Abstract: At 10:00 a.m. on September 13, 2014, four employees were assigned to remove and replace a gear box operator of a valve at an oil rig platform in the Gulf of Mexico. The employees arrived by boat to the platform during high tide. After waiting an approximate hour for the tide to recede, they were instructed to proceed with removal of the gear box operator despite low tide not being set to come for another hour. As the new gear box operator was put into place and the employees were preparing to install its bolts, it was determined that the adaptor plate needed to be removed to appropriately align the equipment for installation. While the valve was under 800 psi of pressure, the employees began removing the eight hex bolts that held the adaptor plate to the valve. During removal of the bolts, the adapter plate and valve stem blew off and struck Employee #1, who fell into the Gulf of Mexico and drowned. Employees #2 and #3 were also thrown backwards from the pressure release, suffering hearing loss and minor contusions.