Explosion in battery locker - CASE STUDY

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VESSEL TYPE:          Passenger
TITLE:                Explosion in Battery Locker
CATEGORY:             Personal Injury/Illness


The vessel involved in this incident was a purpose-designed sail training vessel built
in 1991. The vessel carried a substantial bank of lead acid batteries to power
emergency systems, radios and fire detection systems. The batteries were housed in
a locker on the port side of the main deck below the wheelhouse.

In addition to a permanent crew the vessel carried 31 students who, in addition to
pursuing academic studies, assisted in the sailing and maintenance of the vessel. On
the morning of the incident a party of students had been assigned the task of scaling
and painting the port side of the deck house. During the work an explosion occurred in
the battery locker. The blast threw one student overboard. Despite an extensive air
and sea search he was never recovered.


The student who died had been removing rust accumulations from around the battery
locker door with a rotary grinding machine. The battery locker door was secured by four
lugs and wing nuts. In order to grind off rust around the lugs the student loosened the wing
nuts and lifted them clear of the lugs. Sparks from the grinding machine entered the locker
and ignited an accumulation of hydrogen gas causing the explosion.

The battery locker door was marked with the word 'batteries' in large red letters. Signs
were fitted inside the locker to alert personnel to the presence of corrosive acid and the
dangers of corrosive acid burns. There were no external warning signs prohibiting naked
lights and smoking, nor was there any warning of the explosive risk.

Subsequent investigations revealed that the locker's ventilation arrangements consisted of a single 20
mm diameter vent pipe which made no provisions for through ventilation. This was inadequate to
dissipate the quantity of hydrogen gas given off at high charge rates.


Unsafe wing practices.

Issue Date: 01/01/02                                                             Case No. 26355

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