CSB Safety Advisory Calls for Validation of Chlorine Transfer Hoses

December 4, 2002

(Washington, DC - December 4, 2002) Finding that the use of an incorrect hose led to an August 2002 chlorine leak near St. Louis, a new safety advisory issued today by the U.S. Chemical Safety Board (CSB) calls on other chlorine users to verify the materials of construction of their chlorine transfer hoses.

The advisory grows out of an August 14, 2002, chlorine release at DPC Enterprises in Festus, Missouri. In that incident, a transfer hose failed catastrophically during the unloading of a chlorine rail car. Due to the malfunction of an automatic shutdown system, the leak continued unabated for several hours, eventually causing the release of about 48,000 pounds of toxic chlorine gas. Sixty-three people, including workers and nearby residents, sought hospital treatment as the result of the leak.

Subsequent analysis showed that the transfer hose was constructed with braided stainless steel -- a material that is not recommended for chlorine service -- despite documentation from the hose distributor indicating that the hose was made of a chlorine-resistant alloy. The two kinds of braiding are visually indistinguishable. The hose that failed had evidently been degraded by the flow of chlorine, which is a strong corrosive, and had been in service for just 59 days when the failure occurred.

"Chlorine handlers should ensure that any nonmetallic-lined chlorine transfer hoses they use are constructed with the appropriate structural braiding layer, either PVDF monofilament or Hastelloy C-276," stated CSB lead investigator John Murphy, citing a recommended safety practice of the Chlorine Institute. "Nondestructive testing methods such as X-ray fluorescence can be used to positively differentiate between Hastelloy C-276, the intended material, and 316 L stainless steel, the use of which can lead to catastrophic hose failure."

"The incident at DPC Enterprises underscores the very serious consequences that can ensue from chlorine hose rupture," according to CSB Chairman Carolyn W. Merritt. "Chlorine users should treat this incident as a wake-up call to verify that their hoses are what they think they are. The Board requests that any person who determines that a chlorine transfer hose has been misidentified - or who experiences a related hose failure -- please contact the agency as soon as possible."

The Chemical Safety Board has not completed its final report on the DPC incident. That report, expected in the next several months, will include a final determination of causes together with safety recommendations to prevent recurrences. The CSB is providing this Safety Advisory, available from www.csb.gov, as a precautionary measure for chlorine users. For further information contact Giby Joseph at (202) 261-7633.

Safety Advisory - Chlorine Transfer Hose Failure PAGE LAST UPDATED: December 4, 2002

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