Occupational deaths from Similar Causes; Why?

Understanding why incidents re-occur from similar causes despite the previous experiences, lessons and available tools to ensure that they do not happen again has been a cause of concern for company management for years and different reasons have been attributed to this issue. In recent past, below are few examples of incidents from similar causes. On 25 January 2012, during the pre-mob inspection of a pile load tester pump by a DIL pile rig operator (Mechanical-24yrs old) with his Supervisor, the unit was put under pressure three times successfully but there was no movement of the pump piston. The pump was put under pressure the fourth time with a declared pressure of 500 bars, the pile load tester flange suddenly gave way and caused several severe injuries to the operator. He was confirmed dead at around 18h30. The unit was brand new with test certificate; IP was trained for it and note that the design pressure of the pile load tester was 690bars. In addition, when the unit failed, the 25 out of 26 bolts of the flange cut off while the last one had its nut pulled out. On 15 May 2017, a fatal accident occurred when an analyzer engineer removed the cover on an explosion-proof enclosure as part of the routine task for the day. The ~5.5kg weighing threaded cover and with a 14 inches in diameter was propelled forcefully from the enclosure as the Engineer unscrewed it inflicting a fatal head injury. The pressure inside the enclosure from leaking sample gas or instrument air components caused the forceful propulsion of the enclosure cover. There was no gauge or indicator on the enclosure to monitor the internal pressure inside the enclosure and there was no means to relieve internal pressure (http://www.safteng.net/images/2017_Posts_Pics/CVXIndustryAlertJune2017.pdf).