Explosion and Fire in Chemical Plant
The incident occurred in the hydrogenation Unit of a non-further specified chemical plant. Before the occurring of the event, a growing leak had been discovered in the vicinity of a circulation pump. The pump was switched off and a routine tightening operation of the stuffing box packing was executed. During the switching on again of the circulation pump, an abrupt depressurization via the pump took place. This was due to the fact that double gate valve on the pump's suction side was open, while the valve of the intermediate pressure reducer was closed. This caused the circulation pump to be exposed to the full system pressure of ca. 300 bar. The pressure bushing, the stuffing box rings and other associated components were driven out by this pressure.
Event Date
July 26, 1997
Record Quality Indicator
Region / Country
Event Initiating System
Classification of the Physical Effects
Nature of the Consequences
Causes
Cause Comments
Immediate cause was the re-start of the operation with the wrong set of valves parameters.Root or contributing cause was the lack of training/experience of the workers involvedAlthough not mentioned by the sources, a root or contributing cause was very probably the absence or inadequacy of operative procedures for the specific action executed. One could also ask if an automatic control system could not avoid the wrong choice of valves control.
Facility Information
Application Type
Application
Specific Application Supply Chain Stage
Components Involved
high pressure hydrogenation reactor, circulation pump, double gate valve
Storage/Process Medium
Location Type
Location description
Industrial Area
Operational Condition
Pre-event Summary
The accidents occurred after maintenance works which had caused to switch off the recirculation pump. The hydrogenation unit treated p-tert-butylcyclohexanol ( (CH3)3CC6H10OH) and p-tert-butylphenol ((CH3)3CC6H4OH).
Consequences
Number of Injured Persons
1
Environmental Damage
0
Property Loss (onsite)
Y
Property Loss (offsite)
N
Lessons Learned
Lessons Learned
The following actions were required:a)Supplementary training and instruction of the personnel on the topic "Tightening of stuffing box packing ", with a particular focus on the lessons learned from this accident. b)Instruction on hazards of working with pressurized equipment. c)Safety-related conferences. d)For a certain time, a person in charge will inspect the accuracy of the tightening operation carried out by the personnel. e)Afterwards, random inspections of the operation will be carried out by a person in charge.
Event Nature
Emergency Action
The circuit breakers of the hydrogen feed valves and the pump valves were actuated. The on-site emergency response service was immediately alerted and extinguished the fire.
Release Type
Release Substance
Hydrogen Release Concentration (%)
100.00
Release Pressure (bar)
300.00
Ignition Source
Detonation
No
Deflagration
No
High Pressure Explosion
No
High Voltage Explosion
No
Flame Type
Source Category
References
References
Event description in European database eMARS
https://emars.jrc.ec.europa.eu/en/emars/accident/view/e0bda8c2-77e3-ba7…
(accessed September 2020)
Event description in French database ARIA
https://www.aria.developpement-durable.gouv.fr/accident/14779/
(accessed September 2020)