appearance quality: GB5310-2008 seamless steel tubes for high pressure boilers, the outer diameter of hot rolled tubes is 22 ~ 530mm, and the wall thickness is 20 ~ 70mm. Cold drawn (cold rolled) pipe has an outer diameter of 10 ~ 108mm and a wall thickness of 2.0 ~ 13.0mm. Special shaped seamless steel pipe is the general name of seamless steel pipe with other section shapes except circular pipe. According to the different shape and size of steel pipe section, it can be divided into equal wall thickness special-shaped seamless steel pipe (code D), unequal wall thickness special-shaped seamless steel pipe (code BD) and variable diameter special-shaped seamless steel pipe (code BJ). Special shaped seamless steel pipe is widely used in various structural parts, tools and mechanical parts. Compared with circular pipe, special-shaped pipe generally has larger moment of inertia and section modulus, and has greater bending and torsion resistance, which can greatly reduce the structural weight and save steel. (1) Gb3087-2008 seamless steel tubes for low and medium pressure boilers. The chemical composition test method shall be in accordance with the relevant parts of gb222-84 and gb223 methods for chemical analysis of iron, steel and alloy. (2) GB5310-2008 seamless steel tubes for high pressure boilers. The chemical composition test method shall be in accordance with relevant parts in gb222-84, methods for chemical analysis of iron, steel and alloy and gb223 methods for chemical analysis of iron, steel and alloy. (3) The chemical composition of imported boiler steel pipes shall be inspected according to the relevant standards specified in the contract（ 1) High quality carbon structural steel grades include 20g, 20mng and 25mng. (2) Alloy structural steel grades: 15mog, 20mog, 12crmog, 15CrMoG, 12CR2MOG, 12crmovg, 12Cr3MoVSiTiB, etc. (3) In addition to ensuring chemical composition and mechanical properties, 1Cr18Ni9 and 1cr18ni11nb boiler tubes commonly used in rusty heat-resistant steel shall be subject to hydrostatic test, flaring and flattening test one by one. Steel pipes shall be delivered in heat treated condition. In addition, there are certain requirements for the microstructure, grain size and decarburization layer of the finished steel pipe.High pressure seamless steel pipe and high pressure boiler pipe are a kind of boiler pipe, belonging to the category of seamless steel pipe. The manufacturing method is the same as that of seamless pipe, but there are strict requirements for the steel grade used in the manufacture of steel pipe. High pressure boiler tubes are often used under high temperature and high pressure conditions. High pressure boiler tubes are mainly used to manufacture superheater tubes, reheater tubes, air ducts, main steam tubes, etc. of high-pressure and ultra-high-pressure boilers.