In liquid processing industries, the value of tanks is often taken for granted. In reality, industries that utilise tanks could not operate without the storage of their unrefined and refined products. Managing major repairs in order to optimise cost, reduce risk, and minimise downtime is a challenge for all tank owners. A leaking bottom could mean thousands of gallons of a hazardous or explosive material is spilled onto the ground or into a waterway, affecting drinking water, agriculture, wildlife, and outdoor recreation. Tank integrity is necessary for the community, the environment, and the economy. Therefore, it is no surprise when a customer is cautious about the need for a tank bottom replacement. Each tank owner’s goal is to choose the right repair option that will optimise the lifecycle cost, minimise downtime, and ensure that the integrity of the tank is maintained for the length of the inspection interval.
A customer consulted with Tanco regarding a tank with severe bottom corrosion, both top and under side. After careful evaluation, the only viable repair option was to install a new bottom. The tank had an external floating roof and was 150 ft in dia. x 48 ft tall. The tank foundation consisted of a concrete ring wall, a release prevention barrier, a sand pad, cathodic protection, and leak detection. The tank was critical to the customer and the cost of an outage was significant. However, the customer sought to maximise the lifecycle cost while its asset was out of service. The company was a responsible care provider with a commitment to environmental stewardship, which meant that prevention of a release in the future was one of its top priorities. Tanco's task was to provide the customer with multiple repair methods, along with advantages and disadvantages of each option.
Written by Brandy Gibbons, Craig Greenslit, Brent Porter, Joshua Flock and Keegan Maloney, Tanco Engineering Inc., USA.
Read the article online at: https://www.hydrocarbonengineering.com/special-reports/03012018/start-from-the-bottom/