1.1 Before welding, defects on workpiece shall be removed, defects on important positions of important workpiece shall be inspected by nondestructive inspection method and the removing scope shall be determined; after removing, methods, like magnetic particle, dye or pickling, shall be used to confirm whether the defects have been thoroughly removed.
1.2 Defects may be removed by such methods as machining, pneumatic chipping, carbon arc air gouging and grinding wheel. The big defects on workblank may be treated by gas cutting method.
1.3 When removing the defects by gas cutting or carbon arc air gouging method, the carbon steel forgings having the quench hardening tendency and other various alloy steel forgings must be preheated, and the preheating temperature is same as the that of repair welding, as detailed in Table 1.
1.4 When removing the defects by gas cutting method, to prevent crack propagation, holes shall be drilled at both ends of the crack before cutting it, and the diameter of the used bit shall be determined according to the thickness of workpiece, which generally is φ10~φ40mm. The drill hole positions shall be 10~15mm away from the crack tips. The drill hole depth shall exceed the crack depth by 3~5mm.
Contents
1 Pre-weld Preparation
2 Weld Preheating and Post-weld Heat Treatment
3 Selection and Baking of Electrodes
4 Repair Welding Process
5 Repair Welding Quality Inspection
Standard
JB/ZQ 4722-2006 Heavy Mechanical General Techniques and Standards (English Version)
1.1 Before welding, defects on workpiece shall be removed, defects on important positions of important workpiece shall be inspected by nondestructive inspection method and the removing scope shall be determined; after removing, methods, like magnetic particle, dye or pickling, shall be used to confirm whether the defects have been thoroughly removed.
1.2 Defects may be removed by such methods as machining, pneumatic chipping, carbon arc air gouging and grinding wheel. The big defects on workblank may be treated by gas cutting method.
1.3 When removing the defects by gas cutting or carbon arc air gouging method, the carbon steel forgings having the quench hardening tendency and other various alloy steel forgings must be preheated, and the preheating temperature is same as the that of repair welding, as detailed in Table 1.
1.4 When removing the defects by gas cutting method, to prevent crack propagation, holes shall be drilled at both ends of the crack before cutting it, and the diameter of the used bit shall be determined according to the thickness of workpiece, which generally is φ10~φ40mm. The drill hole positions shall be 10~15mm away from the crack tips. The drill hole depth shall exceed the crack depth by 3~5mm.
Contents of JB/ZQ 4722-2006
Contents
1 Pre-weld Preparation
2 Weld Preheating and Post-weld Heat Treatment
3 Selection and Baking of Electrodes
4 Repair Welding Process
5 Repair Welding Quality Inspection