What is a Spark Leak Detector (Holiday Detector)？

A spark leak detector (also called a holiday detector) is an instrument specially used to detect pinholes, cracks, holidays, thin spots or damage in anti-corrosion coatings on metal surfaces.

• The metal substrate is conductive.
• The anti-corrosion coating (epoxy, rubber, asphalt, FRP, PE coating, etc.) is insulative.
• The detector applies high voltage to the scanning probe.
• When the probe passes over a defect in the coating, the high voltage breaks down the air gap, creating visible sparks and triggering an audio-visual alarm.

It is widely used for non-destructive testing of insulated protective layers on:

• Buried oil and gas pipelines
• Storage tanks (inner and outer walls)
• Steel structures, ship hulls, offshore platforms
• Rubber or glass flake linings
• Plastic or coated pipes and fittings

• Ultrasonic flaw detector: Detects internal defects in metals (cracks, inclusions, porosity, weld flaws).
• Spark leak detector: Detects surface coating defects (pinholes, holidays, scratches, missing coating).