Theory Drilling depth 1000m Outer diameter 89mm Inner diameter 77.8mm Length 3m/10ft; 1.5m/5ft Raw Material steel grade 30CrMnSia/XJY850 Standard GB/T816-2008 Treatment Heat treatment the whole pipe Tensile strength £¨MPa£© 1020 yield strength £¨MPa£© 915 Elongation after Ultimate strength % 16 Surface hardness(Brinell) 270~295 Eccentricity (Radial run-out) %10 of pipe thickness