Introduction to Health and Safety at Work

6.7.4 Work requiring a permit
The main types of permit and the work to be covered 
by each are identifi ed below. Appendix 6.3 illustrates 
the essential elements of a permit form with supporting 
notes on its operation.
General permit
The general permit should be used for work such as:
➤
alterations to or overhaul of plant or machinery where 
mechanical, toxic or electrical hazards may arise
➤
work on or near overhead crane tracks
➤
work on pipelines with hazardous contents
➤
repairs to railway tracks, tippers, conveyors
➤
work with asbestos-based materials
➤
work involving ionising radiation
➤
roof 
work
➤
excavations to avoid underground services.
Confi ned space permit
Confi ned spaces include chambers, tanks (sealed and 
open-top), vessels, furnaces, ducts, sewers, manholes, 
pits, fl ues, excavations, boilers, reactors and ovens.
Many fatal accidents have occurred where inadequate 
precautions were taken before and during work involv-
ing entry into confi ned spaces. The two main hazards 
Figure 6.8
Permit to work.

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Principles of control
91
are the potential presence of toxic or other dangerous 
substances and the absence of adequate oxygen. In 
addition, there may be mechanical hazards (entangle-
ment on agitators) ingress of fl uids, risk of engulfment in a 
free fl owing solid like grain or sugar, and raised tempera-
tures. The work to be carried out may itself be especially 
hazardous when done in a confi ned space, for example, 
cleaning using solvents, cutting/welding work. Should the 
person working in a confi ned space get into diffi culties for 
whatever reason, getting help in and getting the individual 
out may prove diffi cult and dangerous.
Stringent preparation, isolation, air testing and 
other precautions are therefore essential and experience 
shows that the use of a confi ned space entry permit is 
essential to confi rm that all the appropriate precautions 
have been taken.
The Confi ned Spaces Regulations 1997 are summar-
ized in Chapter 17. They detail the specifi c controls that 
are necessary when people enter confi ned spaces.