ASTM D4787-24 PDF

Full title and description

Standard Practice for Continuity Verification of Liquid or Sheet Linings Applied to Concrete Substrates — a short practice that describes electrical continuity (holiday/discontinuity) testing procedures using high‑voltage spark testers (pulsed or continuous DC) for nonconductive liquid or sheet linings applied to concrete, with guidance on conductive underlayments and factors affecting test reliability.

Abstract

This practice (ASTM D4787‑24) provides methods to detect discontinuities such as pinholes, voids, holidays, cracks, and conductive inclusions in nonconductive linings on concrete substrates. It explains when and how to use high‑voltage spark testers (including pulsed vs continuous DC), the role of conductive underlayments (liquid primers, graphite veils, conductive fibers/screening), and limitations related to substrate conductivity, moisture, and lining cure. The practice is intended for new linings and includes safety and test‑voltage considerations.

General information

• Status: Active.
• Publication date: 2024 (Active / last updated July 15, 2024).
• Publisher: ASTM International.
• ICS / categories: 91.100.30 (Concrete and concrete products).
• Edition / version: D4787‑24 (current edition).
• Number of pages: 6 pages.

Scope

This practice covers procedures for detection of discontinuities in nonconductive liquid or sheet linings applied to concrete substrates, with or without a conductive underlayment. It addresses detection using high‑voltage spark testers (pulsed or continuous DC) and identifies discontinuities such as pinholes, internal voids, holidays, cracks, and conductive inclusions; it also notes factors affecting test performance (substrate conductivity, moisture, presence of rebar, cure time, fillers) and safety considerations.

Key topics and requirements

• Detection methods: high‑voltage spark testing (pulsed and continuous DC) tailored to lining thickness and dielectric properties.
• Use and selection of conductive underlayments (liquid conductive primers with carbon/graphite, graphite veils, conductive fibers or screening) to provide a return path where substrate conductivity is insufficient.
• Identification of discontinuity types: pinholes, holidays, voids, cracks, and conductive inclusions; guidance on appropriate test voltages and techniques to avoid damaging the lining.
• Factors influencing test reliability: concrete moisture content, presence of rebar, cement/aggregate composition, admixtures, porosity, temperature/humidity, and lining cure state.
• Restrictions and intended use: intended primarily for new linings (testing previously exposed or immersed linings can produce erroneous results or cause damage).
• Safety and calibration considerations: consider dielectric properties, adjust test voltages accordingly, and follow manufacturer recommendations for equipment calibration and sensitivity.

Typical use and users

Typical users include coating/lining applicators, quality assurance and quality control (QA/QC) inspectors, engineering consultants, facility owners/operators, and specifiers involved in waterproofing, chemical containment, and protective lining installations on concrete structures such as tanks, secondary containment, pools, decks, and industrial floors. The practice is used during installation acceptance testing and performance verification for new lining systems.

Related standards

Referenced and related practices include ASTM D5162 (discontinuity/holiday testing for nonconductive coatings on metallic substrates) and industry procedures such as NACE / AMPP guidance (e.g., NACE RP0188 / SP0188 and Test Method G62) for selecting test voltages and alternative techniques; standards and guides on leak‑locating for waterproof membranes (electronic conductance methods) may also be relevant when working with membrane systems.

Keywords

continuity verification, holiday testing, discontinuity detection, high‑voltage spark test, conductive underlayment, liquid linings, sheet linings, concrete substrates, pinholes, QA/QC, dielectric strength, ASTM D4787‑24.

FAQ

Q: What is this standard?

A: ASTM D4787‑24 is a practice that sets out procedures for electrical continuity (holiday) testing of nonconductive liquid or sheet linings applied to concrete substrates, using high‑voltage spark testers and specifying considerations for conductive underlayments and test reliability.

Q: What does it cover?

A: It covers detection methods for discontinuities (pinholes, voids, holidays, cracks, conductive inclusions) in new linings on concrete, describes use of pulsed or continuous DC spark testers, and explains factors (substrate conductivity, moisture, curing, fillers) that affect test results and selection of test voltages.

Q: Who typically uses it?

A: Coating applicators, inspectors, QA/QC teams, consultants, specifiers, and owners involved in lining and waterproofing projects on concrete structures use this practice for installation acceptance and integrity verification.

Q: Is it current or superseded?

A: Current — the active edition is D4787‑24 (2024). The practice is listed as active and last updated in 2024.

Q: Is it part of a series?

A: It is part of ASTM’s protective coatings/linings practices (Book of Standards volume covering coatings and linings) and is often used alongside other discontinuity test practices such as ASTM D5162 (metal substrates) and industry guidance from NACE/AMPP for test voltage selection and leak‑locating methods.

Q: What are the key keywords?

A: continuity verification, holiday testing, discontinuity, high‑voltage spark tester, conductive underlayment, liquid linings, sheet linings, concrete.