Holiday Detection of Internal Tubular Coatings of Less Than 330 μm (13 mils) Dry-Film Thickness
|Publication Date:||12 February 2016|
This NACE standard provides a nondestructive test method for the detection of holidays in a nonconductive coating film that has been applied to the inner wall (bore) of oilfield tubular goods. The apparatus and the recommended procedure for performing the test are described, as are methods of reporting the test data.
This test method applies to coatings that have a specified maximum dry-film thickness of 330 μm (13 mils). It is valid for coatings that have not been in service or previously tested with a salt solution. When holiday testing is performed on coatings that have been in service or that have been previously tested for holidays with a salt solution, there is a possibility of misleading results arising from surface contamination or salt bridging. The coating surface shall be free of materials that give added electrical insulation or that may mechanically damage the coating during the test.
This test method is not intended to provide a means of predicting the service life or service performance of these coatings.
A "holiday" is defined as a discontinuity in a protective coating that exposes unprotected surface to the environment. For the purposes of this test method, it means an area in an applied nonconductive coating that exhibits electrical conductivity when exposed to a known impressed voltage.
The specified resistance for holiday detection is 80,000 Ω ± 10% when measured between the wet probe sponge and the metallic tubular good