Friday, 17 February 2012

Rope Access - Confined Spaces - Silo Cleaning

What is a Confined Space?

It can be any space of an enclosed nature where there is a risk of death or serious injury from hazardous substances or dangerous conditions.....this can be from lack of oxygen and even too much oxygen that can be combustable, LEL's such as methane and hydrogen sulphide are to name a few which should be monitored, prior and during entry.

Some confined spaces are fairly easy to identify, e.g. enclosures with limited openings:

* Storage tanks;
* Silos;
* Reaction vessels;
* Enclosed drains;
* Sewers.

Others may be less obvious, but can be equally dangerous, for example:

* Open-topped chambers;
* Vats;
* Combustion chambers in furnaces etc;
* Ductwork;
* Unventilated or poorly ventilated rooms or shafts.

It is not possible to provide a comprehensive list of confined spaces. Some places may become confined spaces when work is carried out, or during their construction, fabrication or subsequent modification.

What are the dangers from confined spaces?

Dangers can arise in confined spaces because of:

A lack of oxygen;This can occur:
  • where there is a reaction between some soils and the oxygen in the atmosphere;
  • following the action of ground water on chalk and limestone which can produce carbon dioxide and displace normal air;
  • in ships' holds, freight containers, lorries, etc., as a result of the cargo reacting with oxygen inside the space;
  • inside steel tanks and vessels when rust forms.
  • Poisonous gas, fume or vapour.
These can:
build-up in sewers and manholes and in pits connected to the system;
enter tanks or vessels from connecting pipes;
leak into trenches and pits in contaminated land, such as old refuse tips and old gas works.
Liquids and solids which can suddenly fill the space, or release gases into it, when disturbed. Free flowing solids such as grain can also partially solidify or 'bridge' in silos causing blockages which can collapse unexpectedly.
Fire and explosions (e.g. from flammable vapours, excess oxygen, etc.).
Residues left in tanks, vessels, etc., or remaining on internal surfaces which can give off gas, fume or vapour.
Dust may be present in high concentrations, e.g. in flour silos.
Hot conditions leading to a dangerous increase in body temperature.

Some of the above conditions may already be present in the confined space, however, some may arise through the work being carried out, or because of ineffective isolation of plant nearby, e.g. leakage from a pipe connected to the confined space. The enclosure and working space may increase other dangers arising through the work being carried out, for example:

  • Machinery being used may require special precautions, such as provision of dust extraction for a portable grinder, or special precautions against electric shock;
  • Gas, fume or vapour can arise from welding, or by use of volatile and often flammable solvents, adhesives, etc.;
  • If access to the space is through a restricted entrance, such as manhole, escape or rescue in an emergency will be more rescue procedures must be put in place prior to commencement of the works. 

What the law says:
You must carry out a suitable and sufficient assessment of the risks for all work activities for the purpose of deciding what measures are necessary for safety
(The Management of Health and Safety at Work Regulations 1999, Regulation 3).

For work in confined spaces this means identifying the hazards present, assessing the risks and determining what precautions to take. In most cases the assessment will include consideration of:

* The task;
* The working environment;
* Working materials and tools;
* The suitability of those carrying out the task;
* Arrangements for emergency rescue.

All staff entering confined spaces are subject to specific training and should be competent to manage the risk.......confined space entry, egress and rescue......and of course .....all staff should be trained in the correct use of.... and issued with the correct PPE under PUWER 1998.

If your Organisation requires any of our professional services, please dont hesitate to contact the team.