Sacrificial anode material embedded in heavy oil transmission pipeline

As the temperature increases, the corrosion rate of aluminum alloy and zinc alloy as sacrificial anode materials increases, the actual capacitance and current efficiency decrease, the consumption rate increases, and the service life decreases. At 80°C, the corrosion rate and consumption rate of aluminum anode are lower than those of zinc anode, the coupling current is larger, and the cathodic protection effect is more significant, while the working potential of zinc anode at 80°C is higher than the minimum protection potential, Does not meet the requirements of the GB/T 21448-2017 standard. Aluminum alloys are more suitable as sacrificial anode materials for high temperature heavy oil pipelines than zinc alloys.

Chemical composition of aluminum alloy anode

Chemical composition of aluminum alloy anode

At present, the commonly used sacrificial anode materials are aluminum alloy, zinc alloy and magnesium alloy. Magnesium anodes are not suitable for long-life sacrificial anodes under the insulation layer of high-temperature heavy oil pipelines because of their low current efficiency, fast consumption, and easy hydrogen evolution and spark induction. Therefore, the applicability of different anode materials under high temperature conditions was comprehensively discussed through corrosion test, constant current accelerated test and coupling performance test. The selected aluminum alloy anode and zinc alloy anode are suitable anode materials for protecting heavy oil pipelines.