The learning objectives of this chapter are to understand how the arrangements
put in hand prior to entry into an enclosed or confined space continue and
develop when the space is occupied and to examine some of the emergency
procedures that may have to be put into effect
entry into the enclosed or confined space has been permitted because the
responsible officer has verified that the preperations has established in the
plan are all in place note that unless all necessary safety precautions can be
followed and enclosed or confined space should only be entered by personnel
wearing breathing apparatus appropriate personal protection against exposure to
flammable toxic or corrosive cargo vapors and if practicable a lifeline the
operation has now entered the next phase and many of the precautions will
continue to be required the continuing safe occupation of the enclosed or
confined space depends on those who have entered the space and the watchmen
remaining alert and watching for any changes in circumstances that may render
the space unsafe positive fresh air ventilation should continue during the
period that the space is occupied and during temporary breaks in the event of
a failure of the ventilation system any personnel in the space should leave
immediately
the atmosphere should be tested periodically whilst the space is
occupied both for oxygen content and the presence of flammable vapors personnel
should be instructed to leave the space if any deterioration of the conditions
is noted the atmosphere should be checked periodically from a remote
location normally the deck and the readings
recorded
the team inside should also have their personal monitors programmed to read the
atmosphere continuously preset alarm levels should trigger both an audible
and a visual alarm on the unit in the event of deterioration of the atmosphere
in the vicinity or in the event of a failure of the monitor some units also
have a vibration capability
if unforeseen difficulties or hazards develop the work in the space should be
stopped and the space evacuated so that the safety of the situation can be
reassessed permits should be withdrawn and only reissued with any appropriate
revisions after the situation has been reassessed and any additional controls
deemed necessary have been put in place
if the period of validity of the enclosed space entry permit or other
relevant permit to work has expired and not been replaced or renewed then work
should cease and the space should be evacuated this is a situation that
should not occur with a well-planned operation and closed monitoring of the
situation but it must be appreciated that such permits do expire and if
exceptional circumstances have led to the permit reaching the limits of its
validity then exiting the space is the only option possible
if any personnel in a space begin to feel sick or dizzy
or are in any other way adversely affected they should give the
pre-arranged signal to the watchman standing by the entrance and immediately
leave the space if the watchman is concerned by the signals or actions of
the team inside he should immediately raise the alarm
if someone inside the space is feeling unwell he may have difficulty in exiting
the space and be in need of assistance
should an emergency occur the general alarm should be sounded so that the
rescue team immediately assembles and backup is available the watch man should
remain by the access to the space and clearly and calmly appraised the
emergency team leader of the situation when he arrives on-site depending on the
assigned safety duties on the vessel the watchman may be in the part of the
rescue team to enter and undertake the rescue but he should not under any
circumstances into the space alone or before the rest of the rescue team has
arrived the rescue team must be well prepared
and trained regularly because time is critical in recovering casualties who
have been overcome and enclosed or confined spaces they should be
thoroughly familiar with the rescue equipment and effective in working and
communicating as a team
if air is being supplied through an airline to the person who is feeling
unwell a check should immediately be made for the air supplied is being
maintained at the correct pressure and is free from sources of contamination
the cause may be related to heat exhaustion but if the problem originates
with the air supply others being supplied from the same source may also
become affected once the casualty is reached the
checking of the air supply must be the first priority unless he is gravely
injured such as having sustained a broken back he should be removed from
the dangerous space as quickly as possible
if movement is not immediately possible then resuscitation and medical equipment
will need to be taken inside the space the medical team may have to wear
breathing apparatus themselves to treat the casualty
this ship was a 9000 695 deadweight tons chemical tanker at the time of the
incident she was engaged in tank cleaning following discharge of a cargo
of ethylene dichloride the center tanks was stainless steel and the wing tanks
had a zinc silicate coating the pump man and a sailor were running the machine
cleaning and the bosun was following behind with another sailor starting
ventilation fans as the washing finished and then ejecting the remaining washing
water from the after ends of the tanks the first two tanks were tested by the
chief officer but he then went to attend to planning for the next cargo leaving
the subsequent testing in the hands of the boat who had received training in
the use of testing equipment and was approved as an operator under the
vessels safety management system tank number four sent a port was tested and
21% oxygen was found no evidence of toxic gas was noted a green safe for
entry tack was fitted to the lid and the appropriate entry permit was filled out
although it was added to a folder of permits without the chief officers
verification signature being obtained at that time
the bosun entered the tank climbing down the access ladder while the Sailor
lowered the suction hose from the ejector pump through a cleaning hatch
above the sump he did not wear any breathing apparatus or carry an
emergency escape breathing device with him at the time the sea was calm and the
vessel had a considerable Stern trim and a slight list so quite a lot of water
was lying in the outboard after corner of the tank the bosun commenced removing
this water holding the section pipe at a slight angle to maintain the suction
after approximately two minutes and with around half of the water removed he got
a sudden blast of cargo vapor full in the face he immediately dropped the
ejector hose and ran towards the ladder catching his breath and with eyes
watering he climbed out of the tank more by feeling his way from rung to rung
than anything else the sailor on deck had seen the bosun running away and
already raised the alarm through his radio to the bridge the chief officer
had also heard the broadcast and was already halfway up the deck as the bosun
emerged through the hatch the bosun vomited over the side and then
sat down gradually recovering over the next 15 minutes or so the chief officer
tested the atmosphere in the tank for the record but the ventilation fan had
already stirred up the vapor to a noticeable level anyway it was found
that the cargo residue being of a greater density had settled beneath a
layer of water in the corner of the tank as the water was removed by the ejector
the product was exposed and the vapors were released the meter readings
obtained before entry were correct because the cargo residue was
effectively contained by the water and the air above had been successfully
purified by the ventilation fan the bosun was not aware of the risk of cargo
remaining and simply trusted the meter readings he did react when the
conditions changed but was lucky to escape from the tank without serious
injury