ASTM E376: Standard Practice for Measuring Coating Thickness by Eddy Current
Practice for using eddy current methods to measure nonmagnetic coating thickness on ferromagnetic substrates. ASTM E376 is widely used for quality control in coating applications.
ASTM International is a consensus body that publishes test methods and practices used inside other codes; ASTM E-series documents are the most widely cited NDT references in North America.
ASTM standards become enforceable when invoked by a contract, by another code such as ASME Section V, or by a regulator citing them as the controlling test method.
ASTM E376 is invoked when the scope of work matches its title — standard practice for measuring coating thickness by eddy current — and when the contract or regulatory regime cites it as the controlling document. In fabrication shops the standard is reproduced inside the written procedure book and referenced from every inspection report so that the auditor's paper trail leads back to the same paragraph the inspector worked from.
Methods covered
Industries
- Manufacturing
- Construction
- Marine
- Personnel qualification: examinations under ASTM E376 must be performed by inspectors qualified and certified to a recognised scheme (typically ASNT SNT-TC-1A, CP-189, or ISO 9712 depending on jurisdiction), with documented training hours, vision tests, and a controlling written practice.
- Written procedure: every examination requires a written, controlled procedure that names the method, equipment, calibration steps, scanning pattern, and acceptance criteria — and is qualified before first use.
- Eddy-current setup: probe selection, frequency, gain, and reference-standard calibration must be documented and verified against a reference standard with known artificial flaws prior to inspection.
- Acceptance criteria: indications are evaluated against the standard's tabulated limits (length, depth, alignment, frequency); any indication exceeding the criteria is recorded, dispositioned, and either repaired or evaluated for fitness-for-service.
- Documentation: examination reports must include enough information for a third party to reproduce the inspection — equipment serial numbers, calibration records, inspector ID, sketches of indications, and the controlling procedure revision.
ASTM standards are reviewed on a five-year cycle and either reaffirmed, revised, or withdrawn. Revisions to ASTM E376 are generally evolutionary rather than revolutionary — clarifying language, adding new technique variants, or aligning with parallel ISO documents. The standard's designation includes the year of last revision (e.g. E709-21), and contracts that name a specific year freeze the inspection requirements to that revision.
On a typical Manufacturing job, ASTM E376 is reproduced inside the inspection company's written procedure, the procedure is qualified for the customer, and each examination report cites the procedure revision back to the controlling clause of the standard.
What does ASTM E376 cover?
ASTM E376 (Standard Practice for Measuring Coating Thickness by Eddy Current) is published by ASTM International. Practice for using eddy current methods to measure nonmagnetic coating thickness on ferromagnetic substrates.
Is ASTM E376 mandatory or voluntary?
ASTM E376 is a consensus standard. It becomes mandatory when invoked by a contract, by another code that cites it (for example ASME Section V calling out an ASTM practice), or by a regulator that has adopted it into law in a specific jurisdiction.
Who is qualified to perform inspections under ASTM E376?
Inspections under ASTM E376 must be performed by personnel qualified and certified to a recognised NDT certification scheme — most commonly ASNT SNT-TC-1A or CP-189 in the United States, ISO 9712 in much of the rest of the world, and NAS 410 for aerospace work. The written practice that controls qualification must be in place before any examination is started.
Which other standards are commonly cited alongside ASTM E376?
ASTM E376 is most often cited together with the parent code that brings it into the contract — typically ASME Section V or VIII for U.S. pressure equipment, AWS D1.1 for structural welding, API 510/570/653 for in-service petroleum equipment, or the matching EN/ISO standard for European and international work.
Standard Code
ASTM E376
Organization
ASTM International
Methods Covered
1 method(s)
Industries
3 sector(s)
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