Development of martensitic stainless steel seamless pipe for linepipe application

Two types of martensitic stainless steel seamless pipes have been developed for linepipe applications. One is 0.01C-11Cr-1.5Ni-0.5Cu-0.01N steel pipe for CO sub 2 environment, and the other is 0.01C-12Cr-5Ni-2Mo-0.01N steel pipe for CO sub 2 and slight H sub 2 S environment. Both pipes are suitable for welding without preheating. They give X80 grade strength and good low temperature toughness of welds without PWHT. The former pipe gives better resistance to CO sub 2 corrosion than the 13Cr martensitic stainless steel for OCTG. The latter pipe gives good SSC resistance in 10% NaCl solution with H sub 2 S partial pressure of 0.002 MPa and pH value of 4.0. These steel pipes have a great economic benefit and are expected to substitute conventional flowline pipes using carbon steel with inhibitor injection or costly corrosion resistant materials, such as duplex stainless steel.