ASTM D374/D374M-23 PDF

Full title and description

Standard Test Methods for Thickness of Solid Electrical Insulation — a set of standardized procedures (Test Methods A through H) for measuring the thickness of various solid electrical insulating materials using specified micrometers, calipers and measurement techniques.

Abstract

Provides eight test methods and associated apparatus, terminology, measurement units (SI and inch-pound), calibration and uncertainty guidance for determining the thickness of solid electrical insulation materials such as elastomers, rubber, paper, paperboard, plastic films and sheets, pressboard, and polymeric films. The methods are intended for use unless otherwise required by a material specification.

General information

• Status: Active / Current standard.
• Publication date: Current edition approved October 1, 2023 (designated D374/D374M‑23).
• Publisher: ASTM International.
• ICS / categories: Insulating materials in general — ICS 29.035.01 (electrical insulating materials).
• Edition / version: D374/D374M‑23 (most recent revision).
• Number of pages: 12 pages (standard document length).

Scope

The standard covers the determination of thickness for several types of solid electrical insulating materials using recommended measurement techniques. Values are stated in both SI and inch‑pound units, which are to be regarded separately as standard; the document provides specific test methods (A–H) and guidance on apparatus selection, calibration, measurement pressure, and reporting of results and uncertainties. Use these test methods unless otherwise required by a material specification.

Key topics and requirements

• Eight specified test methods (Test Methods A through H) covering different micrometers and measurement approaches for varied materials and thickness ranges.
• Apparatus definitions and minimum instrument capability (examples include machinist’s micrometer, caliper with calibrated ratchet or friction thimble, and micrometers with specified resolution).
• Instructions on controlling measurement pressure (use of calibrated ratchet or friction thimble and calibrated spring where applicable) and recommended manipulative procedures.
• Guidance on units (SI and inch‑pound), reporting conventions, and treatment when units are not exact equivalents.
• Calibration, measurement uncertainty, specimen preparation and handling, and criteria for selecting the appropriate test method for a given material.

Typical use and users

Used by manufacturers, quality/control laboratories, test labs, material engineers and researchers working with electrical insulating materials (rubber, elastomers, paper, polymeric films, pressboard, plastic sheets) to ensure consistent thickness measurement for specification compliance, quality assurance, and product development. Often referenced in material specifications and procurement requirements.

Related standards

References and related documents cited by the standard include ASTM Terminology D1711 (Terminology Relating to Electrical Insulation) and test method E252 (Thickness of Foil, Thin Sheet, and Film by Mass Measurement), among other ASTM electrical insulation test standards and terminology documents.

Keywords

caliper, micrometer, thickness, electrical insulation, elastomers, rubber, paper, paperboard, plastic film, plastic sheet, polymeric film, pressboard, measurement uncertainty, SI units, inch‑pound units.

FAQ

Q: What is this standard?

A: ASTM D374/D374M‑23 is a set of Standard Test Methods for Thickness of Solid Electrical Insulation that specifies procedures and apparatus for measuring the thickness of a variety of solid insulating materials.

Q: What does it cover?

A: It covers eight test methods (A–H), apparatus requirements (types of micrometers and calipers), measurement technique (including control of measurement pressure), units and reporting, calibration and uncertainty guidance, and specimen considerations for measuring thickness of solid electrical insulation.

Q: Who typically uses it?

A: Manufacturers of insulating materials and electrical components, independent testing laboratories, quality/control engineers, and specification writers who need repeatable, standardized thickness measurements for compliance and product verification.

Q: Is it current or superseded?

A: The designation D374/D374M‑23 indicates the current edition approved October 1, 2023; it is the active version as of that approval. Users should verify whether any amendments or reapprovals have occurred since that date before relying on the text for regulatory or contractual requirements.

Q: Is it part of a series?

A: It is part of ASTM’s body of standards covering electrical and electronic insulating materials (Committee D09) and references related ASTM terminology and test methods; it complements other insulation test standards and terminology documents rather than forming a numbered sequential “series.”

Q: What are the key keywords?

A: Key keywords include caliper, micrometer, thickness, electrical insulation, elastomers, rubber, paper, polymeric film, pressboard and measurement uncertainty.