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ESDV Failure Due to Toggle Orientation

Incident Description:

  • An ESD (Emergency Shutdown) valve’s hydraulic pump toggle orientation may have contributed to the amount of product released during the following incident. The incident itself was caused from other factors, however.
  • The company discovered a hydrocarbon condensate leak.
  • Data shows that the pipeline pressure dropped below the high/low pressure pilot settings, and two ESD valves upstream of the leak should have closed but did not. This would not have prevented the leak but could have allowed a quicker response from operations and resulted in less product on the ground. Subsequent investigation proved that if latch toggles are not left in the correct position, there is a chance their action could be delayed or prevented.
Contributing Factors / Event Learnings:
  • There was not enough importance placed on the toggle orientation because historically it had not been a problem.
  • There are many different manufacturers and models of pumps and toggles. Most are similar; however, their age, past maintenance and environmental factors can play a role in their effectiveness.
Required Actions:
  • Raise awareness of the potential “sticking” problem with hydraulic latch block toggles if left in the incorrect position.
  • Review all installations to ensure all hydraulic latch toggles are always left in the correct orientation.
  • This awareness may also apply to any toggle that is required to mechanically change position when tripped, including air or fuel gas (pneumatic) installations.

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