Low voltage holiday detection also known as the wet sponge technique is used to test relatively thinly coated substrates.
Nace high voltage holiday testing.
These units are used to test thick film coatings such as those used by raven applicators.
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.
There are other standards you might refer to for holiday testing besides nace sp0188.
When a holiday is encountered current flows from the electrode into the substrate.
Low voltage and high voltage holiday detectors.
This standard is intended for reference in coating specifications or other documents and may be used by specifiers applicators and coating inspectors if a specification requires holiday detection on conductive substrates.
There are several industry standards regarding holiday testing including astm d 4787 d 5162 and nace rpo 188 88.
The current returns to the detector through the ground earth wire completing the circuit and triggering audible and visible alarms.
Available for download.
Low voltage holiday detectors.
There are two main types of holiday testing devices.
Nace tm0384 holiday detection of internal tubular coatings of less than 330 μm 13 mils dry film thickness.
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.
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.
Low voltage wet sponge testers and high voltage spark testers.
Nace standards rp0188 hd1990 sg discontinuity holiday testing of protective coatings hd1990.
Types of holiday testing devices.
High voltage testers produce up to 40 000 volts of pulsed dc current.
A high voltage holiday test is performed by moving a charged electrode over the coated surface.
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.
This standard provides procedures for low voltage wet sponge testing and high voltage spark testing of new coatings on conductive substrates.
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.
They are effective for coating thicknesses of 500.
