Holiday Testing

Introduction

holiday test is performed with a holiday detector, which is an electrical device used to determine the location of a gap or void in the coating. There are various techniques and tools available for holiday detection. Coatings applied to concrete substrates can also be tested for discontinuities using either a low-voltage or a high-voltage holiday detector, depending on the coating thickness.

A holiday test is a non-destructive test method applied on protective coatings to detect unacceptable discontinuities such as pinholes and voids. Holiday testing involves checking an electric circuit to see if current flows to complete the circuit. This testing is used to find coating film discontinuities that are not readily visible.

A holiday test is usually performed on tank interiors, chemical storage vessels and buried structures because of the importance of maintaining adequate coating protection in aggressive service environments.

A holiday test is also known as a continuity test.

Application

A low-voltage holiday test is used when the coating system is less than 500 microns (20 mils) thick. A high-voltage holiday test is used when the coating system is thicker. High-voltage holiday testing requires special care not to damage the coating or cause injury to the operator.

Holiday testing normally used in the Oil and gas industry by PRETECT for determining the general classification of ferrous materials. There are various methods of spark testing like compressed air method, bench grinder method etc. Automatic holiday testing is steadily gaining popularity though. Automatic holiday testing reduces the reliance on manual labor and there are fewer chances of mistakes. It is also faster, secure and the method giving the best results.

The wet sponge technique is a quick and simple method for testing insulation coatings less than 500 microns (20 mils) thick on conductive substrates. The Elcometer 270 Pinhole Detector provides both visual and audible alarms when a flaw is found, and it is incredibly easy to use.

Benefits