... "GB699-1999".The surface is without bubble,flaw,scab,crack,impurity and obvious scarification,it can't be have layer.The ... → (5).scrap edge → (6).forming → (7).nubbincutoffmachi → (8).burring → (9).checking(without cinc mark or burrs or others) → (10).finish(galvanized) → (11 ... more torque 20N.m, welded to withstand tensile strength over 5N.6. Surface can be galvanized and so on. Applied Range of ...