The safe isolation of plant and equipment (HSG253) - Health and ...

Health and Safety
Executive
120 As a general rule you should not use SBB as a final isolation method
for work on live plant containing hazardous substances, but there may be
circumstances where the use of SBB is justified. SBB should be used only where
risk assessment has shown it to be acceptable.
Selection of ‘ALARP’ isolation method
121 The flowchart at Figure 5 outlines the selection of an isolation method and
risk reduction measures for an isolation scheme. The ‘ideal’ path is highlighted in
yellow, but it is recognised that it will not always be possible to follow this route.
The box shaded in grey relates to the use of ‘variations’ (see paragraphs 128-141).
122 After establishing your ‘baseline’ isolation standard, you will need to complete
your risk assessment to ensure that risks are ALARP. Important aspects to consider
include:
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storage conditions (eg temperature);
additional risk reduction measures (see paragraphs 125-127);
whether use of a ‘variation’ is appropriate, eg for short term isolations (see
paragraphs 128-141);
11 personal injury considerations, eg manual handling, exposure to substances
which may be hazardous to health12 etc; and
environmental considerations (eco-toxicity).
123 Your final considerations should be whether risk levels have been reduced to
‘ALARP’ and whether the level of risk associated with the proposed isolation is
tolerable (see paragraph 16) – if not, then the work should not go ahead. No
individual step should create an intolerable risk for those carrying out the work.
124 The risk associated with some proposed isolations will be such that the
selection tool in Appendix 6 indicates the need for further consideration before you
proceed. You may decide:
■ that risk can be reduced to acceptable levels (ALARP) via risk reduction
measures;
■ that the isolation envelope should be extended; or
■ that these isolations should not be carried out on live plant.
Risk reduction measures
125 Consider measures such as (but not restricted to):
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reducing pressure and/or temperature;
reducing inventory;
detailed planning of the work:
– to minimise the duration of exposure to broken containment;
– to reduce the duration of the isolation; and
– to ensure that the correct type and quantity of PPE is immediately available;
restricting incompatible or non-essential work nearby;
restricting access around the worksite by barriers;
reducing the number of people working on the plant;
monitoring the isolation more frequently;
having an operator in attendance throughout the isolation; and/or
increasing supervision.
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