Measurement of Surface Roughness of Abrasive Blast Cleaned Metal Surfaces Using a Portable Stylus Instrument ASTM D7127

Scope:

This surface roughness test outlines a field procedure for determining the roughness characteristics of surfaces that have been abrasively blasted in preparation for painting. A portable skidded or non-skidded stylus profile tracing equipment is used for performing the ASTM D7127 test method. The measured characteristics are R_t and R_pc. Additional measures of profile height (R_max and/or R_z) may also be obtained as agreed.

Procedure:

In the ASTM D7127 test method, an initial trace measurement was obtained, followed by four subsequent trace measurements in the compass directions from the original measurement and around 3 cm (1 in.) away for a total of 5 traces, avoiding surface imperfections. If the stylus was unable to make a complete trace due to physical hindrance, such as a deep scrape on the surface, the instrument should be moved to a nearby area away from the evident flaw and the tracing should be redone. The ten parameters generated from these five traces are recorded (2 parameters per trace). The five-measurement average for each of the two parameters was calculated as a result of this (R_t and R_pc).

Video 01: Dry vs. Wet Blast Surface Roughness on Stainless Steel

Data:

The data stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.

Conclusion:

This ASTM D7127 test method describes the proper use of a portable stylus surface roughness measuring device to evaluate particular surface parameters and determine their acceptability for applying the chosen coating on a surface that has been prepared by abrasive blasting or other mechanical techniques.