Case Study: RBI for Atmospheric Storage Tanks – How One Client Achieved $7MM in Inspection Savings

Learn how we helped a facility update its tank inspections through an RBI assessment to reduce the number of non-compliant tanks and save the facility $7MM in budgeted tank inspections.

The Challenge

A refinery located along the Texas Gulf Coast produces up to 325,000 barrels per day of environmentally clean fuels and products. Due to the complexity of this facility, site management was very proactive in establishing a Risk-Based Inspection (RBI) program for its fixed equipment and piping, however it needed a way to ensure compliance requirements were met for its tanks, many of which were overdue for internal inspections.

While tank inspections represent a large cost for facilities, they also present logistical challenges for operators who coordinate hundreds of tanks across thousands of miles. Managing these inspections often requires more strategic planning than those vessels seen in a large, concentrated facility with a full-time inspection department.

Even in large facilities like the Texas refinery, the extensive nature of tank inspections often results in grave deficiencies in the area of data management. Instead of leveraging the data to predict failures, large stacks of documentation are often abandoned in tank inspection cabinets or misplaced, resulting in severe data gaps. In terms of Risk-Based Inspection, tanks require a different approach than pressure vessels and piping. These differences, include:

Consequence of Failure:

• Small leaks may go undetected for months
• Leaks are governed by liquid level as opposed to pressure
• Environmental effects are generally mitigated due to liquid state fluids and containment dikes
• Leak detection and secondary containment systems can alter the consequence of failure
• Tank areas are generally much less populated than process areas
• Roof, shell, and floor failure all result in different impacts

Probability of Failure:

• Tank failure may not occur until zero wall, as pressure is solely governed by liquid level
• Multiple tank shells exist that often possess different corrosion allowance values
• Properly assessing corrosion rates on the floor requires more advanced inspection or modeling
• The roof, shell, and floor all pose different damage types and susceptibilities

Pinnacle’s Solution

Pinnacle’s team was originally hired by the facility to implement a Risk-Based Inspection program for its fixed equipment and piping. After seeing positive results from this process, site management moved forward on utilizing Pinnacle to conduct an RBI assessment for their 226 tanks. The results from the completed RBI implementation project were as follows:

• RBI plans accelerated the inspection due dates for 33 tanks, deferred the dates of 182 tanks, and left 11 tanks unchanged.
• The facility had been struggling to bring its tank inspection up-to-date as they had 46 tanks out of compliance per API 653 prior to the assessment. After conducting an RBI assessment, the number of non-compliant tanks was reduced to 26, therefore saving the facility $7 million in budgeted tank inspections in just the first year.
• After conducting an extensive assessment to understand the status of the tanks, Pinnacle’s team identified 27 high consequence tanks, two of which were flagged as being out of compliance.

Results

Through the course of several hundreds of tank RBI assessments, Pinnacle’s team of experts has demonstrated a substantial return on investment. While some tanks do in fact assume more aggressive inspection plans from the assessment, on the whole, the cost benefits have been outstanding. Overall, the benefits can be summarized by the following:

• Inspection Savings: An extension of low risk internal inspection due dates resulted in an average of 1,500 percent return on investment or an average of $40,000 savings per tank.
• Reduced Tank Downtime: Risk-Based Inspection intervals now average 24 years between internal inspections.
• Improved Compliance: While this remains particular to the project, many tanks deemed out of compliance by API 653 were deemed suitable for continued service and pushed beyond the assessment date.
• Aside from the hard cost savings, the refinery was also left with a comprehensive and controlled electronic library of all tank documentation and a validated tank database with tank design, operating, process, and inspection data. Armed with these tools, the facility is able to confidently and efficiently manage their tanks into the future.