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Crisis Groups For Disaster Management
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Accident case study summaries
Fire during Toluene distillation

Facts in brief :
Chocked drained valves-hammering-breaking of the drain pipe – hot toluene spread in the work room – spark form wood fired boiler nearby – fire -10 workers died.

Causes :

1. Wrong method of de-choking.
2. Source of ignition nearby.
3. Condenser blocking.
4. Sudden opening of steam valve to raise temperature.

Remedial Measures :

1. De-choking device for drain –valve or appropriate method.
2. Safety distance of boiler etc. from flammable processes(at least 15m or see Petroleum Rules)
3. Periodical cleaning of column condense.
4. Slow operation of steam valves.
5. Temperature control to prevent overheating. Temperature alarm interlocked with heat source cut off device.

Phosphine Exposure

 

Facts in brief :
shoveling red phosphorous to make AIP/ZNP- Phosphine exposure and the worker died.

Causes :

1. Moist atmosphere while handling phosphorous can generate PH3 gas which has no colour. Its sp.gr. being 1.185, normally remains at working level and easily inhalable. Its TLV is 0.3 ppm and STEL 1 ppm. Its lowest published lethal concentration (LCL0) is 8 ppm. Therefore, it is highly toxic and affects CNS.

2. Worker had no respiratory protection.

3. No measurement and monitoring or sensor with alarm in working area.

Remedial Measures :

1. Moisture and water should be strictly avoided.
2. SBA or Airline respirator necessary.
3. Sensor with alarm set at 2 ppm.
4. No confined space. Full ventilation desirable.
5. Looking to its fire risk(AIT 40 to 600C), flameproof electric fitting and avoidance of spark.
6. Worker heaving blood lung disease should not be employed. Pre-employment medial examination can detect this.

 

Exothermic Reaction

Facts in brief :
Due to failure of cooling system, heat of exothermic reaction increased – tremendous pressure exploded the vessel – top cover with stirrer and reduction gear box crossed the Nationa Highway and fell into a factory on opposite side-bottom part of the reactor dashed into the land causing deep pit.

Causes :
1. Cooling failure. No alternate source.
2. No pressure/ temperature alarm.
3. Inadequate pressure relief device.
4. No interlocking to stop further heating.
5. No auto control.

Remedial Measures :
1. High pressure/ temperature alarm.
2. Adequate pressure relief device.
3. Rupture disc in addition to safety valve with safe discharge.
4. Cooling failure alarm and alternate cooling water/ pump     arrangement.
5. Interlocking of cooling failure with heat source cut of device.
6. Quenching device.
7. Alternate power supply.
8. Auto controls.
9. PRV for shell pressure and jacket pressure in case of jacketed     vessel.
10. Statutory testing of vessel and safety device.
11. Flame proof electric fitting if flammable material is used.
12. Trained worker and proper supervision.

Note :
Some of above remedial measures are also useful to prevent accidents due to jet dying machine, drum washer etc. in textile industry.

Ball Digester Blunder

Facts in brief :
Two workers were slipping under the ball digester in a paper mill- night time – to unload the disaster, a wrong switch was operated – digester started rotating – 20 ton hot mass with steam pressure of 70lb/inch2came out for about 15 minutes both the workers died.

Causes :

1. Mistake in identifying the correct switch for starting a drain/ discharge pump.
2. Switch to rotate the digester just aside and therefore, it was operated by mistake. This resulted as blunder.
3. Wrong habit of sleeping under the vessel or machine.
4. Contract workers with insufficient training.

Remedial Measures :

1. No worker should sleep under any machine or vessel in a work room.
2. Nearby switches should be properly marked for their proper identification. Switch with key preferable for sensitive operation.
3. Tagging indicating ‘not to start digester switch’ should have been displayed.
4. Proper training and supervision.

Pyrophoric Catalyst

Facts in brief :

Work of changing pyrophoric catalyst in a reactor at the depth of 15 feet – workers working in the atmosphere of 98% Nitrogen – A pipe of air line respirator detached. The worker was Suffocated – effort of pulling him out was made but he died.

Causes :

1. Poor fitting of lifeline of an air line respirator (air pipe).
2. Inadequate arrangement of communication and pooling worker out side incase of emergency.
3. Instead of using self breathing apparatus, air line respirators were used and there was entanglement of pipeline inside.

Remedial Measures :

1. Self breathing apparatus should be used in severe Oxygen deficiency.
2. Safety belt with lifeline should be attached and its free and should be held from outside in such a way that the worker feeling difficulty can be pulled out within shortest possible time.
3. Instead of using robe ladder, a portable wooden ladder should be used so that swinging, hanging and slipping can be avoided if this is not possible, sufficient training for using rope ladder should be given to the worker.
4. If airline respirators are to be used, their pipe connections should be checked for proper joint, no cut and no leakage.
5. Rehearsal of checkpoint of vessel entry permit before stating the work.
6. Work under constant supervision.

Chemical gas exposure as Scrubber Line Valve not opened

Facts in brief :

One reactor was used for pressure and vacuum reaction alternatively – Therefore scrubber line valve should be closed and the opened depending on the type of reaction required because of the continuity of reaction in the next shift and change in the process, the operator forget to open the scrubber line valve therefore Methyl Mercaptan gas evolved during the process could
not be escaped through the scrubber. While opening one valve to pour water in the reactor, the compressed marcaptan gas came out through that valve and worker died due to its heavy exposure.

Causes :

1. The same reactor work to be used for different type of reaction on the scrubber line valve was to be closed and opened manually frequently and more cautiously.
2. Error in not opening the scrubber line valve when it was necessary.
3. manual operation and no interlocking of scrubber line valve to keep it in correct position. Depending on type of process.

Remedial Measures :

1. No single reactor should be used for pressure, vacuum etc. so that scrubber line valve made frequent opening and closing.
2. Written SOP and batch sheet should be used to know before hand, that which valve requires which type operation and when.
3. Scrubber line valve should be interlocked with reactant charging valve so that it will automatically open at the time of charging the reactant and evolving of gas to be discharged from the reactor and through the scrubber.
4. When only one worker has to work in lonely place, a personal distress alarm should be attached with his body to indicate stoppage of its body movement in case of becoming unconscious and lying idle on the floor.

Ammonia Tanker Loading

Facts in brief :

While loading a road tanker through loading arm and liquid ammonia pipeline, the loading arm connection detached and the gas came out from the filled tanker as well as from the supplying
pipeline. The operator starting nearby tried to run away but fell from the platform and remained for few minutes in heavy concentration of ammonia. He died.

Causes :

1. Threads of coupler joint were worm out which were not checked and hence the joint was detached.
2. Worker has not worm respiratory protection.
3. There was no second ladder to run away from the loading platform.
4. There was no device of immediately stop the broken pipeline and the road tanker fill point in case of sudden failure.

Remedial Measures :

1. Thread gauge should be used regularly to check thread condition (pitch, sharpness and strength) of such type of sensitive joint.
2. In addition to thread joint. bolted connection or some locking device should be used to ensure no detachment of the connection.
3. With the breaking on the coupling, the two end should be auto closing device(e.g. Reliance jetty, Jamanagar).
4. Worker should wear SBA while standing near such connection and filling the road tanker.
5. Pipeline valve should be operated very slowly and gradually.
6. Worker should stand not in the direction of wind.
7. The loading platform should have exit ladder at least in to opposite directions.

Portable Electric Equipment

Facts in brief :

while using portable drill ,grinder ,lamp and other equipment ,due to short circuiting and electric shock ,many fetal accidents have been occurred.

Causes :

1. un-insulated open ,broken or worn out electric wire or loose connection.
2. No provision of use of ear thing conductor.
3. Only one ear thing resulting in to failure
4. No checking of earth pit resistance.
5 No ELCB or similar device.

Remedial Measures :

1. Portable electric wire \cord should be checked before use. There should be no tap joints or open insulation.
2. Loose electric wire should not lie on the floor or in water or under the leg of a metallic stool or ladder. The wire should not be rested on metal vessel , machine or any metallic parts. It should be tied or rested at height so as not at to come in the way.
3. Three pin top and plug should be used instead of inserting open wire into the plug.
4. Proper earthing and double earthing as per statutory requirement should be used.
5. ELCB (earth leakage circuit breaker) should be inserted into the circuit to avoid electric shock from leakage current.
6. Rubber or wooden mat should be used for standing. Shockproof electric gloves should be used.
7. Flameproof electric fitting should be used in flammable atmosphere.
8. Portable hand lamp should not be of more than 24 volts.

Dust Explosion in Dextrin plant

Facts in brief :
In a Dextrin (starch) making factory, explosion took place due to fine dust (powder) of starch and 19 workers died due to heavy fire and explosion.

Causes :
Flammable starch dust in air in explosive range and source of ignition available.

Remedial Measures :
1. Level of starch dusts should be measured and monitored to keep them below permissible limit (TLV 10mg/m3 for respiration purpose, LEL should be determined).
2. Electrical fitting in the plant should be flameproof.
3. Explosion relief device should be attached on dust (starch) generating machine/equipment.
4. In starch dust is in open atmosphere, source of ignition, friction, vibration etc. should be avoided. Non Metallic shoes should be used.

2-4 Dichlorophenol splashing from hose pipe

Facts in brief :
This chemical was being filled in a carboy with tight fitting hose inserted into its mouth without allowing air vent – old hose pipe ruptured due to pressure – Chemical sprayed on the body of the worker. He took bath under safety shower, yet died within 20 minutes.

Causes :

1. No provision of air vent while filling by liquid.
2. Worn out and weak hose pipe.
3. No PPE for body protection.

Remedial Measures :

1. Toxicity of the material must be known before its use.
2. Necessary PPE should be worn after going through the properties and precautions mentioned in the MSDS.
3. Safe air vent should be provided before starting to fill any vessel.
4. Hose pipe and connection should be checked while handling and toxic material.

Explosion during runaway type nitration reaction

Incident:
During nitration in reactor runaway reaction occurred and suddenly the pressure of reactor raised and explosion took place within few seconds in reactor. Manhole of reactor was opened due to high pressure. Nitric Acid, sulfuric Acid & Benzoic Acid were involved in reaction.

In this incident the mixtures of acids were sprayed in process plant, company ground and nearby company. The roof sheets of plant were broken due to explosion. It was sprayed up to about 200 – 300 meters in down wind direction

Cause of Accident:
As per information received from company officials the explosion was occurred due to runaway reaction during nitration from reactor of process plant.

Corrective Action
Lime was sprayed on the acidic mixture in whole the affected area in company & on the road also for neutralization. After that the road was washed out with water. Company people also sprayed lime on the acid mixture in their company ground & Process Plant.

Preventive Action
1. Process parameters to be followed strictly.
2. PRV & safety valve to be maintained in working condition with proper venting system.
3. Periodical maintenance & inspection should be done.
4. Employees should be trained in process safety.
5. Laboratory Study for knowledge relative to normal & abnormal known deviation in raw material, Process parameter

Fire and minor explosion in R & D oven

Incident:
Fire and minor explosion in R & D oven. The fire was minor but due to splash of flame and explosion 3 persons got major burn injury.

Cause of Accident:
It was suspected that temperature controllers might be not working properly so there may be possibility of increase of temperature to explosive limit. Another suspected cause might be solvent containing material was kept for drying and without removing solvent traces directly started heating.

Corrective Action:
The fire was extinguished using of CO2 Extinguisher

Preventive Action:
1. Auto controller equipment should be maintained in good working condition.
2. All instruments should be calibrated periodically by third party.
3. The material which contains solvent traces should be dry before starting heating.
4. Nitrogen blanketing in oven, if possible.
Bursting of Reaction vessel due to excess Pressure

Incident:
During reaction between ortho Nitro Chloro Benzen, Sulphonic Acid and Oleum suddenly pressure increased and manhole cover flown away breaking nut bolts and roof. Whatever material was inside was spread on surrounding area and nearby 2-3 companies. Manhole cover was not found. Nobody was injured.

Cause of Accident:
It was suspected that vessel might have puncture and cooling water entered into the materials which create exothermic reaction and pressure might have increased. Due to over pressurize of vessel, manhole and material flown away on near by area.

Corrective Action:
Acidic material was spread on surrounding area & near by 2 companies which was neutralized by soda ash and washed out.

Preventive Action
1. Regular inspection of the vessel. It should be periodically hydro tested by competent person.
2. Proper venting arrangement and it should be connected with scrubber.
3. SOP for emergency shut down.
4. Employees should be trained for abnormalities may be occurred during operation.
5. Knowledge of incompatible material used in the process.

Exposor to toxic gas during cleaning tanker

Incident:
One person (Cleaner) entered in the road tanker for washing and cleaning which was used to transport NaHS (Sodium Hydro Sulphide) was affected due to gas. Immediately Driver entered inside the tanker to rescue the cleaner without any safety precautions. Both were dead within few minutes.

Cause of Accident:
Without decontamination procedure and checking content of oxygen inside the tank, they were doing the cleaning job.

Corrective Action:
It was difficult to enter with SCBA. So with the use of trolley mounted BA set both persons were rescued and sent to hospital where they were declared dead by doctor.

Preventive Action:
1. Before washing any tanker containing chemicals should be decontaminated by authorized service station.
2. Before entering into the tank gas concentration and content of oxygen should be checked.
Driver should be trained by 3 days Drivers training course of safety transportation of hazardous goods by Govt. Authorized center.
Explosion in pipe connecting two E.O. receivers

Incident:
Two Ethylene Oxide receivers to process vessel were connected from the bottom. Explosion was occurred in the bottom pipe of receivers. One receiver’s bottom valve burst and Ethylene oxide was sprayed in first floor and ground floor. Another bottom valve was closed but due to explosion & fire it’s started leaking from main hole and bottom valve flange. Two persons were got minor injury who were sent to the hospital and given first aid treatment.

Cause of Accident
It is suspected that explosion may be occurred due to pressurization on Ethylene Oxide receiver. Which converted in to the explosion due to contact of Ethylene oxide vapors with spark from somewhere.

Corrective Action
Fire was controlled by using Foam, Portable DCP fire extinguishers and water for cooling.

Preventive Action
1. Company had no fire hydrant point at the backside of plant so, fire hydrants should be installed at key locations with foam facility.
2. Portable fire Extinguishers as per requirements should be installed.
3. They have stacked drums in large quantities in the congested locations. Housekeeping should be improved.
4. Employees should be given training for fire fighting.
Fire in chemical storage area due to centrifuge

Incident:
In whole plant area, vessels and other equipments were caught fire. The fire was started from the centrifuge. As there was no proper storage of chemicals. Many drums and carboys containing flammable liquids like Benzene, Methanol & Intermediates materials were kept in process area. When fire took place in centrifuge it spread in whole plant due these drums and carboys.

Cause of Accident:
The fire was broken out in solvent traces in centrifuge. It is suspected that it may be caused due to some spark from nearby area.

Corrective Action
:
Fire was controlled by using Foam, Portable DCP extinguishers, and water for cooling. Total 8 fire vehicles were used to control fire.

Preventive Action
1. Required fire fighting facilities should be provided at such type of area.
2. Portable fire Extinguishers as per requirements should be installed.
3. Employees should be trained for fire fighting.
4. Housekeeping should be improved.
5. Solvent storage should be done in proper way as per mandatory requirements.

 

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