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Concept Sciences Hydroxylamine Explosion

Overview

On February 19, 1999, a process vessel containing several hundred pounds of hydroxylamine exploded at the Concept Sciences, Inc. production facility near Allentown, Pennsylvania. CSI was producing its first commercial batch of 50 wt-percent hydroxylamine solution at the new facility. After distillation was shut down, the hydroxylamine in the process tank and associated piping explosively decomposed, most likely due to high concentration and temperature. Four CSI employees and one employee of an adjacent business were killed, and 14 people were injured.

Incident Snapshot

Field Value
Facility / Company Concept Sciences, Inc. (CSI)
Location Hanover Township, Lehigh County, Pennsylvania; near Allentown, Pennsylvania
Incident Date 02/19/1999
Investigation Status The CSB approved a Case Study on this incident on February 1, 2002.
Accident Type Reactive Incident
Final Report Release Date 02/01/2002

What Happened

  • CSI began its first distillation to produce 50 wt-percent HA in the new facility on Monday afternoon, February 15, 1999.
  • The charge tank contained approximately 9,000 pounds of 30 wt-percent HA.
  • By Tuesday evening, the concentration of liquid solution in the charge tank was approximately 48 wt-percent, and the product was being collected in the forerun tank.
  • The process was shut down Tuesday evening for maintenance when it was determined that water had leaked into the charge tank through broken tubes in the heater column.
  • The necessary repairs were made by Thursday afternoon, and the distillation process was restarted.
  • At 11:15 pm, the concentration of liquid solution in the charge tank was 56 wt-percent, and the concentration of the material collected was 15 wt-percent.
  • The distillation continued until approximately 11:30 pm that evening.
  • On Friday, February 19, a 1.5-inch feed line to the heater column was replaced with a 2-inch line, which delayed startup until later in the morning.
  • The concentration of liquid solution in the charge tank at that time was about 57 wt-percent HA.
  • Between 7:00 and 7:15 pm, the concentration of liquid solution in the charge tank was recorded as 86 wt-percent HA.
  • At approximately 7:45 pm, the still was shut down and cleaned with 30 percent HA to wash away crystals that may have formed.
  • The second phase of distillation was never started.
  • A manufacturing and engineering supervisor was called at his home and arrived at the facility shortly after 8:00 pm.
  • The explosion occurred at 8:14 pm.

Facility and Process Context

  • CSI leased approximately 20,000 square feet in a multiple-tenant building and began to set up the production facility.
  • CSI was located in a multiple-tenant building within a suburban industrial park.
  • The original siting location considered by CSI was described by Ashland as an office/commercial type building connected in a strip to other buildings.
  • CSI was producing its first batch of 50 wt-percent HA solution at the new facility on the day of the incident.
  • The process involved distillation of an aqueous solution of hydroxylamine and potassium sulfate.
  • The system included a vacuum distillation system with a glass column, remote water heater, glass condenser, remote chiller, vacuum pump, charge tank, forerun tank, and final product tank.
  • The process used a 1.5-inch feed line to the heater column that was replaced with a 2-inch line on the day of the incident.

Consequences

  • Four CSI employees and one employee of an adjacent business were killed.
  • 14 people were injured.
  • Two CSI employees survived the blast with moderate-to-serious injuries.
  • Four people in nearby buildings were injured.
  • Six firefighters and two security guards suffered minor injuries during emergency response efforts.
  • A cloud of chemical residue dispersed downwind of the site.
  • Liquid potassium hydroxide solution drained from two onsite storage tanks onto an adjacent parking lot.
  • The production facility was extensively damaged.
  • The explosion also caused significant damage to other buildings in the Lehigh Valley Industrial Park and shattered windows in several nearby homes.
  • The explosion damaged 10 buildings within the Lehigh Valley Industrial Park and several local residences.
  • A toy vending machine business adjacent to and in the same building as CSI and a package delivery service facility across the street received significant structural damage.
  • A nearby daycare center had minor structural damage.
  • Most of the residential damage was limited to broken windows.
  • Fire damage was primarily limited to CSI’s raw materials storage area.
  • A crater approximately 6 feet wide, 26 feet long, and 16 inches deep was found in the concrete floor directly below where the charge tank had been located.
  • The second phase of distillation was never started.
  • The production facility was extensively damaged.
  • Because of the lack of batch records, it was not possible to determine the exact amount of HA in the charge tank at the time of the explosion.

Key Findings

Immediate Causes

  • The HA in the process tank and associated piping explosively decomposed, most likely due to high concentration and temperature.
  • Any of several sequences of events could have caused this incident–addition of excessive heat to the distillation system, physical impacts from partial or total collapse of the glass equipment, or inadvertent introduction of impurities.
  • Friction may have heated the mixture as it passed through the pump that supplied the heating column. With the HA at a high concentration, this source of heat could have caused an explosion within the charge tank or the feed line to the tank.

Contributing Factors

  • HA crystals and solutions are known to explosively decompose at high concentrations (85 wt-percent; Koseki and Iwata, 2001).
  • Heating and the presence of contaminants can accelerate decomposition.
  • CSI management knew from laboratory distillations that crystals formed with HA concentrations greater than 80 wt-percent.
  • CSI’s material safety data sheet stated: Danger of fire and explosion exists as water is removed or evaporated and HA concentration approaches levels in excess of about 70%.
  • CSI’s HA production process, as designed, concentrated HA in a liquid solution to a level in excess of 85 wt-percent.
  • Only sketches and basic process flow diagrams were developed; there were no standard engineering drawings.
  • Operating procedures provided only rudimentary information.
  • CSI purchased equipment before it had conducted a formal engineering design review for the specific manufacturing process.
  • CSI’s design and safety review was inadequate given the hazards of highly concentrated HA.
  • CSI performed a “What If” PHA, which was reported in a one-page document, but it did not adequately address the prevention or consequences of events that could trigger an explosion of high concentrations of HA.
  • The PHA recognized the potential danger of the process and identified safeguards, such as remote control operation, blowout walls, and shielding for protecting employees if foreseeable hazards were realized; however, CSI did not implement any of these safeguards.
  • The existing system of siting approval by local authorities allowed a highly hazardous facility to be inappropriately located in a light industrial park.

Organizational and Systemic Factors

  • CSI’s process safety management systems were insufficient to properly address the hazards inherent in its HA manufacturing process and to determine whether these hazards presented substantial risks.
  • Inadequate collection and analysis of process safety information contributed to CSI’s failure to recognize specific explosion hazards.
  • Basic process safety and chemical engineering practices–such as process design reviews, hazard analyses, corrective actions, and reviews by appropriate technical experts–were not adequately implemented.
  • The development, understanding, and application of process safety information during process design was inadequate for managing the explosive decomposition hazard of HA.
  • This knowledge was not adequately translated into the process design, operating procedures, mitigative measures, or precautionary instructions for process operators.
  • CSI’s process safety management system was inadequate for managing the explosive decomposition hazard of HA.
  • CSI’s process safety management systems were insufficient to properly address the hazards inherent in its HA manufacturing process and to determine whether these hazards presented substantial risks.

Failed Safeguards or Barrier Breakdowns

  • The process safety information was not adequately compiled, analyzed, and updated before initiating design and construction.
  • There were no standard engineering drawings.
  • Operating procedures provided only rudimentary information.
  • An adequate reactive chemical hazard evaluation and process hazard analysis was not conducted.
  • CSI did not implement the safeguards identified in the PHA, such as remote control operation, blowout walls, and shielding.
  • CSI did not alert the local township to the process hazards associated with HA production.
  • The LEPC was not notified of the CSI siting issue.

Recommendations

  1. Recommendation 1 — Recipient: Not specified. Status: Not specified. Summary: No recommendation details were provided in the source JSON.

Key Engineering Lessons

  • Reactive chemical processes require a formal engineering design review and adequate reactive chemical hazard evaluation before equipment purchase and startup.
  • Process hazard analysis findings must be translated into implemented safeguards, not only identified on paper.
  • Process safety information, operating procedures, and engineering drawings must be sufficiently developed and maintained to support safe operation of highly hazardous chemistry.
  • Concentration and temperature control are critical for hydroxylamine service because high concentrations can lead to explosive decomposition.

Source Notes

  • Priority 1 final report used as the authoritative source where it conflicted with lower-priority material.
  • The final report identifies the incident as a catastrophic hydroxylamine explosion at CSI in Hanover Township, Lehigh County, Pennsylvania, near Allentown.
  • The supporting document about CSB reporting rule comments was not used for incident-specific facts because it is not an investigation of this incident.

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