| |
|
-
REPORT CHARACTERISTICS:
DONOR: Office of the Chief Coroner
JURISDICTION: Ontario
REPORT TITLE: Verdict of Coroner's Jury
INDIVIDUAL PRESIDING: Dr. R. D. MacKinlay, Coroner
PLACE OF INQUIRY: Sarnia
DATE OF INQUIRY : 1984-07-16
INFORMATION ABOUT DECEASED:
NAME: John Douglas McLean
OCCUPATION: Maintenance
INDUSTRIAL SECTOR: Petrochemical
NAME: Kenneth James George
OCCUPATION: Maintenance
INDUSTRIAL SECTOR: Petrochemical
ACCIDENT INFORMATION:
DATE OF ACCIDENT : 1984-04-20
PLACE OF ACCIDENT: Polysar Ltd., Vidal Street, Sarnia
BRIEF CAUSE OF DEATH: Multiple injuries to lungs and other areas
of both
bodies.
BRIEF MANNER OF DEATH: Due to explosion of hydrogen cloud that
caused shock
wave injuries.
ACCIDENT DESCRIPTION:
These two employees of Polysar Corporation were engaged in the
start-up
of the Litol Unit after it had been shutdown for its six month
maintenance inspection. During the start-up, hydrogen gas was
gradually
built up to over 600 pounds per square inch in the system when
the
gasket sealing on an eighteen inch manway cover blew out allowed
several
kilograms of hydrogen to escape which resulted in an explosion,
killing
the two men and causing extensive damage.
RECOMMENDATIONS ISSUING FROM INQUIRY:
1. (a) That all durable type gasket material be tagged indicating
the date
received from the manufacturer and the gaskets themselves be
tagged
indicating date received.
(b) Quality control procedures should be made on all gaskets
prior to
use.
(c) In the petrochemical industry, bolt to bolt type gaskets
be adopted
as standard.
(d) That a manual be prepared that will be accessible to all
maintenance personnel outlining the correct gasket for a particular
flange.
(e) A written record be maintained when changes in type of gasket(s)
takes place with a reason for the change stipulated and with
the name of
the person who authorized the change.
2. That standard procedures for tightening flanges on high pressure
lines
and lines carrying toxic substances should be:
(a) testing of torque,
(b) in line air pressure gauges,
(c) regular maintenance on a time frequency basis.
3. Flange designs, incorporating radial restraint and capable
of retaining
gasket fragments under leakage conditions should be adopted
as this
would minimize the effects of gasket failure.
4. For start-ups, a standard operating procedure should be used
throughout
the petrochemical industry.
(a) Any deviation from this procedure as laid down by a manual
must
have written approval by the on-site foreman.
(b) Initiate a complete check-off list to ensure that all turn
around
maintenance work is completed and that the unit is ready for
service
before starting up.
(c) Radio communication is necessary at all times and especially
during
start-up and shutdown.
5. The rationale for enclosing high pressure compressors, especially
in
areas of highly volatile gases, should be reviewed with the
intent of
removing the enclosure.
6. The location of control rooms should be reviewed so that
the buildings
and contents will not be seriously affected due to operative
unit
explosions.
7. Standard operating procedures should be updated each time
that changes
are made in the system and whenever there is equipment changes
to ensure
that these changes have been communicated to all personnel involved.
8. Shut-off valves should be in place between one piece of equipment
and
another and located in such a way that no flanged connection
should
intervene between the shut-off valves and the equipment which
is the
potential source of leakage.
COMMENTS ON RECOMMENDATIONS BY CORONER:
1. (a) The jury were told that the type of gasket used, deteriorated
over
a period of time.
(b) Self-explanatory.
(c) The jury learned that the type of gasket used was not always
centred properly and were told that if the gasket was bolt to
bolt, it
would eliminate the problem.
(d) Self-explanatory.
(e) Self-explanatory.
2. The jury learned that the manway cover may not have been
tightened
sufficiently because pneumatic wrenches were used to tighten
the bolts
on the manway cover.
3. The jury learned that the flanges on the manway opening were
flat with
no inset for the gasket.
4. The jury learned that the operators during start-up follow
a routine
they had developed from experience and nothing was specifically
written
for a checklist.
5. The jury learned that the Litol Unit was enclosed on two
sides and a
roof and this increased the concentration of the hydrogen gas
and
increased the force of the explosion.
6. The control room for the Litol Unit was badly damaged by
the explosion
because it was not protected by an earthen barrier or some other
protection.
7. Self-explanatory.
8. The jury learned that a flange damaged by the explosion leaked
a
volatile liquid for seven hours because there was not a shut-off
vlave
between the flange and the supply.
|
|
|