United States of America

On March 23, 2005, a catastrophic explosion occurred at BP’s Texas City refinery in Texas, USA. The incident transpired during the startup of a hydrocarbon isomerisation (ISOM) unit. Operators inadvertently overfilled a raffinate splitter tower, causing it to flood with hydrocarbons. This led to the over-pressurisation of the tower and the release of a highly flammable hydrocarbon vapor cloud. The vapor ignited, resulting in a massive explosion that caused extensive damage across the refinery.

Date
23/03/2005
Location
United States of America
Industry
Energy (Oil Refining)
Substance
Hydrocarbons
Cause

The immediate cause was the overfilling of the raffinate splitter tower during startup, which led to the discharge of flammable liquid from the blowdown stack and its subsequent ignition.

Underlying causes were numerous and included:

  • Failure to establish effective safe operating limits.
  • Deficiencies in equipment design, including inadequate level indication, lack of automatic safety controls, and a blowdown system that discharged directly to the atmosphere without a flare. Previous tower overfilling incidents were not adequately addressed.
  • Inadequate startup procedures, including not removing liquid from the tower.
  • Inadequate shift turnover, leading to a loss of situational awareness.
  • Mechanical integrity deficiencies, including failures of critical instrumentation like the level transmitter (LT-5100) and a corroded high-level alarm float (LSH-5020).
  • Company safety culture, which lacked a focus on process safety management (PSM), encouraged cost-cutting over safety investments, and did not effectively respond to reports of serious safety problems.
  • Ineffective incident investigation system that failed to learn from previous blowdown incidents.
  • Poor placement of occupied trailers too close to the hazardous ISOM unit.
  • Insufficient operator training and the lack of supplementary assistance during the hazardous startup.
Consequence

The incident resulted in a major explosion and fire at the refinery. This led to:

  • 15 fatalities.
  • 180 injuries.
  • Significant financial losses exceeding $1.5 billion.
  • Alarm to the community.
  • Severe damage to the ISOM unit, surrounding parking areas, the satellite control room, and the catalyst warehouse.
  • Damage to over 40 trailers, with 13 destroyed.
  • Damage to approximately 70 vehicles.
  • Blast damage to buildings in surrounding units and off-site buildings.
  • Post-explosion fires.
  • Community shelter-in-place orders were issued in subsequent incidents at the refinery.
Injuries

180

Fatalities

15
All fatalities occurred in or near trailers located close to the ISOM unit.

Lessons Learned
  • Process unit startup is a significantly more hazardous period than normal operations and requires supplementary assistance and rigorous procedures. Incidents are significantly more likely during startups.
  • Blowdown systems discharging flammable materials directly to the atmosphere without a flare are inherently unsafe. Previous releases from the ISOM blowdown stack were early warnings that were not heeded.
  • Siting occupied trailers close to process units handling highly hazardous materials is extremely dangerous. Temporary structures are more susceptible to damage from explosions.
  • Reliance on low personal injury rates as a primary safety indicator can be misleading and fail to capture the risk of catastrophic process safety incidents. A focus on process safety metrics is crucial.
  • Deficiencies in mechanical integrity programs, including inadequate maintenance, testing, and calibration of critical instrumentation, can lead to failures with catastrophic consequences. Equipment data sheets must be kept up-to-date.
  • Effective incident investigation systems are essential for capturing lessons learned and implementing needed changes to prevent future incidents. Near-misses and previous incidents should be thoroughly investigated.
  • A strong safety culture with a focus on process safety management is paramount for preventing major accidents. This includes encouraging reporting of incidents without fear of retaliation and ensuring that management models and enforces safety procedures.
  • Organizational changes (MOC) must be systematically reviewed to ensure safety is maintained.
  • Board-level oversight and accountability for process safety are crucial.
Sources / References
  1. U.S. Chemical Safety and Hazard Investigation Board. (2007). *Refinery Explosion and Fire (15 Killed, 180 Injured): BP Texas City, Texas, March 23, 2005 (Investigation Report No. 2005-04-I-TX)
BP Texas City Refinery Explosion aftermath showing the destruction of trailers

Image Source: US Chemical Safety Board

Analysis

The incident at the BP Texas City Refinery on March 23, 2005, was a culmination of numerous safety system deficiencies and organizational failures. The startup of the ISOM unit’s raffinate splitter section involved filling the tower with liquid. However, the level control valve on the tower was not functioning correctly, and feed was added for approximately three hours without liquid being removed. Contributing to this was a malfunctioning level transmitter (LT-5100) that provided an inaccurate level reading to the control system. Additionally, a high-level alarm (LSH-5020) failed to activate due to a corroded float.

As the tower overfilled, pressure increased, causing three pressure relief valves to open. These valves discharged a large quantity of flammable raffinate liquid into a blowdown drum, which was designed to handle vapors and small amounts of liquid but quickly overfilled. The blowdown drum was connected to a stack open to the atmosphere and was not equipped with a flare to safely combust flammable releases. The overfilled drum resulted in a geyser-like release of flammable liquid out of the blowdown stack.

The cascading liquid from the stack atomized into small droplets, enhancing evaporation and the formation of a large flammable vapor cloud at ground level. The source of ignition is believed to have been a nearby idling pickup truck. The resulting vapor cloud explosion generated significant blast pressure that caused widespread damage and fatalities. Tragically, many contract workers were located in temporary trailers situated very close to the ISOM unit and the blowdown drum, and these trailers offered little protection against the blast.

The CSB investigation revealed that prior to this catastrophic event, there were numerous warning signs, including at least eight serious hydrocarbon releases from the ISOM blowdown stack between 1994 and 2004, some of which resulted in fires. Most ISOM startups also experienced high liquid levels in the splitter tower. However, these incidents were not effectively investigated, and lessons were not learned or implemented to prevent a recurrence.

Furthermore, the investigation highlighted a systemic lack of focus on process safety at the Texas City refinery, driven in part by cost-cutting measures and a prioritization of personal safety metrics over process safety management. Audits and studies had identified serious safety problems at the refinery for years, but the companies response was ineffective. The placement of the trailers near the hazardous unit, despite existing (though inadequate) siting policies and previous hydrocarbon releases, underscored a broader organizational failure to adequately assess and mitigate major accident risks.

On February 11, 2018, at approximately 1:15 p.m. PST, a release of compressed hydrogen occurred from a tube trailer module operated by Air Products and Chemicals, Inc. The incident took place on Golden Springs Drive in Diamond Bar, California. The tube trailer module, mounted on a 2015 Cheetah Chassis Corporation chassis and towed by a 2014 Mack CXU613 truck tractor, contained 25 fully wrapped carbon fiber-reinforced aluminum-lined cylinders, with 24 of them fully loaded with approximately 240 kilograms of compressed hydrogen. The release led to a subsequent fire, activating pressure relief devices on 12 cylinders, releasing about 120 kilograms of hydrogen, which was likely consumed in the fire. The Los Angeles County Fire Department evacuated an estimated 1,400 to 2,000 people from the adjacent business district and nearby residential area. Equipment damages were estimated at $175,000.

Date
11/02/2018
Location
United States of America
Industry
Hydrogen Transportation
Substance
Hydrogen
Cause

The probable cause was the installation of an incorrectly rated pressure relief device in cylinder No. 14 by a requalification technician, which actuated during normal transportation and released high-pressure hydrogen.


Contributing factors included:


• The tube trailer module assembly contractor’s failure to sufficiently tighten compression fittings on the pressure relief device vent lines. These disassembled under the pressure of escaping gas, allowing a fire to develop inside the module and impinge on adjacent cylinders.


• Lack of a requirement for requalification inspectors to verify the pressure relief device pressure rating and to inspect for vent line assembly securement.

Consequence
  • Activation of PRDs on 12 cylinders, releasing approximately 120 kilograms of hydrogen.
  • Subsequent fire consuming the released hydrogen.
  • Evacuation of approximately 1,400 to 2,000 individuals from nearby areas.
  • Equipment damages estimated at $175,000.
  • No reported injuries or fatalities.
Injuries

None reported.

Fatalities

None reported.

Lessons Learned
  1. Emergency responder awareness is critical; training is needed for incidents involving hydrogen tube trailer modules.
  2. Requalification and inspection requirements must be improved to prevent similar incidents. This includes verifying PRD compatibility and vent line securement.
  3. Hydrogen tube trailer component design criteria need to be enhanced, particularly for PRD vent systems.
  4. The importance of verifying that PRDs of the correct pressure rating are used.
  5. The importance of ensuring that PRD venting equipment is inspected and tested.
Sources / References
  1. National Transportation Safety Board. 2019. Air Products and Chemicals, Inc. Tube Trailer Module Hydrogen Release and Subsequent Fire, Diamond Bar, California, February 11, 2018. Hazardous Materials Incident Report NTSB/HZM-19/02.
No featured image found

Analysis

The incident in Diamond Bar, California, on February 11, 2018, was initiated by the installation of an incorrectly rated pressure relief device (PRD) in cylinder No. 14. This PRD, designed to activate at 5,833 psi, was mistakenly installed instead of the required 10,000 psi PRD during a requalification inspection. During normal transportation, the incorrect PRD actuated, releasing high-pressure hydrogen. The force of the escaping gas caused the pressure relief device vent tubing to eject from its fitting because the compression fittings were not sufficiently tightened. This directed the hydrogen into the interior of the module, leading to a fire that damaged 21 of the cylinders.

The fire’s intensity caused six additional pressure relief device vent tubes to eject from improperly secured compression fittings, further escalating the situation

The Los Angeles County Fire Department (LACoFD) responders lacked familiarity with hydrogen tube trailer modules, which added to the initial confusion and challenges in managing the incident. The generic guidance in the Emergency Response Guidebook (ERG) Guide 115 did not adequately address the unique hazards associated with compressed hydrogen, further complicating the emergency response.

As a result of the incident, several safety recommendations were made to prevent similar occurrences in the future:
• The Pipeline and Hazardous Materials Safety Administration (PHMSA) was urged to revise the Emergency Response Guidebook (ERG) to include specific information about hazards and protective actions for hydrogen, as well as guidance for managing incidents involving fuel cell electric vehicles (FCEVs) and hydrogen fuelling infrastructure. 


• PHMSA was also recommended to revise hazardous materials special permits for transporting gases in manifolded horizontal cylinders. The revision would require that requalification inspections include verifying that PRDs of the correct pressure rating are used and that PRD venting equipment is inspected to ensure it can withstand forces generated by PRD actuation. 


• Additionally, PHMSA was advised to revise Title 49 Code of Federal Regulations Part 180, subpart C, “Requirements for Requalification of Specification Cylinders,” to ensure that inspectors verify PRD pressure ratings and inspect venting equipment. 


• PHMSA was encouraged to collaborate with the Compressed Gas Association (CGA) to develop design guidelines for tube trailer PRD vent systems. 


• The US Department of Energy, Pacific Northwest National Laboratory, was recommended to revise its hydrogen emergency responder training programs to include specific information and guidance on hazard recognition and firefighting related to tube trailers and FCEV fuelling infrastructure. 


• The Compressed Gas Association (CGA) was also advised to work with PHMSA to develop design guidelines for tube trailer PRD vent systems. 


These recommendations emphasise the need for improved training, stricter inspection protocols, and better design standards to enhance the safety of hydrogen transportation.

On March 3, 1991, a crude oil pipeline operated by Lakehead Pipeline Company (now Enbridge) ruptured near Grand Rapids, Minnesota. The failure resulted in the release of over 1.7 million gallons of crude oil into a wetland area and the Prairie River, a tributary of the Mississippi River. A local resident detected the odor of oil and alerted the fire department, leading to the evacuation of approximately 300 nearby residents as a precautionary measure. Fortunately, there were no reported injuries or fatalities.

Date
03/03/1991
Location
United States of America
Industry
Crude Oil Pipeline Transmission
Substance
Crude Oil
Cause

The specific cause of the pipeline rupture was not detailed in the available sources. However, historical data indicates that from the early 1970s to 1991, approximately 4 million gallons of oil had spilled from this pipeline, suggesting potential issues related to pipeline integrity or maintenance practices.

Consequence
  • Release of over 1.7 million gallons of crude oil into the environment.
  • Contamination of wetland areas and the Prairie River, posing risks to local ecosystems.
  • Evacuation of approximately 300 residents as a safety precaution.
Injuries

None reported.

Fatalities

None reported.

Lessons Learned
  • Pipeline Integrity Management: The incident underscores the necessity for rigorous inspection and maintenance programs to ensure pipeline integrity and prevent environmental contamination.
  • Emergency Response Preparedness: The prompt detection of the spill by a local resident and the subsequent evacuation highlight the importance of community awareness and effective emergency response plans in mitigating the impact of such incidents.
Sources / References
An image illustrating the environmental impact of the oil spill, with oil-contaminated water and affected vegetation. Source Reference: Marohn, K. (2021, March 3). 30 years later, echoes of largest inland oil spill remain in Line 3 fight. MPR News. Retrieved from https://www.mprnews.org/story/2021/03/03/30-years-ago-grand-rapids-oil-spill

An image illustrating the environmental impact of the oil spill, with oil-contaminated water and affected vegetation. Source: Marohn, K. (2021, March 3). 30 years later, echoes of largest inland oil spill remain in Line 3 fight. Image is a screengrab from a video shot by Harry Hutchins.

Analysis

The Lakehead Pipeline oil spill near Grand Rapids, Minnesota, on March 3, 1991, represents a significant environmental incident in the history of U.S. pipeline operations. The release of over 1.7 million gallons of crude oil into sensitive wetland areas and the Prairie River posed substantial threats to local ecosystems and water quality.

The recurrence of spills from this pipeline, totaling approximately 4 million gallons from the early 1970s to 1991, indicates systemic issues in pipeline integrity management. Factors such as corrosion, material defects, or inadequate maintenance practices may have contributed to these failures. This pattern of incidents emphasizes the critical need for comprehensive integrity management programs, including regular inspections, timely repairs, and the application of advanced monitoring technologies to detect and address potential vulnerabilities before they result in environmental harm.

The proactive response by the local community, particularly the individual who detected the oil odor and alerted authorities, played a crucial role in initiating emergency protocols and minimizing potential health risks. The evacuation of approximately 300 residents underscores the importance of effective communication and coordination between pipeline operators, emergency responders, and the public. Establishing clear emergency response plans and conducting regular drills can enhance preparedness and ensure swift action during such events.

In the aftermath of the spill, extensive cleanup efforts were undertaken to recover the released oil and remediate the affected environments. The incident served as a catalyst for regulatory reviews and the strengthening of safety standards within the pipeline industry. Implementing more stringent regulations and oversight can drive improvements in pipeline design, operation, and maintenance, thereby reducing the likelihood of future spills and protecting environmental and public health.

Overall, the Lakehead Pipeline oil spill highlights the complex challenges associated with transporting hazardous materials and the imperative for diligent safety practices, robust infrastructure, and collaborative emergency response mechanisms to prevent and mitigate the impacts of industrial incidents.

On March 2, 1974, a 30-inch natural gas transmission pipeline operated by Michigan-Wisconsin Pipeline Company failed under a road near Monroe, Louisiana. The pipeline was operating at a pressure of 797 pounds per square inch (psi) within a 34-inch casing pipe. The rupture resulted in a significant release of natural gas, leading to a fire that burned approximately 10 acres of forested area. Fortunately, there were no injuries or fatalities reported.

Date
02/03/1974
Location
United States of America
Industry
Natural Gas Transmission
Substance
Natural Gas
Cause

The investigation identified a substandard girth weld as the primary cause of the pipeline failure. Additionally, the automatic valves on the pipeline failed to close upon detecting a pressure drop, which contributed to the extent of the incident.

Consequence

Approximately 10 acres of forest were burned due to the fire resulting from the ignited gas release.

Injuries

None reported.

Fatalities

None reported.

Lessons Learned
  • Importance of Weld Quality: Ensuring the integrity of girth welds is crucial in preventing pipeline failures.
  • Functionality of Safety Systems: The failure of automatic valves to close upon detecting a pressure drop highlighted the need for regular maintenance and testing of safety systems to ensure proper operation during emergencies.
Sources / References
  1. National Transportation Safety Board. (1974). Pipeline Accident Report: Natural Gas Pipeline Rupture and Subsequent Explosion, St. Helena, California, March 2, 1974.
  2. U.S. Department of Transportation, Pipeline and Hazardous Materials Safety Administration. (2003). Integrity Characteristics of Vintage Pipelines.
No featured image found

Analysis

The pipeline rupture near Monroe, Louisiana, on March 2, 1974, underscores critical vulnerabilities in pipeline construction and safety mechanisms. The failure originated from a substandard girth weld, a crucial joint connecting sections of the pipeline. Such weld defects can arise from inadequate welding techniques, insufficient inspection protocols, or material inconsistencies. This incident emphasizes the necessity for rigorous welding standards and comprehensive inspection regimes during pipeline construction and maintenance phases.

Compounding the initial mechanical failure was the malfunction of the pipeline’s automatic valve system. These valves are designed to detect anomalies, such as sudden pressure drops, and to isolate affected pipeline sections to prevent extensive gas release and potential ignition. In this case, the valves failed to activate, allowing the uncontained release of natural gas, which subsequently ignited and resulted in a fire that consumed 10 acres of forested land. This malfunction highlights the imperative for regular testing, maintenance, and, if necessary, upgrading of safety systems to ensure their reliability during critical moments.

On March 4, 1965, at approximately 6:03 a.m., a 24-inch high-pressure natural gas pipeline owned by Tennessee Gas Pipeline Company ruptured near Natchitoches, Louisiana. The resulting explosion created a massive fireball that devastated a 13-acre residential area, leading to significant loss of life and property damage.

Date
04/03/1965
Location
United States of America
Industry
Natural Gas Transmission
Substance
Natural Gas
Cause

The rupture was attributed to stress corrosion cracking in the pipeline, exacerbated by inadequate maintenance and inspection protocols. The pipeline’s proximity to residential areas without sufficient safety measures contributed to the severity of the incident.

Consequence
  • Number of Injuries: At least 9 individuals sustained burns and other injuries, some severe.
  • Number of Fatalities: 17 people, including nine children, lost their lives.
  • Property Damage: Five houses were destroyed, vehicles were melted, and the explosion left a large crater at the rupture site.
Injuries

9 known injuries.

Fatalities

17 fatalities including 9 children.

Lessons Learned

The disaster underscored the critical need for stringent safety regulations in the operation and maintenance of natural gas pipelines, especially those near populated areas. It highlighted the importance of regular inspections, prompt addressing of pipeline integrity issues, and the implementation of comprehensive safety standards to protect communities.

Sources / References
  1. Louisiana Department of Energy and Natural Resources. “Pipeline Safety Program History.”
  2. The American Presidency Project. “Statement by the President Upon Signing the Natural Gas Pipeline Safety Act of 1968.”
No featured image found

Analysis

The Natchitoches explosion remains one of the most catastrophic pipeline failures in U.S. history. The 24-inch pipeline, transporting natural gas at high pressure, ruptured due to stress corrosion cracking—a phenomenon where pipelines deteriorate over time under stress and corrosive conditions. The explosion’s force was so immense that it gutted a 13-acre area, melted cars, rocks, and resulted in a significant crater. In the aftermath, the incident prompted legislative action, leading to the enactment of the Natural Gas Pipeline Safety Act of 1968, which established federal safety standards for pipeline transportation.