Critical Pitting Temperature

This test involves determining the temperature at which initiation of localised corrosion occurs. It is performed using a Gill AC with the optional CPT box plugged into a small connector on the back. The CPT box accepts a thermocouple input and controls a mains powered heater. The basis of this simple test is to hold the test sample at a required anodic potential using the Gill AC. The temperature is then increased in steps by the Gill AC until the current recorded by the Gill AC reaches a set current this temperature being the critical pitting temperature.

A typical temperature current graph from the equipment above is shown in the diagram below.

This can then be repeated at different chloride levels pHs etc to obtain a graph of critical pitting temperature versus the altered parameter for example:-