Types of holiday testing devices.
Nace high voltage holiday testing.
Sp0188 2006 formerly rp0188 discontinuity holiday testing of new protective coatings on conductive substrates available for download provides a procedure for electrical detection of minute discontinuities in coating systems that are liquid applied to conductive substrates other than pipelines.
High voltage spark test equipment is generally used for determining the existences of discontinuities in coating films having a total thickness of greater than 0 5 mm 20 mil.
These units are used to test thick film coatings such as those used by raven applicators.
This standard provides procedures for low voltage wet sponge testing and high voltage spark testing of new coatings on conductive substrates.
There are several industry standards regarding holiday testing including astm d 4787 d 5162 and nace rpo 188 88.
For example nace rp0274 guides the use of high voltage electrical inspection for pipeline coatings and nace rp0490 is the holiday detection of fusion bonded epoxy pipeline coatings from 10 to 30 mils.
There are other standards you might refer to for holiday testing besides nace sp0188.
There are two main types of holiday testing devices.
High voltage testers produce up to 40 000 volts of pulsed dc current.
4 4 coatings that are applied at a thickness of less than 0 5 mm 20 mil may be susceptible to damage if tested with high voltage spark testing equipment.
The current returns to the detector through the ground earth wire completing the circuit and triggering audible and visible alarms.
Low voltage holiday detectors.
Low voltage holiday testers are used for coatings up to 20 mils dft.
When a holiday is encountered current flows from the electrode into the substrate.
Types of test equipment.
Nace tm0384 holiday detection of internal tubular coatings of less than 330 μm 13 mils dry film thickness.
Low voltage wet sponge testers and high voltage spark testers.
Low voltage and high voltage holiday detectors.
1 3 to prevent damage to a coating film when using high voltage test instrumentation total film thickness and dielectric strength in a coating system shall be considered in selecting the appropriate voltage for.
They are effective for coating thicknesses of 500.
Nace standards rp0188 hd1990 sg discontinuity holiday testing of protective coatings hd1990.
Available for download.
Nace sp0490 2007 holiday detection of fusion bonded epoxy external coatings of 250 to 760 μm 10 to 30 mil also describes both continuous dc and pulsed dc holiday detectors and also gives both a formula and voltage table approach to selecting the test voltage based on the thickness of the coating.
