ASTM G12-83(1998)

Standard Test Method for Nondestructive Measurement of Film Thickness of Pipeline Coatings on Steel

SCOPE
1.1 This test method describes the nondestructive measurement of the thickness of a dry, nonmagnetic coating applied to the external surface of steel pipe. The method is recommended for coating thicknesses up to 6 mm (0.240 in.) and for any diameter pipe, but not smaller than 10 mm (0.5 in.). It does not apply to excessively soft films.  
1.2 The values stated in SI units to three significant decimals are to be regarded as the standard.  
1.3 This standard does not purport to address all of the safety problems, if any, associated with its use. 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.
WITHDRAWN RATIONALE
This test method describes the nondestructive measurement of the thickness of a dry, nonmagnetic coating applied to the external surface of steel pipe. The method is recommended for coating thicknesses up to 6 mm (0.240 in.) and for any diameter pipe, but not smaller than 10 mm (0.5 in.). It does not apply to excessively soft films.
Formerly under the jurisdiction of Committee D01 on Related Coatings, Materials, and Applications, this test method was withdrawn in March 2007 in accordance with section 10.5.3.1 of the Regulations Governing ASTM Technical Committees, which requires that standards shall be updated by the end of the eighth year since the last approval date.

General Information

• Status: Historical
• Publication Date: 09-Jul-1998
• Withdrawal Date: 20-Mar-2007
• ICS: 87.040 - Paints and varnishes
• Technical Committee: D01 - Paint and Related Coatings, Materials, and Applications
• Drafting Committee: D01.48 - Durability of Pipeline Coating and Linings

Relations

• Replaced By: ASTM G12-07 - Standard Test Method for Nondestructive Measurement of Film Thickness of Pipeline Coatings on Steel
• Effective Date: 01-Jul-2007
• Referred By: ASTM G18-07(2020) - Standard Test Method for Joints, Fittings, and Patches in Coated Pipelines
• Effective Date: 10-Jul-1998
• Referred By: ASTM G6-07(2020) - Standard Test Method for Abrasion Resistance of Pipeline Coatings
• Effective Date: 10-Jul-1998
• Referred By: ASTM G10-10(2019) - Standard Test Method for Specific Bendability of Pipeline Coatings
• Effective Date: 10-Jul-1998
• Referred By: ASTM A950/A950M-11(2023) - Standard Specification for Fusion-Bonded Epoxy-Coated Structural Steel H-Piles and Sheet Piling
• Effective Date: 10-Jul-1998
• Referred By: ASTM G8-96(2019) - Standard Test Methods for Cathodic Disbonding of Pipeline Coatings
• Effective Date: 10-Jul-1998
• Referred By: ASTM G95-07(2021) - Standard Test Method for Cathodic Disbondment Test of Pipeline Coatings (Attached Cell Method) (Withdrawn 2024)
• Effective Date: 10-Jul-1998
• Referred By: ASTM G20-10(2019) - Standard Test Method for Chemical Resistance of Pipeline Coatings
• Effective Date: 10-Jul-1998
• Referred By: ASTM A972/A972M-00(2021) - Standard Specification for Fusion Bonded Epoxy-Coated Pipe Piles
• Effective Date: 10-Jul-1998
• Referred By: ASTM G42-11(2019)e1 - Standard Test Method for Cathodic Disbonding of Pipeline Coatings Subjected to Elevated Temperatures
• Effective Date: 10-Jul-1998
• Referred By: ASTM D6676/D6676M-21 - Standard Test Method for Cathodic Disbonding of Exterior Pipeline Coatings at Elevated Temperatures Using Interior Heating
• Effective Date: 10-Jul-1998
• Referred By: ASTM G9-07(2020) - Standard Test Method for Water Penetration into Pipeline Coatings
• Effective Date: 10-Jul-1998
• Referred By: ASTM A899-91(2021) - Standard Specification for Steel Wire, Epoxy-Coated
• Effective Date: 10-Jul-1998
• Referred By: ASTM D5498-12a(2018) - Standard Guide for Developing a Training Program for Personnel Performing Coating and Lining Work Inspection for Nuclear Facilities
• Effective Date: 10-Jul-1998
• Referred By: ASTM G14-04(2018) - Standard Test Method for Impact Resistance of Pipeline Coatings (Falling Weight Test)
• Effective Date: 10-Jul-1998

Standards Content (Sample)

NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
Contact ASTM International (www.astm.org) for the latest information
Designation:G12–83 (Reapproved 1998)
Standard Test Method for
Nondestructive Measurement of Film Thickness of Pipeline
Coatings on Steel
ThisstandardisissuedunderthefixeddesignationG 12;thenumberimmediatelyfollowingthedesignationindicatestheyearoforiginal
adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.Asuperscript
epsilon (e) indicates an editorial change since the last revision or reapproval.
1. Scope use. It shall be designed so that variations in magnetic flux or
magneticattractionbetweenitsdetectionunitandthesteelbase
1.1 This test method describes the nondestructive measure-
can be calibrated to indicate the thickness of the coating
ment of the thickness of a dry, nonmagnetic coating applied to
material.
the external surface of steel pipe. The method is recommended
4.2 It shall be suitable for measuring thicknesses of dry,
for coating thicknesses up to 6 mm (0.240 in.) and for any
nonmagnetic coatings on either a flat or a circular base.
diameter pipe, but not smaller than 10 mm (0.5 in.). It does not
apply to excessively soft films.
5. Standardization of Instruments
1.2 The values stated in SI units to three significant deci-
5.1 The instrument shall be standardized in accordance with
mals are to be regarded as the standard. The values given in
the manufacturer’s instructions before use by employing suit-
parentheses are for information only.
able thickness standards. The standardization shall be checked
1.3 This standard does not purport to address all of the
at frequent intervals during use.
safety concerns, if any, associated with its use. It is the
5.2 Nonmagnetic standards of uniform thickness are avail-
responsibility of the user of this standard to establish appro-
able in either of two types, foil or coated substrate, as supplied
priate safety and health practices and determine the applica-
or recommended by the manufacturer of the instrument.
bility of regulatory limitations prior to use.
5.2.1 Foils (Shims)—The thickness of the foil should be as
2. Summary of Test Method close as possible to the expected thickness of the coating to be
measured. The foil should be placed on a smooth, clean,
2.1 The coating thickness is determined by an instrument
low-carbon, steel plate, making certain that there is intimate
thatmeasuresthicknessbynondestructivetechniques,basedon
contact between the foil and the substrate. It is recommended
variations in magnetic flux or magnetic attraction between its
that single foils of proper thickness be used and that foils be
detection unit and the magnetic base material.
replaced frequently, since they are subject to indentation. Foils
3. Significance and Use
are advantageous for standardizing on curved surfaces and are
often more readily available than coated standards.
3.1 Measurements of film thickness are an essential part of
most ASTM test methods related to coatings on steel pipe.
NOTE 1—For some instruments there is an effective depth of penetra-
Adequate thickness is important for a coating to fulfill its
tion of the field created by the instrument probe. This is the critical depth
function of preventing or mitigating corrosion of steel pipe- of thickness at which the instrument will no longer be affected by
increases of substrate thickness. Since it depends on the instrument and
lines.
substrate, it should be determined experimentally.
3.2 The accuracy of the thickness measurements may be
influenced by the deformability of the coating. This test 5.2.2 Coated Substrate Standards —These standards con-
method is not applicable to coatings that would be readily sist of nonmagnetic coatings of known thickness permanently
deformable under the force exerted by the probe of the bonded to a low-carbon steel (1010 grade) substrate, 8 mm
measuring instrument. (0.30 in.) thick. The thickness standard should be as close as
possible to the expected thickness of the coating to be
4. Apparatus
measured.
4.1 The apparatus shall be a nondestructive-type thickness
NOTE 2—If the curvature of the coating to be measured is sufficient to
gage capable of being standardized over its range of intended
preclude standardization on a flat surface, the standardization should be
done with a standard foil on a substrate with the same curvature as the
coating to be measured.
This test method is under the jurisdiction of ASTM Co
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