What the Test Finds

Pinholes, voids and other discontinuities can create direct paths to the substrate. Their significance is especially high in immersion, containment or aggressive-service linings.

Low-Voltage and High-Voltage Methods

Method selection depends on the coating type, thickness, substrate and governing procedure. Thin-film systems may use a low-voltage wet-sponge method; thicker linings may require high-voltage spark testing. Voltage must be established by the approved standard and manufacturer guidance.

Timing and Cure

Testing too early can damage an insufficiently cured film. Testing after contamination or service exposure can complicate results. Confirm cure, cleanliness, grounding and test timing before beginning.

Define the Procedure Before Work

The inspection plan should state the applicable standard, equipment, calibration or verification, voltage-setting method, coverage pattern, acceptance criteria and repair sequence.

Mark, Repair and Retest

Detected areas should be marked without contaminating the surface, repaired with an approved procedure and retested after the required cure. Records should identify locations and final acceptance.

Use Qualified Personnel

High-voltage equipment and conductive environments introduce hazards. Testing should be performed by trained personnel under the project safety and quality requirements.