Ammonia Gas Cylinders Explosion

 

This safety alert is issued following an incident involving two explosions of ammonia gas cylinders at an ammonia gas filling and bottling plant in state of Melaka on March 2011.The plant has been operating for more than 20 years. The ammonia stock from the suppliers will be stored first in the bulk storage tanks with a capacity of 500 and 900 tons waiting to be transferred or filled into the ammonia gas cylinders. The capacities of these cylinders are 60kg, 68kg and 500kg. Most of these cylinders were older than 20 years.

On the day of the incident at about 5:45pm, a gas cylinder filled with ammonia and stored in the horizontal position on the ground in two rows suddenly exploded. The first explosion caused the stored cylinders to roll away and scattered about into the surrounding area ( Figure 1 ). Others effects resulting from the explosion were :-

1. An ammonia cylinder flung off and landed on another factory compound that was situated just opposite and not far from the scene.
2. Part of the cylinder head that had exploded from another cylinder flew to an oil lubricant factory and hit one of the lubricating oil pipeline system and cause some minor damage to the pipe insulator.
3. One cylinder flung off and damaged the roof of surau that was adjacent to the mill office building.
4. One cylinder flung and landed onto the refilling station within the area of the plant.

At about 7.15 pm, an ammonia gas cylinder that was earlier thrown into the refilling station suddenly exploded. The second explosion caused severe damage to the refilling station roof and also one adjacent cylinder that had been hurled out, fell into the storeroom causing severe damage to the roof and ceiling of the storeroom. The exploded ammonia gas cylinder was found torn on the part of the shell.

Fortunately, there were no injuries and deaths in this incident. Rescue team arrived at the scene and stabilized the area of explosion.

Initial investigations found that the explosion might be caused by the increase of pressure (internal pressure) of ammonia gas in the cylinder that was stored outdoor and the presence of certain defects on the ammonia gas cylinders.

Action For Improvements

The safety measures or improvements that can be taken to prevent recurrence of the similar incident.

1. Fully comply with the requirements contained in the anhydrous ammonia SDS, especially during the bottling, storage, handling and transportation processes.
2. To carry out periodic inspection and testing of gas cylinders in accordance with recognized codes or standards.
3. Conducting a comprehensive maintenance schedule for ammonia gas cylinders.
4. Gas cylinders may be stored outdoors and on supports from the ground to prevent corrosion. Where extreme temperatures prevail, cylinders should be stored so that they are protected from the direct rays of the sun.
5. Full and empty cylinders should be stored separately and identified by signs to prevent confusion.
6. Gas cylinders should be stored in a well-ventilated area away from flames, sparks, or any sources of heat or ignition. Also keep cylinders away from any electrical circuit which can cause sparking action.
7. Gas cylinders should not be exposed to an open flame or to any temperature above 52°C.
8. Gas cylinders should not be,rolled,used as supports, or for any purpose other than for the storage and of gas.
9. Ammonia gas cylinders should always be stored or arranged in upright position and held firmly to prevent it from falling, overturning and being knocked over. Use appropriate cage and hand truck to lift or carry the cylinders. Do not roll, drag, pull or slide the cylinders.
10. Workers should be given training, written guidance and information on safe procedure and method of handling ammonia gas cylinders follows with close supervision by their supervisor.

Additional References:

1. Anhydrous Ammonia MSDS.
2. Department of Occupational Safety and Health Malaysia, Guidelines On The Control Of Chemicals Hazardous to Health
3. U.S. Occupational Safety and Health Administration, Occupational Safety and Health Guideline for n-Hexane
4. Canadian Centre for Occupational Health and Safety, Working Safely with Ammonia Gas
5. Virginia Commonwealth University,Office of Environmental,Health and Safety,Compressed Gas Cylinder Safety.