Maintaining Process Equipment - Explosion

A major shutdown for planned maintenance was initiated which involved depressurizing the plant and flaring hydrocarbons. As part of shutdown work scopes, the main flare air blowers were taken offline leading to no positive pressure within the air annulus of the flare warm wet (FWW) and spare 1st stage flares. These two air assist flares were communicating through common air ducting and open dampers. A venturi effect (created by a low-pressure point at the spare 1st stage tip) drew hydrocarbon from the flare warm wet gas riser/pilots into the air annulus towards the spare flare. A flammable atmosphere was then created and ignited at the flare warm wet tip, leading to a deflagration (causing flare warm wet tip damage) followed by a detonation which caused the flare warm wet bellows to rupture.

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