GB/T9711-2011 PSL2 standard specifies the manufacturing requirements for seamless steel tubes and welded steel pipes for products for pipeline systems for the oil and gas industry.GB/T9711-2011 PSL2 standard applies to the seamless use of oil and gas pipeline and welded steel pipe,GB/T9711-2011 PSL2 standard applies to fine grain killed steel.GB/T9711-2011 PSL2 L555,L485,L450,L415,L390 and so on.