scope:

This standard describes a procedure for determining shop or field conformance to a specified coating dry film thickness (DFT) range on ferrous and non-ferrous metal substrates using nondestructive coating thickness gages (magnetic and electronic) described in ASTM D 7091. 

The procedures for adjustment and measurement acquisition for two types of gages: "magnetic pull-off" (Type 1) and "electronic" (Type 2) are described in ASTM D 7091. 

This standard defines a procedure to determine whether dry coatings conform to the minimum and the maximum thickness specified. See Note 11.1 for an example of a possible modification when measuring dry film thickness on overcoated surfaces. 

This document is not intended to prescribe a frequency of coating thickness measurement for a coating failure investigation¹. 

This document contains the following non-mandatory appendices:

Appendix 1 - Numerical Example of Average Thickness Measurement

Appendix 2 - Methods for Measuring Dry Film Thickness on Steel Beams (Girders)

Appendix 3 - Methods for Measuring Dry Film Thickness for a Laydown of Beams, Structural Steel, and Miscellaneous Parts after Shop Coating

Appendix 4 - Method for Measuring Dry Film Thickness on Coated Steel Test Panels

Appendix 5 - Method for Measuring Dry Film Thickness of Thin Coatings on Coated Steel Test Panels that Have Been Abrasive Blast Cleaned

Appendix 6 - Method for Measuring the Dry Film Thickness of Coatings on Edges

Appendix 7 - Method for Measuring Dry Film Thickness on Coated Steel Pipe Exterior

Appendix 8 - Examples of the Adjustment of Type 2 Gages Using Shims

This standard is not intended to be used for measurement of thermal spray coatings. The thickness measurement procedures for these coatings are described in SSPC-CS 23.00².

¹ The number and location of measurements during a coating failure investigation may be more or less frequent than described by this standard.

² CS 23.00/AWS C2.23M/NACE No. 12, Specification for the Application of Thermal Spray Coatings (Metallizing) of Aluminum, Zinc, and Their Alloys and Composites for the Corrosion Protection of Steel is available online at