Introduction to Fire Safety Management

Introduction to Fire Safety Management
142
8.2.2 Hot 
works
Generally the term ‘hot work’ applies to the use of open 
fl ames, fi res and work involving the application of heat 
by means of tools or equipment.
More specifi 
cally hot work includes any works 
involving the use of naked fl ames, such as when welding 
or brazing, or when undertaking plumbing work with gas 
torches. Hot work also includes the use of grinders which 
create high temperature sparks and also includes the use 
of hot air guns for sealing materials such as fl ooring.
The use of naked fl ames and tools that apply heat, 
in themselves will not necessarily be the cause of fi re, 
but the inappropriate use of the equipment or lack of 
control of combustible materials, fl ammable vapours, 
etc. when undertaking hot work operations have been 
the start of many fi res within the construction and 
maintenance sector.
Sparks, for instance, falling on unprotected wood 
or behind panelling or onto wood shavings or dust can 
ignite the material. It has also been known that the heat 
generated by hot air guns when laying fl ooring mater-
ials can ignite combustible items upon which the fl ooring 
is being laid particularly as the heat generated in the 
process is then sealed in.
It is often the case that sparks of heat generated in 
such ways may go unnoticed for long periods of time 
and given the correct conditions, perhaps opening 
up sheeted areas, etc., will provide additional oxygen 
supplies to complete the fi re triangle. Fires can start in 
this way as long as 1–2 hours have elapsed after the 
works have been completed.
Open fi res such as bonfi res to burn site rubbish 
are to all intents and purposes banned in construction 
operations due to fi re risk; however there are a variety of 
different ways that naked fl ames can start a fi re.
Operations such as the laying of bitumen in fl at 
roofi ng operations requires a bitumen boiler which is 
powered by LPG and can pose a signifi cant risk if not 
managed effectively; this also falls under the title of hot 
work operations.
The use of bitumen or tar boilers can present a 
signifi cant risk. Such fi res are invariably due to:
➤
Poorly maintained equipment (thermostat faulty or 
poorly adjusted)
➤
Poor position of the boiler such as on the roof itself 
with no fi re resistant materials between it and the 
roof
➤
Poorly supervised units allowing the boiler to boil 
over or boil dry
➤
Attempting to move boilers while the burner is still 
alight
➤
Overfi lling of the boiler allowing the boiler to boil 
over
➤
Use of LPG cylinders without the appropriate safety 
features such as fl ashback arrestors.
The use of oxy-fuel equipment such as acetylene and 
propane are inevitably responsible for a number of fi res 
in construction and maintenance operations. Many 
of the key causes have already been discussed in this 
chapter such as poor maintenance, use in close proxim-
ity to combustibles, fl ammables, etc.
The additional risks that the use of such equipment 
brings arise from such issues as poor handling and 
storage arrangements for cylinders of acetylene.
Acetylene is an extremely fl ammable gas. It is different 
from other fl ammable gases because it is also unstable. 
Under certain conditions, it can decompose explosively 
into its constituent elements, carbon and hydrogen. 
This decomposition can be more readily brought about 
from mishandling, dropping, etc. of the cylinder causing 
damage to the internal mass. Uncontrolled leaks from the 
acetylene cylinder regulator or hoses can also have the 
same effect.
Additionally the contamination of oxygen supplies 
(cylinder, valve, regulator, hoses, etc.) by oil or grease 
also has the capability of causing an explosion.