Materials Performance Supplements

Corrosion Prevention and Control for Tanks 2017

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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5 TANK CORROSION CONTROL SUPPLEMENT TO MP MATERIALS PERFORMANCE MAY 2017 the United States that are affected by corro- sion, it is alerting all owners of those USTs about the risks and advising them to check their systems for corrosion and take steps to ensure proper operability. "EPA's notification recommends owners check inside their tank systems and further investigate the condition of their diesel fuel tanks," the EPA writes. "Owners' awareness and early actions could help protect them from higher repair costs and help protect the environment from contamination from releases." The EPA contends that the results of this research suggest that USTs storing diesel are susceptible to developing rapid and severe corrosion, adding that this increased corro- sion could increase the potential of an unin- tended tank release due to a failure within release pre vention equipm ent, release detection equipment, or the UST itself. The agency notes that aboveground storage tanks (ASTs) storing diesel are out- side of its regulatory purview, but cautions that its research shows both USTs and ASTs being at risk of corrosion. In addition, small, non-federally regulated USTs storing diesel fuels both aboveground and belowground are also likely to be at risk of corrosion.To address these concerns in the future, the EPA explains that multiple approaches may be necessary. "Initially, awareness that the problem exists is imperative for owners, industry, and state and federal agencies so that own- ers know they should inspect their UST sys- tems," the agency says. " Via our state and industry partners, EPA will notify UST own- ers about the findings." Beyond general awareness, the agency says enhanced system maintenance and rou- tine inspections are immediate steps that owners of USTs storing diesel should take. In particular, vigilant aqueous phase monitor- ing is a critical maintenance program. "In our research, the presence of water appears possibly correlated, albeit not sta- tistically significantly, with an increased prevalence of corrosion," the agency says. "Industry documents suggest the removal of any water when found, possibly more often than owners have traditionally done in the past, should be considered to limit the potential for microbial growth in USTs storing diesel. Owners should understand where water collects in their particular systems due to tank tilt and ensure water sensor equipment is monitoring at the most appropriate place." The agency also advises tank owners to consult industry documents as sources of helpful information about limiting poten- tial corrosion impacts. In its report, the EPA praises industry for its willingness to tackle the problem. "Industr y is continually working to improve equipment and ensure functional- ity with various fuels on the market, includ- ing designing and offering equipment in corrosion-resistant versions like stainless steel," the report says. Looking ah ead , th e report explains that knowing the condition of equipment through routine inspections is critical to identifying the development of corrosion over time. These assessments could include looking at filters and filter housings for signs of debris or deterioration, as well as removing the drop tube and ATG probes to assess whether automatic shutoff overfill devices and monitoring floats are properly functioning. In-tank video inspections, if available to the owner, could also serve as a proac- tive and useful way to visualize and docu- ment conditions inside the tank—because visual observations from the surface may not always show the true extent of corro- sion inside the tank. "Addressing corrosion issues at early stages could reduce repair and replacement costs later, as well as reduce the risk of extremely expensive environmental release clean-up costs," the EPA says. In closing, the agency notes several approaches that could be helpful in pre- venting tank corrosion: • Regularly monitoring and removing any water present in the UST • Filtering fuel for water and particu- lates before they are delivered into the UST, or recirculating and filter- ing water and particulates while they are stored • Adding nitrogen-generating equip- ment to limit an oxygen-rich atmo- sphere inside the tank • Using liquid corrosion inhibitor additives or other corrosion inhib- itors, including filming amines • Using biocides or other fuel treat- ments to kill or disrupt existing microbial colonies, or to prevent future MIC The EPA believes technologies enabling each approach are either available now or are currently in market development. Going for ward, the agency says its research is ongoing in an attempt to pinpoint the pre- cise causes of corrosion in USTs storing die- sel and to identify a solution. But until those causes and solutions are identified, the EPA sees education and outreach, additional investigations, preventive maintenance, the further adoption of corrosion-mitigating products in the market, and potential mod- ifications to industry fuel distribution and storage practices as crucial interim steps. "These may help reduce corrosion and the risk of potential releases of fuel to the environment from USTs and other tanks storing diesel fuel," the EPA concludes. Source: U.S. EPA, Reference 1 "Investigation of Corrosion-Inf luencing Fac- tors in Underground Storage Tanks with Die- sel Service," U.S. Environmental Protection Agency Office of Underground Storage Tanks, EPA 510-R-16-001, July 2016. New EPA Study Addresses Diesel Tank Corrosion Corrosion found in the EPA's study was geographically widespread and affected systems with multiple varieties of tanks, including steel.

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