This Standard provides a practical test method for the on-site determination of the presence of pinholes, holidays, cracks and other discontinuities that penetrate to the substrate in a non-conductive, protective thin film coating of less than 250 µm thickness, or where metal particles protrude through the coating. This Standard is applicable to coated metal items, equipment or structures that may be subjected to long-term burial or immersion, are in continuous contact with a moist, chemically aggressive environment, and require a greater degree of protection than is normally necessary for items exposed to the atmosphere.