Pressurized Atlas Cell Testing is commonly understood to be an aggressive accelerated test for lining systems due the combination of pressure, temperature and a thermal gradient across the coating film known as the Cold Wall Effect. This is especially true when Carbon Dioxide (CO2) is added to the gas phase, as CO2 is miscible with oil and soluble in water. A familiar gas mix of 5% CO2, 5% Hydrogen Sulfide (H2S), and 90% Methane (CH4) are used in test protocols to simulate head space conditions of tanks and pressure vessels in oil and gas production conditions.
The terminal is subdivided for Oil, Gas and Produced Water plants. Each of these plants has number of storage tanks. The age of the tanks varies between 15-25 years. The products held within these tanks varies, from crude oil, condensate, produced water, potable water, to off spec oil and diesel fuel.
Most of the tanks within the facility have a similar CP arrangement and design. Each tank base is protected by an impressed current grid mesh anode buried in compacted, clean, sand backfill beneath the tank base and is powered by a transformer-rectifier placed outside the bund wall or within an electrical switch room. Permanent reference electrodes are installed beneath all tank bases to enable accurate potential measurements. Reference electrodes vary from Copper/Copper Sulphate, Silver/Silver Chloride to Zinc.
Corrosion and cavitation erosion on steel structures are problems and can have a huge impact on safety and economy. In order to prevent corrosion, protective coatings can be used as a barrier between the steel surface and the corrosive elements such as seawater or various liquid cargos. However, when coating systems fail the surface will be exposed to the environment with all consequences. From that perspective, the weakest link is the coating used to protect the steel.