This chapter focuses on accidents that occurred because equipment was not adequately prepared for maintenance. Sometimes the equipment was not isolated from hazardous materials, sometimes it was not identified correctly and so the wrong equipment was opened up, and sometimes hazardous materials were not removed. Various incidents have been outlined that reflect the failure in maintenance, human errors, or equipment itself. Summary of methods for maintenance of isolation is also provided to prevent causes of errors due to isolation failures. When an electrical supply is isolated, it is normal practice to check that the right switches have been locked or fuses removed by trying to start the equipment that has been isolated. On several occasions, maintenance teams have not realized that by isolating a circuit, they have also isolated equipment that was still needed. Need for tagging is highlighted when the wrong pipeline or piece of equipment has been broken into. Many accidents have occurred because equipment, though isolated correctly, was not completely freed from hazardous materials or because the pressure inside it was not completely blown off and the workers carrying out the repair were not made aware of this. Therefore it is usual to test for the presence of flammable gas or vapor with a combustible gas detector before maintenance, especially welding or other hot work is allowed to start. This chapter also describes incidents that occurred because of loopholes in the procedure for issuing work permits or because the procedure was not followed, and also points out the formal procedure to be followed.
During the four decades that the Fukushima Daiichi Nuclear Power Station was in operation, nuclear safety authorities and nuclear power plant owners in several countries were establishing requirements and configuring nuclear power plants in ways that could potentially have saved the Fukushima Daiichi nuclear station from disaster had they been heeded. In particular, some regulatory bodies outside of Japan reassessed the safety of installations in the event of extreme flood hazards, a station blackout, and the loss of the ultimate heat sink. In the view of safety experts participating in such assessments, had Japan acted on these developments, the plant could have survived the tsunami that struck in March 2011.
Still Going Wrong!: Case Histories Of Process Plant Disasters And How They Could Have Been Avoided.p
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