Holiday
Holiday turns up in 4 fields: corrosion, powder coating, waterproofing, hydrography. Here is what it means to the people in each one.
Holiday in corrosion
Pinhole, void or bare spot in a coating that leaves the metal underneath exposed.
A gap in a coating that lets the electrolyte reach bare steel: pinholes, missed spots, very thin areas, mechanical damage or cracks. On buried and immersed structures, holidays are where corrosion and CP current concentrate, so coatings are tested 100 percent with holiday detectors before burial or service. Each holiday found is marked, repaired with a compatible patch material and retested.
"Found six holidays on the field joints, mark them with chalk and get the repair kit out."
Holiday in powder coating
A skip, void or pinhole in the coating where bare metal is exposed.
Holidays include missed spots in Faraday areas, pinholes and thin patches. On pipeline and rebar coatings they are hunted with a holiday detector: a low-voltage wet sponge for thinner films or a high-voltage spark tester for thicker ones, which sounds an alarm where the coating is breached. Holidays are marked and patched before the part ships.
"Jeep the whole joint, I want every holiday marked before backfill."
Holiday in waterproofing
A gap, pinhole or thin spot in a membrane or coating where it fails to cover the substrate.
Holidays come from missed areas, pinholes over bugholes, outgassing, skips at overlapping passes and roller drag. Small as they are, each one is a leak path. On fluid-applied membranes inspectors look for them by eye, with wet film gauges and with spark testers on conductive substrates. Holidays are marked and recoated before protection goes on.
"Spark tester found three holidays at the drain bowls, mark them in paint and hit them with another coat."
Holiday in hydrography
A gap in survey coverage where no data was collected, which must be filled before the survey is complete.
An empty patch in coverage, larger than the specification allows, where the sonar never saw the seabed. Holidays come from steering off line, swaths narrowing in shoal water, dropouts and obstacles. Processors find them on the daily coverage plot or with automated tools on the grid, and they are cleared with infill lines. Painters use the same word for a patch of wall the brush missed.
"Two holidays at the north end where the kelp shut the outer beams down, put them on tomorrow's list."