Hydrogen fire from a piping

The incident occurred at the hydrocracker unit, which was being shut down for maintenance and the reactor was in a hydrogen purge cycle. A hydrogen gas line failed at a weld. The line was at 3000 psi (approx. 200 bar), resulting in a high-pressure hydrogen fire.
(1) The fire impinged on the calcium silicate insulation of the skirt of the hydrocracker reactor.
(2) The skirt failed causing the fall of the reactor.
(3) The falling reactor damaged air coolers and other process equipment, greatly increasing the size of the loss.
The initial hydrogen leak is believed to have resulted from the failure of an elbow to reducer weld in the hydrogen preheat exchanger by-pass line.

The INITIATING cause was the failure of a pipe welding.

This caused a domino effect with an escalation of the risks and the damages.
This suggests a incorrect design risk assessment as ROOT CAUSE. In the course of the evolution of the events, also shortcoming of the management of he emergency procedures became evident.

2-inch pipeline, protective steel skirt of a reactor, reactor ,nearby equipment

At the time of the event, the hydrocracker unit was in the process of being shut down for maintenance. The reactor was in a hydrogen purge cycle.

source MARSH reports a total financial damage of $90 Million (currently $200 Million).
Only ICHEME report fatalities.

(general, related to the management of emergency, not technical, related to the improvement of the reduction of the technical risk)
(1) Flame Resistant Clothing: a flame resistant clothing policy at all the refineries belonging to the own. Flame resistant clothing will be provided to and worn by all employees working in designated mandatory areas of the refineries.
Exception: employees merely passing through a mandatory area, not performing a task that could result in contact with a flash fire, or performing a task in a shutdown processing area that could not result in contact with a flash fire).
Mandatory areas: Hydro-processing, Cracking, Distillation and Reforming, Cat/Wax, Blending and Shipping and Utility Divisions.
(2) Turn Out Gear: to have available and require the use of turnout gear, by any operators who are requested by the incident commander to perform an operating function in the hot zone during a fire. (Hot zone is an area inside the perimeter established by the incident commander, where the risk of burn injuries to exposed skin could occur by flame contact or radiant heat).
(3) To reinforce owner’s policy as to operators' duties and responsibilities during the post-incipient stage of a fire. This includes outlining the general scope of operators' duties during an emergency; the use of flame resistant clothing and turnout gear during such emergencies; and that non-fire brigade operations personnel are not to enter the hot zone during a fire unless and until the incident commander so requests and turn out gear is provided and donned.
(4) To communicate this policy to all affected employees, in the form of a Refinery Instruction.