Special seamless steel pipe factory for ship , project , machine part and so on .Materials and standard is api 5l gr.B /astm a106 gr.B /astm a53 gr.B/ gost8732 ct20/gost8731 ct20 /gost8732 ct45 /stpg370/din 1629 st44/st52/s355/s235/s275/q345 /astm a53 gr.B/ gost8732 ct20/gost8731 ct20 /gost8732 ct45 /stpg370/din 1629 st44/st52/s355/s235/s275/q345