1. Pipe fitting appearance inspection: Generally, it is mainly observed by naked eye, sometimes with 5-20 times magnifying glass. Used to find surface defects of welded elbows.
 
2. Non-destructive testing: detection of slag inclusion, pores, cracks and other defects hidden in the weld. At present, it is common to use x - ray inspection, ultrasonic inspection and magnetic inspection.
 
3. Hydrostatic test and air pressure test: for the pressure container requiring tightness, it can detect the tightness and pressure capacity of the weld.