Cockenzie steam drum failure

The Cockenzie steam drum failure of May 6 1966 [5] happened during the final, seventh cycle of hydraulic pressure testing before the steam drum would have been declared ready for service. It failed adjacent to one of the economizer nozzles, the transition pieces to the high-pressure pipes in operational service, would have led water from the underside of the drum to the boiler tubes (See Fig. 7.6.)... 

The Cockenzie steam drum after failure, with the failure site (inset). The dark tarnished area shows that the crack already existed during final heat-treatment, because the crack surface had discolored (public domain). 

The advantages of hydraulic proof pressure testing are best demonstrated by reference to the failure of a large steam separator drum at Cockenzie Power Station in East Lothian, Scotland, on May 6, 1966. (Separator drums are large, horizontal, cylindrical, thick-walled steel pressure vessels used to separate steam and water in coal-fired or nuclear power stations.)... 

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