A specialized rubber manufacturing plant experienced leakage of a hexane solution from a pump discharge flange during use. The hexane vapor was ignited by a st atic electricity spark and a fire occurred. Apparently, the flange was loosened by vibrations from the pump.Routine operations were being carried out on site at the time of the accident.
The operation involved the transfer of a hexane solution from an un-reacted raw material recovery tank to the washing process through the outlet of the first flange of the pump. The hexane solution
leaked, ignited, and burned. The financial costs of recovery and lost production were significant.
Causes
The cause of the accident was a loose flange that resulted in leakage of a flammable substance. During the operation, a previously undetected cavitation in the pump produced significant vibration
which loosened the flange. As a cause of the ignition it was considered that the hexane was charged when it spouted from the flange, and static electricity was discharged; then hexane vapor ignited
and a fire occurred.
It was considered that the vibration might have been intensified by the passage of an insoluble polymer lump through the pump, a malformation in the substance generated on the piping wall. In addition, a reducer connected a 3-inch (~75mm) flange of the discharge pump to 6-inch (~150mm) piping. The looseness of this flange might have been accelerated when the force
of vibration was added on the piping.
Lessons learned
Vibrating equipment can increase potential for stress fractures and gaps from loosely fitting interfaces, all of which can be sources of leaks that, if undetected, may result in an accident. It is necessary to pay sufficient attention to vibrating equipment, especially pumps that may be found in many processes throughout the site. Control measures to mitigate potential risks could include regularly scheduled inspections in line with existing technical standards or in-house experience, particular attention to small-bore piping (vulnerable to fatigue), installation of a vibration monitor to detect and locate abnormal vibration patterns, as well as other measures available in guidance
on vibrations from numerous sources.
Source: European Commission
The operation involved the transfer of a hexane solution from an un-reacted raw material recovery tank to the washing process through the outlet of the first flange of the pump. The hexane solution
leaked, ignited, and burned. The financial costs of recovery and lost production were significant.
Causes
The cause of the accident was a loose flange that resulted in leakage of a flammable substance. During the operation, a previously undetected cavitation in the pump produced significant vibration
which loosened the flange. As a cause of the ignition it was considered that the hexane was charged when it spouted from the flange, and static electricity was discharged; then hexane vapor ignited
and a fire occurred.
It was considered that the vibration might have been intensified by the passage of an insoluble polymer lump through the pump, a malformation in the substance generated on the piping wall. In addition, a reducer connected a 3-inch (~75mm) flange of the discharge pump to 6-inch (~150mm) piping. The looseness of this flange might have been accelerated when the force
of vibration was added on the piping.
Lessons learned
Vibrating equipment can increase potential for stress fractures and gaps from loosely fitting interfaces, all of which can be sources of leaks that, if undetected, may result in an accident. It is necessary to pay sufficient attention to vibrating equipment, especially pumps that may be found in many processes throughout the site. Control measures to mitigate potential risks could include regularly scheduled inspections in line with existing technical standards or in-house experience, particular attention to small-bore piping (vulnerable to fatigue), installation of a vibration monitor to detect and locate abnormal vibration patterns, as well as other measures available in guidance
on vibrations from numerous sources.
Source: European Commission
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