Manufacturing method:
(1) General GB9948 seamless steel pipe temperature is below 450℃, domestic pipe is mainly made of no. 10, 20 carbon bonded steel hot rolled pipe or cold drawn pipe.
②GB9948 seamless steel pipe is often used in high temperature and high pressure conditions, the pipe under the action of high temperature flue gas and water vapor, oxidation and corrosion will occur.The steel pipe is required to have high durable strength, high oxidation corrosion resistance and good microstructure stability.
(2) use:
(1) General GB9948 seamless steel pipe is mainly used to manufacture water-cooled wall pipe, boiling water pipe, superheated steam pipe, locomotive boiler superheated steam pipe, large and small smoke pipe and arch brick pipe.
②GB9948 seamless steel tube is mainly used to manufacture superheater tube, reheater tube, pipe, main steam pipe and so on of high pressure and ultra-high pressure boiler.
GB9948 seamless steel tube according to the high temperature performance is divided into general boiler tube and high pressure boiler tube.Whether general boiler tube or high pressure boiler tube can be divided into various steel tubes according to different requirements of its use.
Specifications and appearance quality
(1)GB3087-2008 “Seamless Steel pipe for Low and medium pressure boiler” provisions.Specifications of steel tubes for various structural boilers, diameters 10 ~ 426mm, 43 kinds in total.There are 29 kinds of wall thickness from 1.5 mm to 26mm.However, the outer diameter and wall thickness of superheated steam pipe, large smoke pipe, small smoke pipe and arch brick pipe used in locomotive boiler are stipulated otherwise.
(2)GB5310-2008 “Seamless Steel Tube for High pressure Boiler” hot rolled pipe diameter 22 ~ 530mm, wall thickness 20 ~ 70mm.Cold drawn (cold rolled) tube diameter 10 ~ 108mm, wall thickness 2.0 ~ 13.0mm.
(3)GB3087-2008 “seamless steel tube for low and medium pressure boiler” and GB5310-2008 “seamless steel tube for high pressure boiler” provisions.Appearance quality: cracks, folding, rolling, scarring, separation and wrinkles are not allowed on the inner and outer surface of the steel pipe.These defects should be eliminated completely.The clearance depth shall not exceed the negative deviation of the nominal wall thickness, and the actual wall thickness at the clearance shall not be less than the minimum allowable wall thickness.