Washington, DC, September 16, 2004 - The U.S. Chemical Safety and Hazard Investigation Board (CSB) today released its final report examining the causes of the February 2003 explosion and fire at a plating chemicals manufacturing facility in Cranston, Rhode Island. The report determined several root and contributing causes of the accident and made recommendations to the company and industrial safety organizations.
The accident took place at a manufacturing plant owned by Technic Inc., a company that produces chemicals and equipment for plating precious and non-precious metals in the electronics and jewelry industries. On the morning of February 7, 2003, a violent chemical reaction occurred inside a vent collection system used to carry waste gases and particulates to a pollution control device known as a scrubber.
The resulting explosion and fire critically injured one employee, sent 18 others to the hospital for medical evaluation, and prompted an evacuation of the surrounding community. The critically injured employee suffered permanent eye damage and chemical burns on his face and upper body.
The vent collection system consists of interconnected segments of polyvinylchloride (PVC) duct suspended about 20 feet above the floor of the plant. The system has dozens of pieces of equipment connected to it, including chemical reactors, mixing tanks, storage vessels, and packaging equipment. The equipment handles a wide variety of chemicals including silver nitrate and potassium silver cyanide.
The CSB investigation uncovered two significant root causes of the accident. The first was the lack of a review of hazards when the company installed the vent collection system handling exhaust from multiple processes. The report found that Technic did hire a ventilation consultant during the system design and installation and also had staff chemists who could have assessed process chemical compatibility. However, the company did not have management procedures in place to lead to a review of the hazards of incompatible chemicals in the ventilation system. The flawed design of the ventilation system led to conditions where reactive and explosive substances could accumulate inside, CSB investigators said.
The second root cause was the lack of a system for identifying hazards when making modifications to facility processes and equipment referred to in the chemical industry as "management of change." In this case, Technic personnel modified the vent collection system by connecting new process equipment without analyzing potential hazards or reviewing the changes with appropriate technical personnel.
"Good engineering practices and the management of change in chemical facilities are essential for the prevention of uncontrolled, violent chemical reactions," CSB Chairman Carolyn Merritt said. "Each time a piece of equipment is added or moved into a process system, it is important to identify and control potential hazards before any production begins."
CSB investigators detailed two possible scenarios that could account for the initial explosion. Based on those scenarios, the explosion likely involved either a violent reaction of a shock-sensitive silver compound or alternatively a violent reaction between silver nitrate and another substance. Silver nitrate, a chemical that was sometimes carried into the vent collection system, is a strong oxidizing agent that can react violently with various other materials. Silver nitrate can also react with some chemicals to form shock-sensitive, explosive silver compounds. A small amount of a shock-sensitive silver compound was in fact detected inside the vent collection system after the accident; such compounds could have caused an explosion if exposed to a very small amount of energy.
Either of the two scenarios was considered plausible because both silver nitrate and various organic compounds were introduced into the vent collection system over the years, investigators said. Fire and blast damage inside the vent system made it difficult to determine the exact initiating event for the explosion. The report noted that the ventilation system had not been cleaned internally since 1996.
CSB investigators noted some problems with the emergency response to the accident. Neither the company nor the Cranston Fire Department adequately planned for a chemical accident response of this type. The fire department was unfamiliar with the Technic facility, its management personnel, and its hazards.
To aid in prevention of similar incidents, the CSB made recommendations to Technic, the National Fire Protection Association (NFPA), the American Industrial Hygiene Association (AIHA), and the American Conference of Governmental Industrial Hygienists (ACGIH). The Board urged the company to implement formal process safety review procedures and revise emergency response plans with the assistance of the Cranston Fire Department. The Board also emphasized the need for industrial safety organizations to provide companies with additional guidance on how to evaluate potential incompatibilities when chemicals are intermixed in ventilation systems.
The report on the explosion at Technic Inc., which was approved by the full Board in a written vote, is available from the agency's web site, CSB.gov.
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.
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. Further information about the CSB is available from www.csb.gov.
For more information, contact Daniel Horowitz at 202-261-7613 / 202-441-6074 (cell) or Sandy Gilmour at 202-261-7614 / 202-251-5496 (cell).