STANDARD GRADE APPLICATION API 5CT J55,K55,N80 Low-Medium Pressure Fluid, Coal Gas Transportation, Heating Steam Supply, Thermoelectricity, Project Construction ,Bridge Structure, Oil And Natural Gas Pressure Steel Tube etc. API 5L GR.B,X42/X46/X52/X56/x60/X70/X80 ASTM A53 ASTM A252 ASTM A500 GR.A / GR.B / GR.C GR.1/2/3