GB/T 7991.6-2014 "Test methods for vitreous and porcelain enamels—Part 6: High-voltage test" specifies the high-voltage test method for vitreous enamel coatings. It is applicable to equipment with a test voltage not lower than 2 kV and a vitreous enamel coating thickness not less than 660 μm. A direct current high voltage is applied to the vitreous enamel coating using a high-voltage generator, and a probe is used to scan the surface. Defects such as pinholes or cracks will cause breakdown and trigger an alarm. The test requires a DC high-voltage generator, a specialized high-voltage probe for vitreous enamel coatings, and a leakage current monitor. This method is used to detect defects like pinholes and cracks in vitreous enamel coatings, ensuring the integrity of equipment in corrosive environments.