tragic event were identified , ranging from Design Issues , Safety Priority and Poor Safety Culture , to Improper Isolation and Work Permits . Nevertheless , the most likely source of the hydrocarbon release , that caused the initial explosion , per the inquiry , was an unsecured blind flange ( not fully tightened ) and the upstream pressure safety valve ( PSV ), which had been removed for maintenance . Additionally , the inadequacies of both the work permit and the shift handover procedures gave the wrong impression to the operator that it was safe to restart the pump .
● What if the blind flange that caused the initial explosion at the Piper Alpha platform was properly tightened ? Would the incident have been avoided ? Would the many lives be left unharmed ? Would there be no
environmental impact ? Would there be no financial loss ? I believe we all have the answer in our hearts .
Separately , for typical maintenance work on a pressurised piping system , it is crucial to isolate the piping line intended for dismantling by ensuring that all upstream and downstream valves are closed or pressurised equipment shut down ( e . g . pump , compressor , etc .). Then the remaining stored or residual pressure in the isolated system is bled , followed by Zero Energy confirmation via pressure gauges . It is highly recommended to utilise proper Break Flange techniques while dismantling an existing flange joint , by leaving a small number of loosened bolts and nuts intact ( preferably four sets at least ). If trap pressure still exists in the piping line , the loosened bolts and nuts will hold the pipes via mechanical means .
Accident Avoided
Accident Occurred
Swiss Cheese Model
Equipment System People
With reference to the Swiss Cheese Model , all the basic barriers failed in the Piper Alpha incident .
● “ Equipment ” – Blind Flange not properly installed giving way for hydrocarbon release
● “ System ” – Work Permit not properly organised for operator to detect the risk
● “ People ” – Communication breakdown and no site verification done before pump restart
Note : There are many more factors in this incident , but for sharing purposes , the model is made simple .
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( Pipe Section to Remove )
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Common steps for pipe spool removal : a ) Shutdown Pump ( 1 ) b ) Close Valve ( 2 ) and ( 3 ) c ) Bleed the store pressure and check zero energy via a pressure gauge ( 4 ). d ) Dismantle flanges ( 5 ) and ( 6 ). |
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