2019 Refinery Explosion Final Report Issued


The U.S. Chemical Safety and Hazard Investigation Board released its final report earlier this month for the 2019 Philadelphia Energy Solutions Refinery explosion in Philadelphia. According to the investigation, a corroded pipe elbow ruptured resulting in the explosions and fire.

During the incident, the CSB reports that over 5,000 pounds of highly toxic hydrofluoric acid were released, a 38,000-pound vessel fragment was launched offsite and an estimated $750 million in property damage loss resulted.

What Happened

Around 4 a.m. on June 21, 2019, an explosion occurred at the PES refinery, followed by two additional explosions, ultimately ensuing a massive fire. According to The Philadelphia Inquirer, the fireball that resulted from the explosions was captured by a weather satellite in space due to the incident's intense heat.

Located within what was previously a Gulf Oil Corp. refinery was the impacted unit, which produces alkylate (a booster used for gasoline octane). PES is a 150-year-old company combination of the Gulf and Atlantic Reining Co. campuses. Although the complex has two alkylation units, the affected unit uses a deadly chemical, hydrogen fluoride, as a catalyst.

Officials had since gone on record to say that none of the chemicals were released in the explosion.

According to Philadelphia Deputy Fire Commissioner Craig Murphy, the general vat area­—where the fire had been burning—contained propane and butane, which was being fed by a main source. With PES unable to gain access to the proper valve to shut off the continuously burning gases, PES firefighting teams and the Philadelphia Fire Department decided to confine and contain the blaze.

“It is safer if it burns itself out,” Murphy said at the time, adding that, “whatever's blowing out of the main blows right into the atmosphere.”

Fire Commissioner Adam Thiel also noted that it “is standard practice when fighting a fire of this type to let the flammable gases burn away in a controlled fashion.”

Over the course the next two days, until PES teams could successfully shut off the main, crews continued to pour water on nearby pipes and tanks to keep them cool. Officials reported the following Sunday that the fire had been effectively extinguished by Saturday afternoon.

As a result of the incident, five refinery workers suffered minor injuries and were treated at the scene. Neighboring residents were also advised to shelter in place until officials reported that tests for 61 chemicals determined safe air quality, which took place only a few hours after the blasts.

Philadelphia Fire Department spokesperson Kathy Matheson added that this was the second fire to occur at the plant that month. However, the June 10 fire appeared to be smaller and was “quickly contained and safely extinguished.” CNN also reported that the two fires were unrelated in nature and cause, according to Philadelphia Mayor Jim Kenney.

The fire department’s hazmat unit and public health department continued to monitor the air quality every two to three hours. Investigations were also launched by the Occupational Safety and Health Administration; the Bureau of Alcohol, Tobacco, Firearms and Explosives; the U.S. Chemical Safety and Hazard Investigation Board; and the fire marshal's office.

The day of the incident, future gasoline prices saw a 3.9% increase—the largest spike in three months—due to the concerns about the explosion’s impact on summer supplies. AAA Mid-Atlantic stated that the Monday prices had not yet been reflected at the pump, but that could possibly have changed “depending on how long the refinery is shut down, as well as other factors.”

However, although PES claimed to be the largest oil refinery on the East Coast, employing more than 1,000 workers and processing about 335,000 barrels of crude oil per day, a report by the Philadelphia Inquirer suggested that incident may have pushed them to the brink financially.

Having just emerged from bankruptcy in 2018, the six months leading up to the incident had shown a decline in the refinery’s cash balance, as well as a 7.5% increase in long-term debt during the first quarter of this year, totaling $755 million. Additionally, the owner’s stake value decreased by 43% in the first quarter to $82 million.

Industry experts estimated that the cost of replacing the damaged equipment from the fire could easily top $100 million, a skeptical option, commented energy analyst Christine E. Simeone, regarding her report for the University of Pennsylvania’s Kleinman Center for Energy Policy. The report was published in fall 2018 and suggested that PES is so uncompetitive and debt-burdened that it’s “likely” to file for bankruptcy (again) by 2022.

Already that year, the company had deferred matching retirement payments until 2020, froze employee bonuses and reorganized its management team.

Just days after the explosion, the plant announced it would halt operations. The following month, the company filed for bankruptcy.

In October 2019, the CSB initially reported that a pipe elbow had corroded to roughly half the “thickness of a credit card.” The piece ruptured in the refinery’s alkylation unit, which resulted in the release of process fluid that included over 5,000 pounds of hydrofluoric acid.

The update also details that the elbow was susceptible to corrosion due to the hydrofluoric acid in the process fluid, and though the pipe thickness was measured periodically, the elbow at issue had not been assessed for corrosion. That segment of piping also had high nickel and copper content.

The Board wrote: “Various industry publications have found that carbon steel with a higher percentage of nickel and copper corrodes at a faster rate than carbon steel with a lower percentage when used in a process with hydrofluoric acid.”

A following event, which involved the rupturing of a V-1 Treater Feed Surge Drum, launched a 38,000-pound vessel fragment across the Schuylkill River. Two other fragments landed in the refinery.

Final Report, Redevelopment Plans

The final investigative report, released on Oct. 11, identified several safety issues that contributed to the incident, including mechanical integrity and verifying the safety of equipment after changes to good practice guidance.

The CSB reportedly determined that the pipe elbow that failed had corroded faster than other piping in the HF alkylation unit because the steel pipe elbow contained a higher content of nickel and copper than other piping in the unit.

Additionally, when the pipe elbow was installed in 1973, the standard set by the American Society for Testing and Materials (ASTM) for carbon steel piping did not specify limits on nickel or copper content. However, that standard changed by 1995 and was revised enough that the pipe elbow no longer met these requirements due to high levels.

CSB Interim Executive Authority Steve Owens said, “This is one of the largest refinery disasters worldwide in decades in terms of cost.  the local community in Philadelphia fortunately was not seriously harmed, but given the refinery’s location, it could have been much worse. This incident should be a wake-up call to industry to prevent a similar event from occurring in the future.”

 “A comprehensive evaluation of unit piping never occurred despite regulations from both the Occupational Safety and Health Administration (OSHA) and the Environmental Protection Agency (EPA) requiring companies to determine that their equipment is safe to operate after industry standards are updated. To prevent catastrophic incidents companies and industry trade groups must ensure process safety when new knowledge on hazards is published,” said CSB Supervisory Investigator Lauren Grim.

The CSB found that there were no remotely operated emergency isolation valves installed in the HF alkylation unit to isolate nearby hydrocarbon sources that could then flow through the failed elbow. While these are not explicitly required by the current American Petroleum Institute standard, such valves could have prevented subsequent explosions.

Because of this, the Board is recommending API to update its standard on Safe Operation of Hydrofluoric Acid Alkylation Units to require installation of remotely operated emergency isolation valves on the inlets and outlets of all hydrofluoric acid containing vessels, and any hydrocarbon containing vessels meeting defined threshold quantities.

Additionally, the investigation found that pumps design to spray large volumes of water to suppress an HF release failed to activate early in the incident, as remote operation controls to the pumps were damaged by the fire and explosions. By the time the release began, highly toxic materials escaped the equipment and vaporized in the air.

As a result, the CSB is recommending to API to update the same standard to require that critical safeguards and associated control system components be protected from fire and explosion hazards, including radiant heat and flying projectiles.

Overall, the CSB recommends an “inherently safer design” approach to replacing highly toxic chemicals, such as hydrofluoric acid. The investigation also found that there is no federal regulatory requirement for refineries to analyze inherently safer design strategies to reduce the risk of serious accidental releases. 

According to its final report, the CSB is recommending that the U.S. Environmental Protection Agency:

  • Require petroleum refineries to conduct a safer technology and alternatives analysis (STAA) as part of their Process Hazard Analysis under EPA’s RMP rule, and evaluate the practicability of any inherently safer technology; and
  • Initiate prioritization under the Toxic Substances Control Act (TSCA) to evaluate whether hydrofluoric acid is a high priority substance for risk evaluation, and if it is, conduct a TSCA risk evaluation of HF and implement any identified risk mitigation requirements.

The full report can be read here.

Following its declaration of bankruptcy, PES put up the 1,300-acre site for sale, which was purchased by Hilco Redevelopment Partners for $225 million with plans for redevelop the site into logistics facilities and research labs. This will involve safety dismantling over 100 buildings, 3,000 tanks and 950 miles of dirty pipeline.

Dubbed the “Bellwether District,” the company describes its plan as a “new home for e-commerce, life sciences, and logistics leaders.” The first tenants are expected to move into the site in 2023, according to reports.

One of the biggest issues the company faces is removing piping or tanks in which petroleum products were left, hardening and becoming extremely hard to remove. The site also reportedly has 30,000 tons of asbestos that must be stripped off of the pipes.

Hilco estimates that the site will reportedly generate $41 million a year in tax revenue for the city each year and employ over 14,000 workers.


Tagged categories: Accidents; Corrosion; Explosions; Fire; Hazardous air pollutants; hazardous materials; Health & Safety; Health and safety; NA; North America; Oil and Gas; Pipes; Program/Project Management; Quality Control; U.S. Chemical Safety Board

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