Abstract
Crude oil and gas production gathering centers are facilities for separating the crude oil, gas, water, and solids in the well stream. Gas is separated from liquids by reducing the pressure. After separating the gas, the crude oil is heated and treated in a desalter unit which is used to reduce the level of salt and water in the crude. As a result, there are a large number of pipes below ground at different temperatures often running parallel to each other and crossing each other. Testing of cathodic protection systems becomes very important to the useful life of the facility.
NACE Standard RP0169 potential criteria are used to evaluate cathodic protection on buried piping. In gathering centers it is common to use copper electrical grounds to protect personnel and equipment from electrical shorts. These grounds result in mixed potentials (iron coupled with copper), which make the use of the 100 mV potential shift difficult if not impossible to use. Interpretation of potential data can be further complicated by mixed impressed current cathodic protection (ICCP) and sacrificial anode cathodic protection (SACP) systems.
