Oleum release incident - CSB findings

The CSB has released its final report on the uncontrolled oleum release from INDSPEC Chemical Corporation in Petrolia, Pennsylvania, which forced the evacuation of three surrounding towns in October 2008.Oleum was released when a tank transfer operation was left unattended during weekend operations and an oleum storage tank overflowed.
The CSB investigation has determined that the normal power supply for the three oleum transfer pumps was equipped with a safety interlock, which would automatically shut off the flow of oleum when the receiving tank was full, thus preventing a dangerous overflow. However, the oleum storage building also had an auxiliary or 'emergency' power supply that had been installed in the late 1970s. It was originally intended as a temporary measure to keep the pumps functioning during interruptions of the normal power supply but eventually the emergency power supply became a permanent fixture. Facility management never installed interlocks for the emergency power and written operating procedures did not address how or when the emergency power supply should be used.
The CSB case study report identifies four key safety lessons for companies:
- In the 1980s, the facility changed the structure of the emergency power supply from temporary wiring to permanent conduit. The facility did not evaluate the significance of this change.
- The facility installed the emergency power supply without the engineering controls that already existed on the normal power supply.
-The facility's storage system design required operators to transfer oleum on the weekend to ensure operations were unaffected during the week. Operators used a work practice developed years earlier to transfer oleum using two pumps concurrently. This work practice was never recorded in written operating procedures.Management must remain vigilant in evaluating how work is actually performed.
- The facility never included information on the emergency power supply in piping and instrumentation diagrams and written operating procedures. Personnel hazard assessment (PHA) teams were therefore unable to evaluate the consequences of emergency power supply use.
Read the report in this link