Standard Test Methods for Holiday Detection of Coatings used to Protect Pipelines

Abstract

5.1 Method A—Low voltage holiday detection is used to locate holidays and pinholes in thin-film coatings (up to 0.508 mm (20 mils) using a sponge wetted with tap water (and a wetting agent for coatings thicker than 10 mils). The water carries the current from the electrode through the holiday to the conductive substrate. The detector is grounded to the coated substrate. When the detector senses this flow of current it alarms. 5.2 Method B—High voltage holiday detection is used to locate holidays and pinholes in thick-film coatings (greater than 20 mils), but can be used on coatings as low as 10 mils thick. A test voltage is selected and set. A charged Electrode is placed in contact with the coating, and the Detector is grounded to the coated substrate. When Electrical Breakdown occurs, electric current flows between the Detector’s electrode and the conductive substrate and emits an audible alarm. 5.3 This standard does not apply to holiday detection of tape wraps used to protect pipe or coatings containing conductive raw materials such as conductive pigments and extenders. 5.4 The thickness of a coating applied to ductile iron pipe, fittings, or other iron castings may vary substantially due to the inherent roughness of the substrate. For these applications, consult the coating manufacturer for their recommended test voltage setting when using Method B. The coating manufacturer’s recommended test voltage setting may be subject to approval by the owner. Note 1: Use of voltage settings lower than those listed in this standard may increase the likelihood of non-detection.