Abstract

Lining the floor bottoms and vapor space within an Aboveground Storage Tanks (AST) is a well-proven method to mitigate internal corrosion of the carbon steel substrate. An AST is usually scheduled for out-of-service inspection at least 10 years after its initial in-service date; sometimes the out-of-service schedule could be even longer (e.g., over 20 years) depending on the local regulations and engineering assessments. Therefore, the selection of an appropriate tank lining system and its application are critical for long term performance in maintaining the integrity of the assets.

API Recommended Practice (RP) 652 [1] provides recommendations on the application process of lining materials and a guideline for lining system selection. The same practice lists the general benefits and limitations of thin and thick film linings and provides items that should be considered when selecting a liner; however, API RP 652 does not provide a testing protocol for lining selection and qualification.

This paper presents a qualification test protocol for selecting lining for storage tank bottoms and vapor spaces exposed to hydrocarbon products. The protocol includes, but is not limited to, standard atlas cell, pressurized atlas cell, and autoclave testing. In addition, the paper discusses best practices for application of these systems on large diameter (> 50 m) tanks in crude oil service based on extensive field experiences.

Introduction

Internal corrosion within an aboveground storage tank (AST) or breakout tank may be attributed to water within the crude oil to contact the carbon steel surface. Hydrocarbon products will contain small fractions of basic sediment and water (BS&W) content within crude oil transmission pipeline. The BS&W of hydrocarbon products from Canada are restricted by tariffs to typically not exceed 0.5 percent by volume, while most U.S. tariffs restrict the content to less than 1.0 percent [2]. This water is primarily present as a stable emulsion, maintaining an oil-wet pipe, protecting the internal surface of the pipeline from corrosion [3].

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