Ensuring the integrity of protective coatings is crucial—especially in industries like oil and gas, where corrosion can cause serious failures. Among several quality control measures, holiday detection is a key step in verifying the effectiveness of coatings after application. Using advanced tools like the DeFelsko Holiday Detectors, inspectors can quickly identify and address coating flaws that would otherwise lead to premature corrosion.
What is Holiday Detection?
Holiday detection is a non-destructive testing method used to locate small coating defects—such as pinholes, voids, or thin spots—that expose the underlying metal. These flaws, called holidays, may not be visible to the naked eye but can become corrosion hotspots if left unaddressed.
Using a holiday detector, a charged electrode is passed over the coated surface. If a defect is present, the electrical current passes through the holiday to the conductive substrate beneath, completing a circuit and triggering an audible and/or visual alarm. Depending on the coating thickness, either low-voltage (wet sponge) or high-voltage (dry brush or spring) methods are used in accordance with standards like ASTM G62.
Why Holiday Detection Matters
Even the smallest coating defect can compromise the protection of a pipeline or metal structure—leading to corrosion, product leakage, environmental damage, or costly downtime. Holiday detection plays a vital role in quality assurance by verifying that coatings are free from discontinuities before the structure is commissioned. It ensures that:
- The coating provides complete, defect-free coverage across the substrate.
- All holidays are identified and repaired before the asset goes into service.
- Coating integrity meets industry standards, preventing future failures.
- Long-term performance and corrosion resistance are maximized, reducing maintenance costs and extending asset life.
Voltage Matters in Holiday Detection
Choosing the correct voltage is critical. Too low, and defects may go undetected. Too high, and the coating itself could be damaged. Follow these key guidelines:
- Always refer to the coating’s Technical Data Sheet (TDS).
- Use calibrated instruments.
- Re-test after any coating repair.
Meet DeFelsko's Holiday Detection Lineup
1. PosiTest LPD – Low Voltage Pinhole Detector
Ideal for detecting flaws in thin coatings (up to 20 mils / 500 µm), the PosiTest LPD uses a wet sponge method to detect discontinuities. It’s lightweight, battery-powered, and features GroundSense™ technology to ensure proper grounding during testing.
Best for:
- Thin-film coatings
- Applications following ASTM G62 Method A
Watch PosiTest LPD in Action
See how simple it is in this short demo video. Watch on YouTube: click here.
2. PosiTest HHD & HHD C – High Voltage Holiday Detectors
Designed for thick-film coatings (≥ 10 mils / 250 µm), the PosiTest HHD and HHD C offer adjustable voltage up to 35 kV and a variety of electrode styles for different surfaces. The HHD C model uses continuous DC for improved sensitivity on thick coatings.
Features:
- Built-in voltage calculator (based on coating thickness)
- Certified voltmeter for easy verification
- Optional pinhole locators for precise defect identification
Best for:
- High-performance pipeline coatings
- Applications following ASTM G62 Method B
Watch PosiTest HHD in Action
See how simple it is in this short demo video. Watch on YouTube: click here.
Standards Compliance: ASTM G62
DeFelsko detectors comply with ASTM G62, the standard method for holiday detection in pipeline coatings. The standard defines two test methods:
- Method A – For thin coatings using low voltage and a wet sponge electrode.
- Method B – For thick coatings using high voltage and various dry electrodes.
All DeFelsko holiday detectors include a Certificate of Calibration traceable to NIST and can be verified in the field before each use.
Repair & Retesting
If a holiday is detected:
- Mark the defect using chalk or tape.
- Repair the coating following manufacturer recommendations.
- Allow the repair to cure, then retest using the same method to confirm no further defects remain.
Why Choose DeFelsko Holiday Detectors?
- Easy to use, with step-by-step guided features
- Compliant with ASTM standards
- Reliable detection across all coating thicknesses
- Calibrated and verified for field-ready use
- Backed by DeFelsko's trusted quality and support
Ready to Protect Your Coatings?
Explore the full range of DeFelsko Holiday Detectors today:
1. PosiTest LPD – Low Voltage Pinhole Detector
2. PosiTest HHD – High Voltage Holiday Detectors
3. PosiTest HHD C – High Voltage Holiday Detectors
4. DeFelsko PosiTest HHD and HHD C Verifier
Holiday Detector Distributor in Singapore
LFC PTE LTD is the authorized distributor of DeFelsko holiday detectors in Singapore. Our expert team can assist you in selecting the appropriate solutions for your needs.
Stay informed about DeFelsko products and other leading industrial inspection tools by following LFC PTE LTD on social media. You can find us on Facebook, Instagram, YouTube, and LinkedIn.
