Washington, DC, January 26, 2006 - The United States Chemical Safety and Hazard Investigation Board (CSB) today issued a Safety Bulletin, warning acetylene gas producers to take special precautions in handling this potentially dangerous product. The Safety Bulletin follows a year-long investigation into a powerful explosion that killed three workers and injured a fourth at the Acetylene Services Company (ASCO) in Perth Amboy, New Jersey, on January 25, 2005.
The CSB has also issued and posted on its web site, www.CSB.gov, a Video Safety Bulletin on the incident.
The Safety Bulletins contain safe handling guidelines as well as CSB findings and recommendations from the ASCO investigation. CSB investigators found that a combination of factors resulted in acetylene flowing backward from the company's acetylene production generator through water pipes and out of an open drain valve into a shed. The highly-explosive gas built up to a dangerous level and likely was ignited when it reached the hot surface of the shed's propane space heater. Three workers shoveling snow near the shed -- constructed of wood panels built around six recycled-water tanks -- were killed in the powerful blast, and a fourth worker was seriously injured.
CSB Board Member Gary L. Visscher, who accompanied the investigation team to the scene when the accident occurred, said, "The tragic accident at ASCO points to how important it is to have comprehensive operating procedures, to train workers in those procedures, and to have effective measures in place to prevent the backflow of flammable gases. The CSB is urging acetylene producers and handlers to review the Safety Bulletin and examine their systems and safety procedures to prevent this kind of accident from occurring again."
The Safety Bulletin notes that water pipes at the facility ran between the acetylene generator and large outdoor tanks attached to the shed, and included a drain valve. Water pressure and a safety device called a check valve normally prevented acetylene from backing into the shed. Operators began generating acetylene the morning of January 25, 2005, using water from the city supply. CSB investigators concluded that this supply was shut off with the apparent intention of switching to the recycled-water supply. The recycled-water valve was opened, but for reasons that could not be conclusively determined, operators did not actually switch on the flow of recycled water. This left an open path from the acetylene generator to the shed's drain valve, which had been left open the night before to prevent the pipes from freezing in the cold weather. The check valve should have prevented the acetylene from flowing backwards through the pipes, but CSB investigators determined the valve contained a design flaw that made it susceptible to failure. Rather than seating properly and sealing off acetylene, a rubber plug in the valve hung up at an angle, allowing acetylene to easily flow backwards through the check valve.
Investigations Manager Steve Selk said, "Several situations combined to cause this tragedy, including the unsafe location of the pipe drain, a lack of procedures that allowed the recycled-water valve to be opened without water actually running through the pipe, and the check valve design that made it susceptible to failure. Operators should review our Safety Bulletin and focus attention on hazards that can be deadly."
The CSB Safety Bulletin urges operators to maintain up-to-date operating procedures; use checklists; train on the procedures; relocate vents to safe, outside locations; test critical valves and ensure that enclosures, such as sheds that contain hazardous materials, meet national fire code standards.
In addition, the Board issued formal recommendations to the companies involved and to the Occupational Safety and Health Administration (OSHA). The CSB recommended ASCO implement an effective Process Safety Management program and include written checklists that are understood by workers; Rexarc International, Inc., the manufacturer of the check valve, was urged to inform other customers about the ASCO incident, recommend actions to ensure the valves are working safely, and to replace check valves in service with ones that will operate more reliably. The CSB recommended that OSHA remove obsolete information from its Acetylene Standard (29 CFR 1910.102), and update it.
The CSB is an independent federal agency charged with investigating industrial chemical accidents. The agency's board members are appointed by the president and confirmed by the Senate. CSB investigations look into all aspects of chemical accidents, including physical causes such as equipment failure as well as inadequacies in safety management systems, regulations, and industry standards.
The Board does not issue citations or fines but does make safety recommendations to plants, industry organizations, labor groups, and regulatory agencies such as OSHA and EPA. Visit our website, www.csb.gov.
For more information, contact:
Sandy Gilmour, 202-261-7614 or cell 202-251-5496; Public Affairs Specialist Lindsey Heyl, 202-261-3614 or cell 202-725-2204; Public Affairs Specialist Kara Wenzel, 202-261-7642, cell 202-577-8448; or Director of Public Affairs Dr. Daniel Horowitz, 202-261-7613 or cell 202-441-6074.