Materials Performance

AUG 2018

Materials Performance is the world's most widely circulated magazine dedicated to corrosion prevention and control. MP provides information about the latest corrosion control technologies and practical applications for every industry and environment.

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26 AUGUST 2018 W W W.MATERIALSPERFORMANCE.COM F FEATURE ARTICLE Cathodic Protection in Arctic Conditions Study Assesses Corrosivity of the Environment at the Yamal LNG Carrier Terminal in Siberia, Russian Federation Nicolas Larché, Erwan Diler, Jean Vittonato, and Sergey Shumovskiy Editor's Note: Yamal LNG, one of the largest liquefied natural gas (LNG) projects in the world, processes natural gas from the giant onshore South Tambey gas and condensate field located on the Yamal Peninsula in the Arctic region of the Russian Federation. Yamal LNG will produce reserves of 4.6 billion bbl (731 bil- lion L) of oil equivalent. The project includes an inte- grated gas treatment and liquefaction facility with three liquefaction trains (each with a capacity of 5.5 million tons per year), storage tanks, a port with 15 ARC 7 ice-class LNG carriers with a capacity of 170,000 m 3 each, and airport infrastructure. Source: www.total.com. For most projects, cathodic protection (CP) design can be performed using CP standards or existing data from literature and feedback from the field. This was not the case for the Yamal LNG carrier ter- minal project in Sabetta (Siberia, Russian Federa- tion). This terminal is located in the Arctic between the Kara Sea and a river mouth in the Yamal Penin- sula. Here the environment experiences varying conditions in terms of salinity, temperature, and liq- uid/ice phases, which are affected by the icing and deicing seasons and water depth. During the cold season, the water's surface is ice, but it is liquid above the sea floor. Salinity varies from the surface water to deeper water, especially during the sum- mer season. Total (Paris, France) is a partner of the Yamal LNG project and has been involved in the CP design for berths at the Yamal LNG carrier terminal. Given the harsh local conditions, protecting the berths from corrosion with galvanic anodes is the preferred solution. Because the water is brackish, however, it could significantly impact a CP design using gal- vanic anodes. For this reason, obtaining accurate current density (CD) was considered a mandatory requirement to achieve efficient CP. These very specific conditions could not be sim- ulated at the laboratory scale, and required a corro- sion study with on-site measurements so the CP requirements could be determined for immersed carbon steel (CS) structures (berths and/or steel sheet piles) at the gas carrier terminal. The objectives of the study were (a) to assess the corrosivity of the environments encountered in the immersed areas of the Yamal LNG terminal and (b) to assess the specific CP requirements in these environments. These quantified results would then be used when selecting and designing an adapted corrosion protection system. Physicochemical measurements for water depth, temperature, pH, specific conductivity, and dis- solved oxygen (DO) were performed at the Yamal LNG terminal. This was done using instrumented arrays with corrosion and CP sensors that were deployed at two locations, Berths A and B. At each site, two depths were investigated: one at ~1.5 m below the water surface and one ~1.5 m above the sea floor. Additionally, laboratory experiments mea- suring corrosivity and CP at different temperatures and in solid ice were performed in Yamal LNG and Brest, France.

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