Following the principles of this standard will improve holiday detection of pipeline coatings. This standard is intended to be used by personnel in pipeline operating companies, pipeline contractors, pipeline inspection services, and pipeline coating mills.
1.1 Electrical inspection (holiday detection) is a test of the continuity of a protective coating. This type of inspection does not provide information concerning coating resistance, bond, physical characteristics, or the overall quality of the coating, nor is it intended to do so. It detects bubble or blister type voids, cracks, thin spots, and foreign inclusions or contaminants in the coating that are of such size, number, or conductivity as to lower the electrical resistance or dielectric strength of the coating significantly.
1.2 Use of a holiday detector should be at the discretion of the coating inspector. An initial holiday inspection, performed as soon after the application of the coating as practicable, serves to check the materials and the application procedures. A final coating inspection, before the coated pipe is placed in the ditch, will disclose any defect or damage to the coating, except disbanding, which has occurred during the construction period.
1.3 This standard presents acknowledged techniques in the use of holiday detector equipment currently used on pipeline coatings prior to lowering-in operations and presents a table of recommended voltages for various coating thicknesses. These recommendations do not apply to thin-film coatings (i.e., coating materials usually applied by a fusion-bonding process). Thin-film pipeline coatings are generally applied to a dry-film thickness less than 0.5 mm (20 mils). THIS PRODUCT IS SOLD AS A DOWNLOADABLE PDF ONLY.
Key words: test methods, corrosion control, inhibited acid, acid preparation, historical document
Historical Document 2004