Hidden Safety Systems Failures and their Contribution to Catastrophic Events: Case Studies from the Energy Industry

It is accepted that incremental advances in technology have made equipment increasingly safer to operate across all industries. Although safety improvements are commendable, there are instances where the failure of safety systems has contributed to catastrophic events. Using two case studies from the energy industry, we identify the failures, hidden to the operators, that contributed to serious incidents. In the first example involving an explosion at the Upper Big Branch Mine in Montcoal, West Virginia, the failure of the ventilation systems resulted in the build-up of explosive gas and dust which was then exposed to a source of ignition. In the second example involving a gas pipeline explosion in San Bruno, California, a fault in the redundant power supplies resulted in a pipeline pressure increase which was a contributing factor to the subsequent explosion. We explore the possibility that the growing complexity of equipment used to deliver advances in performance, and the correspondingly intricate safety systems that are required, is increasing the likelihood of these hidden failures. The presence of the failures may be known to select company employees but are not communicated to the equipment operators, hence our emphasis on the `hidden' aspects of their failures. The main objective of our paper is to identify instances of safety systems faults that acted as contributory causes in catastrophic incidents. In doing so, we highlight how more effort is required for thorough testing of the function of safety systems and the consequences of associated failures. We argue that an improved focus on design, testing, communication and operator training will do much to avoid the types of safety systems faults that have contributed to the disasters detailed in our case studies.

Keywords: Safety systems, Energy, Transmission, Mining, Gas pipeline, Hidden failures, Complex equipment.