Disaster Area

Welcome to ” The Disaster Area”

I know compressor operators bang on about cylinders being in test but as you will see, there is a good reason for it.

INCIDENT NEWSFLASH “Gas Bottle Explosion”
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Summary Of Incident A gas bottle exploded in a lifeboat of a vessel during the process of charging it up from the Breathing Apparatus Air Compressor.The Master of the 8 years-old vessel was in proximity of the lifeboat and he was very seriously wounded. The bottle was quite old with different numbers/dates.The photographs below speak for themselves. Unfortunately one person was injured – imagine the results if this happened on the deck area with more people around.

Lessons Learned
(1) The incident related to Life Saving Equipment, which indicated the lack of inspections and maintenance programs.
(2) Ensure air cylinders or gas bottles are all in good condition. Guidelines are:Visual inspections every 2.5 years and pass hydro-test requirements every 5 years.
(3) Cylinder(s) in poor condition should not be moved or depressurized and should be roped off and warning sign(s) clearly displayed.

tank_explosion

The standard American DOT 3AL 3000 aluminum scuba tank manufactured by the Luxfer and Catalina companies, represents an amazing piece of metallurgical technology. The single piece seamless construction manufacturing technique, plus subsequent heat treatment results in a structure containing 20 times more strength than the original aluminium billet from which it was made. Rough handling, miss-use, corrosion and many other factors can critically effect the strength and integrity its construction. The end result is an explosion, that usually occurs during refilling, killing the compressor operator and destroying the dive shop.

cylinderbangFurther opportunity for death and destruction occurs during scuba tank inspection, when untrained technicians try to remove the pillar valve without testing that the tank is truly un-pressurized. In 2003, a dive instructor working at Koh Tao, Thailand suffered critical injury when a scuba tank pillar valve plus the removal clamp was jettisoned through his leg during a servicing action; the aluminium tank went through a few concrete walls off into the jungle. A well-trained-medic saved the dive instructors life.

Even for those Dive Operators attempting an visual inspection, few realize that an aluminum tank is susceptible to Sustained Load Cracking or SLC cracks in the neck area or carry out effective pillar valve thread inspections or gauging, or understand what ‘Eddy Current’ NDT testing is.

Cylinder CorrosionFurther confusion exists in the scuba industry, in that the hydrostatic test is somehow believed to be the usual way a dodgy scuba tank is identified and removed from service. The paradox is that scuba tanks rarely fail hydrostatic test and It is the Visual Inspection where most scuba tanks are identified as having critical defects and condemned or otherwise removed from service.

Steel tanks are also not without their own problems as anyone who has been near the sea with ferrous materials will testify. If there is one truth in the world it is ‘that rust never sleeps’ A flooded steel scuba tank lying on its side can exhibit corrosion accelerated by the high pressure of air in the tank, that can lead to critical weakening of the cylinder wall sufficient to cause an explosion within a few months.

 

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