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1.1 This test method describes a shop or field procedure for determination of roughness characteristics of surfaces prepared for painting by abrasive blasting. The procedure uses a portable skidded or non-skidded stylus profile tracing instrument. The measured characteristics are: Rt and Rpc. Additional measures of profile height (Rmax and/or Rz) may also be obtained as agreed upon by purchaser and seller. (The digitally-determined profile parameters Rt, Rmax, Ry and Rzlmax are extremely similar in definition.)

1.2 The values stated in SI units are to be regarded as the standard. The values given in parentheses are for information only.

1.3 In general, this method should be limited to the measurement of surface roughness where Rt is in the range 10 to 150 μm (0.4 to 6 mil) and where the Peak Count, Rpc is less than 180 peaks/cm (450 peaks/in.).

1.4 SSPC standard SSPC-PA 17 provides additional guidance for determining conformance with surface profile requirements.

1.5 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.

1.6 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

5.1 This method may be useful in assuring conformance of a prepared surface to profile requirements specified by the manufacturer of a protective coating.

5.2 This method includes determination of the peak density (number of profile peaks in a specified distance). Some workers in the field believe that optimizing peak height and peak density can improve coating adhesion.

5.3 This method allows specifiers to objectively define surface texture after abrasive blast cleaning rather than using subjective terms such as “angular pattern” or “dense and uniform pattern.”

5.4 Because implicit and explicit definitions of “roughness” may differ substantially, numerical characterizations of profile cannot be compared directly across different methods.