ASTM D – Download as PDF File .pdf), Text File .txt) or read online. fdhh. Task groups within both ASTM and CEN (ISO) have been doing work on existing . The ASTM practise, D provides a table of suggested test voltages for. 25 Jul ASTM D Standard Practice for Discontinuity (Holiday) Testing of Nonconductive Protective Coat_专业资料。rubber lining test.
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Link to Active This link will always route to the current Active version of the standard. For concrete surfaces, refer to Practice D Asttm Version s – view previous versions of standard.
Although a low voltage tester can be used without damaging the coating, it may also produce erroneous results. Atmospheric conditions shall also be considered since the voltage required for the spark asgm gap a given distance in air varies with the conductivity of the air at the time the test is conducted.
Deposits may also be present on the surface causing telegraphing current traveling through a moisture path to a discontinuity, giving an erroneous indication or current leakage across the surface of the coating due d55162 contamination. Solvents retained in an uncured coating film may form an electrically conductive path through the film to the substrate.
The values given in parentheses are for information only. Discontinuities in a coating are frequently very minute and not readily visible.
The degree of coating continuity required is dictated by service conditions. The allowable number of discontinuities should be determined prior to conducting this test since the acceptable quantity of discontinuities will vary depending on coating film thickness, design, and service conditions.
This practice provides a procedure for electrical detection of minute discontinuities in nonconductive coating systems. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.
Its use on a coating previously exposed to an immersion condition has often resulted in damage to the coating and has produced erroneous detection of discontinuities due to permeation or moisture absorption of the coating. Referenced Documents purchase separately The documents listed below are referenced within the subject standard but are not provided as part of the standard.
Suggested starting voltages are provided in Table 1. High voltage spark test equipment is generally used for determining the existences of discontinuities in coating films having a total thickness of greater than 0.
The use of a high voltage tester on previously exposed coatings has to be carefully considered because of possible spark-through, which will damage an otherwise sound coating. Consult the coating manufacturer for proper test equipment and inspection voltages.