Vacuum Box Testing
This method examines whether there is leakage in the weld section between the two sheets or not. Firstly, the soap foam is sprayed onto the surface, then the box covered by transparent polymeric or glassy material is located and vacuum is created by compressor. In case of being any imperfection or gap between sheet metals, there will be a air flow which make bubbles in the foam of soap so, the gaps can be seen by inspector.