Simulation of DC stray current interference on a cathodically protected pipeline and application of mitigation methods

Laboratory (lab) simulation is a suitable method to apply theoretical principles in order to identify effective parameters in stray direct current (DC) influenced corrosion. Simulation techniques can be utilized for various mitigation methods applied in a small scales for selection of the most efficient method with regards to field applications. In this research, laboratory simulation of potential fluctuations caused by DC stray currents on a cathodically protected pipeline was investigated. A lab model capable of generating DC static and dynamic stray currents and simulating its effects on cathodically protected samples were developed. Stray current pick-up and discharge areas on an influenced structure were simulated by inducing fluctuations in the coupon stationary potential (cathodic protection (CP) potential), which normally happens as a dynamic stray current interference. An equivalent electrical circuit was also developed for the lab model. Mitigation methods for DC stray current interference on buried structures such as application of both sacrificial anodes as preferred discharge point for DC stray current and potential controlled cathodic protection system (namely intelligently controlled CP for structures with induced DC dynamic potentials) were investigated. Results showed that the latter technique could decrease interference more effectively and to a larger degree than that of the former one.