Abstract: At approximately 9:30 a.m., on October 3, 2012, Employees #1 and #2 of Brahma Group Inc. DBA Brahma Group West became injured, one fatally, while performing weld checks inside a vertical pressure vessel (Cation Tank A). The pressure vessel involved in the accident, when in use, contains acid and water mixture which is used to ionically remove minerals from the water as part of water purification process with a rubberized coating on the interior to prevent corrosion. It was determined that the tank had been leaking. The tank was then emptied, purged, and the repair was initiated to remove some of the rubber coating from the false bottom allowing re-welding of the false bottom to reseal it and stop the leakage. At the time of the accident, the new welds on the false bottom were completed and the area under the false bottom was being pressurized with compressed air (approximately 120psi) while Employees #1 and #2 were checking for leaks above. A section of the false bottom near where Employees #1 and #2 were standing, exploded violently, and ruptured, killing Employee #1, a welder, and seriously injuring Employee #2, a superintendent.