ARE YOU MONITORING SUPPORTS FOR THEIR INTEGRITY? ARE YOU PROPERLY CONGURING ALARMS?

In a refinery, an alarm in the control room informed the operators of a fire in the distilling unit. The unit’s emergency shutdown procedure was initiated from the control room. The internal fire-fighting resources were initiated at to extinguish the fire and cool down certain installations in addition to the fixed installations at the site. No injuries were reported on or off the site. The distillation unit was partially destroyed over an area measuring 50 m x 50 m, and flaring episodes were required.

A petrol leak was discovered on a 3” diameter pressure testing pipe of a flowmeter on a hollow tubular support. The operator had visually noted corrosion on the support already 3 years earlier. Replacement of the support was planned to take place during the regulatory shut-down period but was not performed. The ignition source was not precisely identified. Before the fire started, an alarm corresponding to the 20% lower explosive limit had been triggered 6 times, without the operators noticing. As some of the units had still been shut down, the alarms dedicated to the unit in operation were filtered. This filtering arrangement masked the display of the fire and gas alarms and only displayed those pertaining to the unit’s processes that had been restarted. The flashing light visible in the control room was considered a “process” alarm, knowing that such signals are not explicitly dedicated to fire and gas alarms.

Source: Aria database