... national standards,such as GB / T6402-91, JB4730-2000 and JB / T5000.8-1998, or international standard.1. ... dimesions: diameter ≤1800mm, length ≤15meters and per piece ≤70Tons,2. process: forging,rough machining,heat ... technology required, and final machinig.3. provide certification: DT,UT,MT,PT, tensile test, yeild test, impact test and metallographic test, or inspection ...