Materials Performance Supplements

TANK 2018

Materials Performance is the world's most widely circulated magazine dedicated to corrosion prevention and control. MP provides information about the latest corrosion control technologies and practical applications for every industry and environment.

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4 MAY 2018 W W W.MATERIALSPERFORMANCE.COM TANK CORROSION CONTROL SUPPLEMENT TO MP Tank Protection Articles Materials Selection for a Bulk Chemical Handling Facility—A Case Study The joint operation bulk chemical han- dling facility at Wafra Oil Field, located in the Partitioned Neutral Zone area between the Kingdom of Saudi Arabia and the State of Kuwait, was experiencing frequent leaks during storage and transfer of integrity prod- ucts. The bulk chemical facility 's tanks, pumps, and connected piping were con- structed with internally coated carbon steel (CS) components to meet cost reduction requirements. An engineering assessment determined that incompatibilities between chemicals used as well as long-term corrosion resistance of tanks and piping should have played a more important role in material selection prior to the facility's construction. According to a review 1 of the corrosion issues encountered at the facility, authored by NACE International members Tariq Kam- shad, Manickavasagan Sabesan, Siriki Ravi Shankar, and their colleague A/Rahman Al-Ghamdi from Joint Operations-Wafra New tanks and associated piping at the Wafra Oilfield's bulk chemical handling facility were constructed with Type 316 and Type 316L SS. (Saudi Arabia Chevron—Kuwait Gulf Oil Co.), the bulk chemical facility was con- structed in 2001 to provide bulk storage of integrity and production chemicals to con- trol corrosion and emulsion issues in the oil field's production wells, process facility, and water handling unit. The bulk facility consisted of eight tanks, transfer piping, a centrifugal pump, and instrumentation items. The storage tanks were constructed of ASTM SA 283 Grade C CS and the piping was constructed of ASTM SA 106 Grade B CS. The tanks, inlet and outlet piping, and drain lines were lined with a phenolic epoxy or fiberglass coating since prolonged stor- age in bare CS may cause the properties of the stored products to change. The integrity chemicals used for corro- sion control of the oil field's water process are a water-based corrosion inhibitor, bio- cide, and scale inhibitor, and each has a low pH—in the of range of 2.5 to 5.5. A common manifold is used to transfer these water- based chemicals. Generally, the corrosion inhibitor should be compatible with other c h e m i c a l s b e c a u s e i n c o m p a t i b i l i t i e s between chemicals are intensified if they are mixed in the same transfer line. To avoid this, a water-washing cleaning process was developed; however, the CS piping is not always properly drained or cleaned after each use. As a result, neat chemical residu- als accumulate in low spots, which cannot be avoided. The engineering evaluation determined that improper selection of materials and components caused corrosion of the struc- tures, which led to poor containment reli- ability, increased maintenance activities, and additional safety and environmental concerns due to chemical spills. The accu- mulation and increased concentration of the neat chemicals in the manifold led to integrity chemical leaks, which caused a dramatic increase in the volume of pipeline maintenance and replacement work. Also, the linings in the CS delivery piping and storage tanks were found to have peeled and blistered. Since the pH of the integrity chemicals is relatively low, the authors note in the review that materials such as CS should not have been used for the bulk storage f a c i l i ty. C h e m i c a l s w i t h l o w p H c a n increase corrosion risks, promote internal pitting, and escalate elastomer degrada- tion. They comment that CS piping was found to be experiencing severe corrosion with localized holes. Field experience indi- cated that most of the piping leaks were due to integrity chemicals in contact with the piping, and over 80% of all piping leaks since 2001 are attributed to accelerated corrosion attack. Lining CS tanks and pip- ing for bulk storage of chemicals is not rec- ommended, because any single holiday in the coating could cause product contami-

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