Explosion in a Foundry
Coke oven gas was released from a pipeline during maintenance works. The pipeline was supplying the burners of the coke oven with coke oven gas. The original reason for the so-called gas-stop was some maintenance works on the water piping network. This procedure is carried out very seldom because it might damage the oven and takes about 10 h. Therefore, employees decided to do some works on gas pipe network and to execute other cleaning works in the meantime. In particularly, the gasometer used to store coke oven gas had been repaired the previous week. It was decided to perform safety checks just before the "gas stop". It was necessary to see if all the automatic controls were properly functioning.The explosion occurred when subcontractors were replacing a measuring diaphragm by a blind flange on the gas pipeline, which had not been properly inerted (or not inerted at all).The leak was estimated to release 1Nm3/s and was leaking for 5 to 10 minutes before the explosion. So 300 to 600 Nm3 (125 to 250 kg) of gas was released.The explosion caused the death of 3 subcontractors, 39 injured, among whose 13 seriously burned and material damage.
Event Date
October 22, 2002
Record Quality Indicator
Region / Country
Event Initiating System
Classification of the Physical Effects
Nature of the Consequences
Causes
Cause Comments
The immediate cause was a release from a gas line when opening a flange. The root cause was the absence of a safety culture. There were no written procedures to inert the gas line. On top of that, there was no coordination between the teams working at different duties on the same unit. Probably there were also design-related contributing causes, considering the difficulty to inert/isolate the lines.
Facility Information
Application Type
Application
Specific Application Supply Chain Stage
Components Involved
pipeline, coke oven, gasometer, metals processing
Storage/Process Medium
Location Type
Location description
Industrial Area
Operational Condition
Pre-event Summary
A "gas stop" of the coke oven had been decided approximately a month before to do some works on the water piping network. The "gas stop" was supposed to go on during 10 hours. So, workers in the coking plant decided to do some works on gas pipe network and some other cleaning works during this down time. This kind of "gas stop" is exceptional because it is very difficult to stop the coke oven. In fact, the oven is made of refractory bricks which can be irreversible destructed if their temperature goes under 600C. Lots of works were planned and it explains the big number of persons and particularly subcontractors present during the day of the accident. The gasometer (to store coke oven gas) had been repaired a week before the explosion and some tests had to be done on it. It was decided to do these tests just before the "gas stop"., to check if all the automatic controls were in place. The planned works for this day were: replace some valves on the water and gas piping network, cleaning a transport belt, cleaning of some other equipment and also replace a measuring diaphragm by a blind flange to be able to isolate a piece of the gas pipe. It is at this last work that the coke oven gas escaped. A subcontractor specialized on gas piping works was chosen to do this.
Consequences
Number of Injured Persons
1
Currency
Lessons Learned
Lessons Learned
1. Need for a safety culture.2. Need for written procedures to inert lines.3. Need for agreed working procedures that can be followed in the field.4. Need for a maintenance program for valves.5. Need for hazardous area classification to exclude ignition sources at places with risks for flammable gas leaks.
Event Nature
Emergency Action
The gas supply was stopped. The internal emergency plan was startedExternal and internal emergency teams were involved.
Release Type
Release Substance
Release Amount (kg)
250.00
Ignition Source
Ignition Delay (s)
600
Detonation
No
Deflagration
No
High Pressure Explosion
No
High Voltage Explosion
No
Source Category
References
References
From European database eMARS
https://emars.jrc.ec.europa.eu/en/eMARS/accident/view/0d09b5b2-6301-a18…
(accessed December 2020)
Event no 33030 of the French database ARIA (accessed December 2020)
https://www.aria.developpement-durable.gouv.fr/accident/23590/?lang
(accessed December 2020)