The Environmental Protection Agency (EPA) requires 80 percent of the highway diesel fuel produced or imported to be ultra low sulfur diesel (ULSD) fuel to replace most low sulfur diesel (LSD) fuel. That mandate went into effect June 1, 2006, and since late 2007, there has been an uptick in reports of corrosion in underground storage tank and dispensing systems containing ULSD.
ULSD is described as a cleaner-burning diesel, according to the Clean Diesel Fuel Alliance (CDFA), and contains a maximum 15 parts-per-million (ppm) sulfur. By the end of this year, all highway diesel fuel sold must be ULSD fuel. However, since the first complaint was posted on a Petroleum Equipment Institute (PEI) Internet forum in December 2007, the corrosion reports have not gone away.
“There are filters plugging,” said Bob Renkes, executive vice president and general counsel of PEI, “column pipes wearing,” among other problems being reported to PEI. Renkes said since PEI first became aware of the issues, the association felt it was critical to take the lead in investigating the corrosion problems.
PEI called a meeting earlier this year at EPA’s Office of Underground Storage Tanks to discuss the reports with oil marketers, additive manufacturers and other petroleum industry organizations. The group agreed to develop a survey to gauge how substantial the issues were and if so, to investigate the problem further and come up with a solution.
PEI has just concluded the survey, which included almost 1,200 respondents. Nearly 42 percent said they were receiving more reports now than before ULSD was introduced of problems related to ULSD, such as premature failures, accelerated corrosion, rust, gasket or seal problems, and/or equipment operational problems, according to the PEI Tulsa letter sent April 12.
The PEI survey results were announced shortly after it ended Tuesday, April 6, and representatives of various trade associations and government agencies agreed that the potential causes of these issues is unclear. “The Clean Diesel Fuel Alliance will develop guidance on monitoring and maintaining fuel distribution and dispensing equipment,” said Tisha Petteway with the EPA. “They will also explore the best ways to gather additional information to get a better understanding of the nature of the issue.”
One of the associations involved is the Steel Tank Institute, and director of technical services, Lorri Grainawi has been fielding the ULSD complaints to come into STI in the last couple of years. She said there really isn’t any clear pattern to the reports of excessive corrosion of metal equipment and components.
“It’s happening in various regions, so we can’t really say it’s a particular refiner or anything like that,” Grainawi said.
The PEI survey shows the elusive nature of this as well, with reports of nearly 5,000 locations with problems. The locations were widespread and not specific to any one area of North America. Among the complaints made by the survey respondents, the following situations were most commonly reported: filters clogging/requiring more frequent replacement; seal/gasket/O-ring deterioration; STP replacement/column pipe wear/motor problems; tanks rusting/leaking (includes tanks on vehicles); meter failure; line leak detectors damaged or broken; automatic nozzle shutoff failure/shorter lifespan; tank probes malfunctioning; check valves not seating; shear valves not sealing/failing tests; swivels failing/shorter lifespan; dispenser leaks/failure/premature replacement; solenoid valves clogged/failing; corrosion on the riser pipe; and pipe failure.
There are a number of theories as to what is causing this. “There are so many theories, which is the problem,” Grainawi said. “Depending on who you talk to, it could be fuel reacting with an additive,” or it could be a maintenance issue. She said some have described it as the perfect storm as a combination of factors and “when those combination of factors happen, the corrosion happens.”
As of right now, there is no known solution to help stop or prevent the problem, not even a specific additive. “In fact, too much additives can create problems,” Grainawi said. But she does recommend keeping tanks as clean as possible so there is nothing for the fuel to react with.
Clearly, once a better understanding of the corrosion problems is reached, more preventative suggestions will follow. “My number one question is if it’s happening at one gas station and not at the gas station across the street and they’re both getting their fuel at the same place—why is it happening here and not there?” said Grainawi.
If marketers do experience a problem with storage or dispensing equipment of ULSD, Grainawi advised them to report it to their local association and to let the vender of the fuel know as well.