Maintenance Strategies for Aboveground Storage Tanks in Crude Oil Service — Part 2

Introduction

In today’s market, the price of West Texas Intermediate (WTI) crude oil continues to fluctuate. From June 2014 to June 2015, crude oil prices dropped by 43.3%. There are many contributing factors to declining oil prices and the decrease in worldwide demand, and these low prices significantly affect countries where the main source of revenue is the oil and gas sector. The potential impact of falling crude oil prices elevates demands for return on investments on new projects, aged infrastructure, refining and exploration costs, operations and maintenance costs. Without a properly maintained energy infrastructure for both transportation and storage, many oil production opportunities would have to be abandoned. Aboveground Storage Tanks (AST) are essential to any successful oil and gas operation and must be properly managed to ensure operations function in a safe and reliable manner. In this current economic climate, an operator could suffer crippling losses if one of their large ASTs experienced a catastrophic failure. The costs associated with spill clean-up, recovering any crude oil or chemicals, repairs or replacement of equipment, remediating any damage to the environment, public relations, and restoring the company’s reputation would do serious damage to the operator’s financial status.

ASTs are large stationary assets designed to temporarily hold liquid or gas substances for a period of time before being transported to processing facilities or retailers. When it comes to thorough maintenance and inspection practices, ASTs are often neglected, especially when tight margins push operators to focus the budget towards operating their facility and deferring maintenance costs. This can negatively impact the operations and reliability of ASTs and can potentially result in catastrophic failures with serious consequences.

The design life of an AST ranges between 25 and 30 years. ASTs can be easily overlooked in large oil and gas companies as they do not create daily operational issues. As a result, asset owners often tend to put ASTs on the low priority list, which can lead to poor maintenance practices. A high risk associated with operating a poorly maintained AST is that leaks can occur and contaminate soil and drinking water supplies and pollute the surrounding environment. One pint of crude oil released into the water supply can spread over a surface area of one acre, which can seriously impact marine life, the fishing industry, and nearby people. An even greater risk is operating ASTs in close proximity to densely populated areas where failures such as tank explosions and fires can affect nearby communities and environment. Poor maintenance practices are not forgiving; an organization that takes years to build its reputation can lose it in only a few seconds. Thus, it is important that systems are in place to ensure the integrity of ASTs. Today, many organizations are implementing new inspection techniques, asset integrity management strategies, and safety management systems to eliminate crude oil AST failures.

In Part 1 of this 2-part series, published in the July/August 2015 issue of Inspectioneering Journal, I discussed corrosion control methods and some effective techniques for inspecting ASTs, and also identified several root causes of AST failures in crude oil service. In this second installment, I will briefly review the costs associated with AST failures and discuss maintenance strategies to help prevent and/or mitigate predictable and unforeseen incidents.