... SPEC 5CT ,Specification for casing and tubeGB/3087 steel pipe of low and middle or high preesure boiler ,GB ... ,DIN and so onUsageLow and pressure fluid transportation pipe line,casing pipe and casing tube ,boiler and oil or water ... pipe,petroleum and natural gas industry,chemical industry,electric ... , to establish a good business relationship. API 5L Gr.B steel pipe