What Does Pneumatic Adhesion Tensile Strength Testing Instrument (PATTI) Mean?
A pneumatic adhesion tensile strength testing instrument is an apparatus used to determine the tensile adhesive strength of a coating to a surface. The typical test instrument consists of several components including a detachable loading fixture with a flat base, a central threaded grip for engaging and transferring load to the loading fixture, and a compressed gas system that acts as the energy source for applying a continuous tensile force on the loading fixture.
The tests conducted with this instrument are typically done in accordance with the ASTM D4541 - “Standard Test Method for Pull-Off Strength of Coatings Using Portable Adhesion Testers” for the purpose of ensuring adequate corrosion protection.
Corrosionpedia Explains Pneumatic Adhesion Tensile Strength Testing Instrument (PATTI)
The typical test involves first attaching the loading fixture, also called a pull-stub, to the testing surface with an epoxy resin. Once the epoxy is cured (usually after 24 hours), a piston is attached to the stub. A control module is then used to provide pressurized gas to the piston via a hose. The device operator supplies the pressurized gas in a controlled manner, thus gradually increasing the pressure until the pull-stub and the coating separate from the substrate. The pressure at separation (burst pressure) is converted to tensile strength by using a table supplied by the testing instrument manufacturer.
A series of 3 or more tests are usually performed and compared before the final pull-off strength is determined.