Highlighter-Spring-2015

Brian Lunsford, Senior Project Manager, was featured in Tank Storage Magazine’s March/April issue for his article on internal storage tank inspections. This is the second article Brian has contributed to the industry publication in the last year. In this article, Brian discusses the appropriate time line for terminal operators to perform tank inspections, as well as ways to prolong tank integrity. He also provides specific case studies that highlight both his own as well as Pond’s expertise in the ICM field. To read the entire article please visit http://www.tankstoragemag.com/content_ item_details.php?item_id=878#. n ICM Group Proves It ’s An Industry Thought Leader 86 March/April 2015 • TANK STORAGE tank inspection API 653 provides storage tank owners and operators with maximum inspection intervals to establish initial and ongoing tank integrity. To this end, designed and provided to prolong tank integrity with a reasonable amount of risk. Based on those safeguards, an owner/operator has the option to delay the initial inspection for as many as 30 years. But, there are instances where the precautions may not be enough to ensure integrity, allowing issues to develop beneath the surface, and go undetected for decades. Is waiting for that maximum interval always the best course of action? Two case studies may suggest otherwise. barrel aboveground tank petroleum product is located at a coastal tank farm. The tank was built in 2006 in accordance with API 650, 10th edition. In addition, the tank was built on a concrete ring wall foundation and possessed an under-tank liner for containment with a sand bedding and galvanic cathodic protection (CP) system. Upon completion of tank erection, the tank was commissioned and placed into service. The owner of the tank implemented an aggressive programme requiring inspections at a maximum 10 year interval, regardless of age. The initial API 653 out-of-service tank inspection was performed in 2014, approximately eight years after tank erection. A to identify topside and soil- side corrosion and pitting. As a result of this inspection, multiple soil-side indications were found. Due to the number of indications, the and scanned with ultrasonic thickness testing (UTT) to quantify remaining plate thickness. The results were staggering -- while the original inches, widespread corrosion degradation was found with numerous remaining thicknesses measuring less than 0.100 inches. Corrosion rates as high as 15 mils per year (MPY) were discovered, affecting approximately 75% of the tank bottom. The owner of the tank provided extensive construction records and test reports to an engineering team to determine the cause of the accelerated corrosion. The owner had other tanks constructed in the same manner, and was understandably concerned about them. Still, from the owner’s perspective, all necessary precautions had been taken: he had contracted with a professional would result in a quality product. He had secured on- site supervision throughout the construction process. Material submittals required approval by the construction manager prior to installation. Such careful safeguards should have resulted in a sound tank – so what had occurred? A review of the records revealed that in the design plans, the sand bedding was quality material with low chlorides, low moisture, low Material records indicated that the sand met all of these qualities; however, the material submittal was dated 12 months prior to the arrival of the material on-site. It followed, then, that the batch sampled for the material submittal was not the same batch that was actually provided. Moreover, photos taken during construction showed that, once on-site, the sand was placed in a pile near the tank for several months. In the high humidity coastal environment where the tank was located, the sand became wet and contaminated over the period of time it was exposed. The engineer did not CP systems. As a result, he provided a cookie-cutter CP system design which was not suited for the environment. To this end, the engineering documents indicated that the CP system was designed as a galvanic anode system; these type of systems, however, have very limited applications in aboveground storage tanks, as they supply low amounts of protective In a perfect environment of dry, high resistivity, chemically neutral sand, they can provide corrosion protection; in an aggressive environment, by contrast, standards point to the use of the more robust impressed current type of system. Further, while the owner contracted with a ‘corrosion expert’ to perform annual inspections of the CP system, examination of those surveys, along with the initial survey, revealed that the system never met the NACE International established criteria for effective CP. In other words, the CP system was not providing adequate corrosion protection. And, while the owner reasonably thought he had taken the necessary safeguards to protect his investment, in Initial storage tank internal inspections Terminal operators should include a baseline inspection assessment within 5-10 years of tank construction Chrissy Colquitt – Marketing Coordinator Terminal operators should include a baseline inspection assessment within 5-10 years of tank construction. “ “