Holiday testing, also known as “jeeping,” is a specific inspection method used in NACE coating inspections to detect any flaws in protective coatings. These flaws, called “holidays,” are tiny gaps, pinholes, or defects in the coating that can allow moisture or chemicals to penetrate and cause corrosion.
What is Holiday Testing (Jeeping)?
Holiday testing involves using a special tool called a holiday detector to check for any discontinuities in a protective coating. This tool helps inspectors ensure that the coating is completely intact and will provide the necessary protection against corrosion.
How Does it Work?
- Holiday Detector:
- A holiday detector is a device that applies a voltage to the coating. There are two main types: low-voltage (wet sponge) and high-voltage (spark) detectors.
- Low-Voltage Detector: Used for thin coatings, it involves a wet sponge connected to the detector. The sponge is wiped over the coated surface. If there’s a holiday, the detector beeps or lights up.
- High-Voltage Detector: Used for thicker coatings, it generates a spark that jumps through any gaps in the coating to the metal underneath. If a spark occurs, it indicates a holiday.
- Inspection Process:
- The inspector moves the detector over the entire coated surface.
- If the detector signals a holiday, the exact location is marked for repair.
Why it is Important
- Detecting Flaws Early: Finding and fixing holidays early prevents corrosion from starting in those small gaps.
- Ensuring Complete Protection: A fully intact coating ensures the metal surface underneath is completely protected from corrosive elements.
- Quality Assurance: Confirms that the coating application meets industry standards and specifications.
Imagine you have a balloon that you’ve painted with a protective layer. If there are any tiny holes in the paint, air can escape, causing the balloon to deflate. A holiday detector helps you find those tiny holes so you can patch them up, ensuring the balloon stays fully inflated.
Tools and Techniques
- Low-Voltage Holiday Detector:
- Used for coatings that are up to a few mils (thousandths of an inch) thick.
- The wet sponge method is simple and effective for detecting small gaps in thin coatings.
- High-Voltage Holiday Detector:
- Used for thicker coatings where the low-voltage method might not be effective.
- The high voltage creates a spark that can jump through thicker coatings to detect gaps.
By performing holiday testing (jeeping), inspectors can ensure that the protective coating is continuous and free from flaws, providing effective protection against corrosion.
