Jcastillo
Chisel testing of spot welds are an acceptable qualitative method of assessing weld fusion. You have the option of pulling a nugget which provides a way of measuring spot weld nugget diameter or just stressing the joint to ensure the spot doesnt separate. After assessing the joint you can bang the joint back together with a few taps from a hammer.
Provided spot welder current is turned up to burn through the coating, satisfactory spot welds can be achieved on coated steel panels similar to that on cold rolled steel panels. If you want complete non destructive testing of your spot welds look at one of the range of ultrasonic testers.