Safety talk

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• Safety talk
• Confined space incidents

A.K.Singh, B.Sc(Chem. Hons), B.E.,DIS,
MIIRSM(UK), Chief Manager (FS), Indian Oil
Corporation Ltd, Mathura Refinery, India,
Email singhak_at_iocl.co.in
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Sometimes it seems that vessels are more
dangerous empty than full.

• Case 1
• Contractors, unfamiliar with a company's rules,
  have often entered vessels without authority. For
  example, a contractor's foreman was found inside
  a tank which was disconnected and open, ready for
  entry, but not yet tested. He had been asked to
  estimate the cost of cleaning the tank. The
  foreman said that he did not realize that a
  permit was needed just for inspection. He had
  been given a copy of the plant rules but had not
  read them.
• If vessels are open, but entry is not yet
  authorized, the manhole should be covered by a
  barrier. One should not rely on contractors'
  reading rules.  Rules to be explained to  them.

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Source What Went Wrong? - Case history of
Process Plant Disasters by Trevor A. Kletz.
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Case 2 Two men went into a reactor to carry out
a dye-penetrate test on a new weld using
trichloroethylene. Because the weld was 8 m long
the solvent was soon used up, and the man who
was on duty at the entrance was asked to go for
some more. He was away for 10 minutes. When he
returned the two men inside the reactor had
collapsed. Fortunately they were rescued and
soon recovered. The amount of solvent that can be
taken into a vessel for dye penetrate testing or
other purposes should be limited so that
evaporation of the complete amount will not
bring the concentration above the TLV, making
allowance for the air flow if the vessel is
force-ventilated. Stand by workers should not
leave a vessel when others are inside
it. Source What Went Wrong? - Case history
of Process Plant Disasters by Trevor A. Kletz.
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Case 3 A second-hand dual compartment road
tanker was purchased for internal use within the
factory. It was to be used as a single
compartment tanker, so a welder was given the job
of burning out the internal wall that separated
the two compartments. As soon as he started
burning out the separating wall, a fire broke
out. The welder jumped back and escaped through
the manhole before the inside of the tanker was
engulfed in flames. It transpired that there
were two dished-end dividing walls built nose to
nose, and a solid wax had built up between the
two walls through a leak over the intervening
years during its use to transport heavy fuel oil.
This was not apparent after checking and
inspection prior to the modification work that
was to be carried out. There are always hidden
problems in confined entry that must be
identified. Source Loss Prevention Bulletin
Issue 158 April, 2001.
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• Case 4
• A tank had to be entered for inspection. It had
  contained only water and was not connected to any
  other equipment so the usual tests were not
  carried out. Three men went into the tank and
  were overcome. Two recovered but one died. The
  atmosphere inside the tank was tested afterwards
  and found to be deficient in oxygen. It is
  probable that rust formation used up some of the
  oxygen.
• Never take short cuts in entering a vessel.
  Follow the rules.
• Source
• What Went Wrong? - Case history of Process Plant
  Disasters by Trevor A. Kletz.

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Case 5 (a) A contractor entered the combustion
chamber of an inert gas plant watched by two
standby men but without waiting for the breathing
apparatus to arrive. While he was climbing out of
the chamber he lost consciousness halfway up. His
body was caught between the ladder and the
chamber wall. The standby men could not pull him
out with the lifeline to which he was attached.
So one of the standby men climbed in to try to
free him, without breathing apparatus or a
lifeline. The standby man also lost
consciousness. The contractor was finally pulled
free and recovered. The standby man was rescued
by the fire service but by this time he was dead.
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Case 5(b) In another incident, three men were
required to inspect the ballast tanks on a barge
tied up at an isolated wharf 20 km from the
plant. No tests were carried out. One tank was
inspected without incident. But on entering the
second tank, the first man collapsed at the
foot of the ladder. The second man entered to
rescue him and also collapsed. The third man
called for assistance. Helpers who were asked to
assist in recovering the two men were partly
overcome themselves.
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Representatives of the safety department 20 km
away set out with breathing apparatus. One man
died before he could be rescued. Tests on other
tanks showed oxygen contents as low as 5. It is
believed that rust formation had used up the
oxygen. Lesson on behavioral safety If we see
another person overcome inside a vessel, there is
a very strong natural impulse to rush in and
rescue him, even though no breathing apparatus is
available. Misguided bravery of this sort can
mean that other people have to rescue two people
instead of one.
Source What Went Wrong? - Case history of
Process Plant Disasters by Trevor A. Kletz.
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Case 6 A welder complained that a reactor which
had been cleaned and purged still smelt strongly
of solvent. The reactor was checked and it was
found that this was indeed the case, so it was
washed out and re-purged a second time. When the
welder went back to carry out the work inside the
reactor, he complained yet again that it still
smelt of solvent. After intensive investigation
it was found that the stirrer inside the vessel
was hollow and that a hole had been drilled into
it to prevent hydraulic pressure build up.
Solvent had accumulated in the hollow shaft of
the stirrer during the course of time.
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Although the general atmosphere inside the
reactor immediately after the washing and purging
was found to be clear, by the time the welder
came to do his work ,solvent had vaporized to
create a dangerous atmosphere inside the
reactor. There are often hidden places where
substances can hide. Always be critical in the
examination of a vessel and check all possible
hiding places. Source Loss Prevention
Bulletin Issue 158 April, 2001.
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Case 7 In the middle of a night shift in 1994 a
well-trained, recently-appointed and particularly
conscientious process operator decided to clear a
blockage in the outlet chute of a centrifuge. The
centrifuge and the product hopper were nitrogen
inerted. He must have dropped the spade he was
using into the product hopper and in order to
retrieve it he opened the hopper man way, put on
a canister respirator (presumably because of the
solvent vapour), ignored all vessel entry permit
procedures, and entered the hopper. He was
discovered a few minutes later, already dead,
asphyxiated by the nitrogen.
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Canister respirators are of no use in a nitrogen
atmosphere and the operator should have known
this. He should also have known that entry into a
confined space must be carried out only according
to the procedure. Emphasising all aspects of
vessel entry to all concerned on a regular basis
is very important. Source Loss Prevention
Bulletin Issue 158 April, 2001.