... . Size:1/2"-40" 5. Type:Slip on flanges,Plate flanges, Blind flanges, Spectacle flanges,Lap joint flanges, Welding ... 8. Used for : petroleum,chemical,power,gas,water,linepipe, heat exchanger,shipbuilding,construction,etc. 9. Tolerance:not less than +_8% of ... thickness. 10. Production process : raw material--cutting--heating--forging--heat treatment--maching--inspection. 11. Mill ceitificate :3.1B 12. ...