FPASA BULLETIN GF 01
HOT WORK
Welding operations have been the cause of numerous serious fires over the years.
One of the largest industrial fires on record involving a single building occurred in the
General Motors plant at Livonia, Michigan, USA in 1953, the cause being attributed to Oxyacetylene cutting in the presence of highly flammable material. The fire burnt out more
than 14 ha of industrial plant.
In South Africa a warehouse containing synthetic fibres was burnt out when sparks from
welding operations being carried out on a metal fire door separating the raw materials
store from the factory ignited the material nearby.
Many serious accidents have been caused by cutting or welding being performed on
closed drums, tanks or other receptacles containing flammable vapours. A most unusual
accident is on record concerning the explosion of a drum which was known to be entirely
gas free, having been used to carry water for some time. Investigation revealed that the
drum was being used as a stand during welding operations and when the operator first
opened the acetylene valve sufficient acetylene entered the drum through the open bung
hole to provide an explosive concentration which ignited when the torch was lit. Another
case is on record of a welder standing on an empty petrol drum on the sixth floor of a
building under construction. The sparks from the torch fell into the drum causing it to
explode, hurling the operator to his death.
It has been argued that fires caused through welding operations receive undue publicity
due to the fact that they are invariably known causes as against most other large loss fires
that occur the causes of which are generally listed as undetermined. Whilst this may be
the case it must also be obvious that such fires are without doubt the result of carelessness
or neglect.
Contributory Factors
A study of reports received over the years show that the following factors contributed
towards fires caused by cutting or welding:
1.
Contractors who are unfamiliar with the premises and hazards which may exist
often do not exercise the same degree of caution as would plant personnel.
2.
Welding visors or goggles prevent the operator from seeing where sparks may fall.
3.
Failure to remove or cover combustible goods in the vicinity of welding or cutting
operations.
4.
Failure to check for combustible materials on the reverse side of the object being
welded. (A large ocean liner was burnt out and capsized when welding being
carried out on a steel bulkhead ignited kapok lifebelts in an adjoining cabin).
5.
The absence of fire-fighting equipment in the vicinity of the welding operations.
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Precautionary Measures
Every factory should have a person designated as being responsible for ensuring that
hazardous activities of this nature are carried out under strict supervision. This should
include a suitable hot work permit system. The following general precautions should be
observed:
1.
The welding appliance should not be removed from the workshop area to the other
parts of the factory without the permission of the designated official. This official
should ensure that precautionary measures are observed.
2.
The area where hot work is to be carried out should be inspected.
3.
All combustible material in the vicinity is either removed, damped down or suitably
protected. A check should be carried out for any openings or cracks below the
working area which may cause sparks to ignite materials at lower levels.
4.
Outside contractors should be given strict instructions as to the procedures to be
adopted and particularly hazardous areas should be pointed out to them.
5.
Fire extinguishers and hose-reels should be provided near the site of welding or
cutting operations and operators should be experienced in the handling of such
equipment.
6.
When welding or cutting operations are carried out in particularly hazardous areas it
is advisable to have a person standing by with a fire extinguishers.
7.
A small fire extinguisher, possibly of the dry powder type, should be fitted to the
welding trolley itself.
8.
Leaking tubing, badly fitting valves and regulators and loose connections are all
sources of danger and the cause of many fires. Regular maintenance of equipment
is essential.
9.
Empty drums which have contained flammable liquids should not be stored in the
vicinity of welding or cutting operations.
10.
Empty containers which have held flammable liquids should be thoroughly
degassed, preferably by the application of steam, if they are to be welded or cut.
11.
Buildings in which welding or cutting operations are carried out should be well
ventilated in order that flammable or explosive gases and vapours may not
accumulate.
Maintenance of Welding Equipment
All welding equipment should be kept clean and in good working order and should be
regularly inspected. Rubber hoses should be red for acetylene and black for oxygen and
should be checked for cuts, cracks, burns and worn parts. Copper alloys of high copper
content react with acetylene to form an explosive compound (cuprous acetylide), and
tubing of these metals should not, therefore, be used for acetylene.
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Hot Work Permit
It is recommended that no cutting, welding or other hot work be carried out on factory
premises unless the operator has received a clearance in the form of a certificate which
must be signed by the responsible official. A suggested form of such a document is given
below.
The Hot-work Permit shown below is available from the FPA(SA) in English or
Afrikaans.
HOT WORK PERMIT*
Date………………………………………………
Permission is granted to
……………………………………………………………………………….
to use ………………………………………… in the …………………………………(exact
location)
between ……………………..am and ………………………..am
…………………….pm and …………………………pm
The above location has been examined. A man will be standing by with an extinguisher/
hose reel while the operation is in progress.
There are no combustible liquids, vapours,
gases or dusts.
He and the operatives have had the nearest fire
alarm/telephone pointed out to them and have
All combustible material has either been
been told what to do in the event of a fire
removed or suitable protected against
heat and sparks.
Signature of person issuing permit and position held
…………………………………………………
Work area and all adjacent areas to which sparks and heat might have spread were thoroughly
inspected on completion of the operation, and thirty minutes later no smouldering fires were
discovered.
Signature of person responsible for the work
………………………………………………………….
(After signing return permit to the person who issued it.)
*Applicable to all operations involving flame, hot air or arc welding and cutting equipment,
brazing and soldering equipment, blowlamps, bitumen boilers and other equipment
producing
Published by:
heat or having naked flames.
Fire Protection Association of Southern Africa
(Incorporated Association not for Gain)
(Reg.No. 73/00022/08)
P O Box 15467
Impala Park
1472
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