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Evaluation of the Effect of Welding Process on the Performance of an Inorganic Industrial Coating for Soil-side Application of Above Ground Storage Tank Bottoms

Protection of aboveground water storage tank bottom plates against soil side corrosion is an important concern for the oil and gas industry, particularly when considering long-term continuous operation requirements for these assets. Corrosion of the tank bottom plates is mainly due to the formation of galvanic corrosion cells on the soil side. This galvanic corrosion cell formation is more pronounced if the tank content is stored at elevated temperature and/or located in aggressive soil.

Product Number: 51323-19186-SG
Author: Benjamin Chaloner-Gill, Amal Al-Borno, Martin Quintero, Moavin Islam, Brock Genter, Yuan Li
Publication Date: 2023
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This paper details the findings of a comprehensive study conducted to determine if a spray applied two- component inorganic industrial coating can be used to mitigate the soil-side corrosion of aboveground carbon steel storage tank bottoms. The coating is applied on the soil-side which is on the back side of the welded sections of the tank bottom. The study included microstructural characterization of the weld zone and surrounding areas of welded steel test panels. which were coated on the back side. The coating material as well as the passive layer formed by the coating on the steel surface were analyzed using XRD, SEM and EDS for their morphological and structural characterization before and after welding. Surface characteristics of the passive layer formed on the coated carbon steel samples were investigated with the help of electrochemical techniques consisting of Ecorr, LPR and CPP studies. Performance tests on coated panels were conducted under simulated field environments using Cyclic Aging Resistance and Immersion tests.


The electrochemical data indicated that the high heat input during the welding process affects the nature and quality of the passive layer on the carbon steel surface which implies that the steel surface in the weld and heat affected zone (HAZ) areas may be less corrosion resistant compared to the steel surface in non-welded areas. However, the coating showed resistance1 to seawater immersion and cyclic aging tests demonstrating its effectiveness in the protection of tank bottom plates from corrosion induced by underground water and soil when applied on the backside of welded steel plates, as claimed by the manufacturers.

This paper details the findings of a comprehensive study conducted to determine if a spray applied two- component inorganic industrial coating can be used to mitigate the soil-side corrosion of aboveground carbon steel storage tank bottoms. The coating is applied on the soil-side which is on the back side of the welded sections of the tank bottom. The study included microstructural characterization of the weld zone and surrounding areas of welded steel test panels. which were coated on the back side. The coating material as well as the passive layer formed by the coating on the steel surface were analyzed using XRD, SEM and EDS for their morphological and structural characterization before and after welding. Surface characteristics of the passive layer formed on the coated carbon steel samples were investigated with the help of electrochemical techniques consisting of Ecorr, LPR and CPP studies. Performance tests on coated panels were conducted under simulated field environments using Cyclic Aging Resistance and Immersion tests.


The electrochemical data indicated that the high heat input during the welding process affects the nature and quality of the passive layer on the carbon steel surface which implies that the steel surface in the weld and heat affected zone (HAZ) areas may be less corrosion resistant compared to the steel surface in non-welded areas. However, the coating showed resistance1 to seawater immersion and cyclic aging tests demonstrating its effectiveness in the protection of tank bottom plates from corrosion induced by underground water and soil when applied on the backside of welded steel plates, as claimed by the manufacturers.

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