A Non-polluting Option Using Cathodic Protection for Hydrostatic Testing of Petroleum Tanks with Seawater

Abstract

Oil storage tanks and derivatives must be evaluated by hydrostatic testing for leaks in sideways welds, possible cracks and failures that may have occurred during construction. Also in this test are observed defects and cracks in the concrete foundations that support the tank on the ground. The use of seawater as a fluid for hydrostatic testing in storage tank is economically attractive when the storage tanks are located near the sea. Due to its corrosive nature, seawater can cause damage to the internal surface of storage tanks. Generally, corrosion inhibitors and biocides are added to seawater in order to keep the corrosion rate under control. The disposal of water used in hydrostatic testing can represent an environmental problem whereas most corrosion inhibitors are toxic. Hydrostatic tests were run on bench scale tanks to investigate the efficiency of cathodic protection. These tests indicated that an aluminum anode (sacrificial anode) can efficiently replace corrosion inhibitors in storage tanks with the advantage that this corrosion protection system is not hazardous to the environment, as corrosion inhibitors can eventually be. The fixing of anodes in rubber floats and tubular modules represent a major innovation in the inner protection of tanks during the hydrostatic test with sea water.