ASTM D4417 – Standard Test Methods for Field Measurement of Surface Profile of Blast Cleaned Steel
Description:
Significance and Use
5.1 The height of surface profile has been shown to be a factor in the performance of various coatings applied to steel. For this reason, surface profile should be measured prior to coating application to ensure conformance of a prepared surface to profile requirements specified by the manufacturer of a protective coating or the coating job specification.
Note 2: The peak count/peak density has been shown to be a factor in the performance of various coatings applied to steel. According to research performed by Roper, Weaver and Brandon6, an increase in peak count can improve the adhesion of some coatings to the prepared steel, as well as provide greater resistance to corrosion undercutting once the coating becomes damaged in service.
Note 3: Optical microscope methods serve as a referee method for surface profile measurement methods A and B. Profile depth designations are based on the concept of mean maximum profile (h max); this value is determined by averaging a given number (usually 20) of the highest peak to lowest valley measurements made in the field of view of a standard measuring microscope. This is done because of evidence that coating performance in any one small area is primarily influenced by the highest surface features in that area and not by the average roughness.7
Scope
1.1 These test methods cover the description of techniques for measuring the profile of abrasive blast cleaned surfaces in the field, shop, and laboratory. There are other techniques suitable for laboratory use not covered by these test methods.
1.2 Method B may also be appropriate to the measurement of profile produced by using power tools.
Note 1: The Method B procedure in this standard was developed for use on flat surfaces. Depending on the radius of the surface, the results could have greater variability with lower values and averages.
1.3 SSPC standard SSPC-PA 17 provides additional guidance for determining conformance with surface profile requirements.
1.4 The values stated in SI units are to be regarded as the standard. The values given in parentheses are for information only.
ASTM D4414