9.3 Confined Spaces: The 2010 ICOP, Hazardous Atmospheres, Roles, Permits and Rescue

Why confined spaces kill

Many confined space deaths follow the same pattern. One worker is overcome by gas or lack of oxygen, and co-workers who go in to help without breathing apparatus collapse too. DOSH's ICOP notes that deaths often follow inhaling toxic gases. The hazards are often invisible and odourless, and a space that was safe yesterday can be deadly today.

The Industry Code of Practice for Safe Working in a Confined Space 2010 is an approved industry code of practice under section 37 of OSHA 1994. Section 38 allows it to be used in proceedings, so departing from it without an equally safe method is hard to defend.

Recognising a confined space

The ICOP defines a confined space as an enclosed or partially enclosed space that:

• is at atmospheric pressure during occupancy
• is not intended or designed primarily as a place of work
• is liable at any time to (i) have harmful levels of contaminants, (ii) have an oxygen deficiency or excess, or (iii) cause engulfment
• could have restricted means for entry and exit

A person whose head or upper body is inside the space is treated as having entered it (paragraph 1.2.3). The ICOP does not apply to underground mining or to spaces not at atmospheric pressure.

The ICOP's examples include storage tanks, boilers and silos with manholes; open-topped spaces such as pits; and pipes, sewers, tunnels, shafts and ducts. Construction examples:

• manholes and sewers
• sumps and wet wells
• lift pits
• box culverts
• water tanks
• basement tanks and pump rooms
• deep narrow shafts and caissons
• ducts and service tunnels
• the inside of large precast units

Whether a trench or pit is a confined space depends on the assessment, not on a fixed depth.

Hazardous atmosphere

Under the ICOP a hazardous atmosphere is one that may expose workers to death, incapacitation, inability to self-rescue, injury or acute illness from:

Typical construction sources:

• hydrogen sulphide and methane in sewers and wet wells
• carbon monoxide from petrol engines and generators
• carbon dioxide and nitrogen that displace oxygen
• solvent vapours from coatings and adhesives
• oxygen used up by rusting steel or rotting matter
• oxygen enrichment from leaking cutting gas

Other confined space hazards include engulfment in water, silt or granular materials; heat; machinery; and poor lighting and access.

Roles and training (ICOP section 12)

All four trained categories take a refresher course every two years, using a DOSH-approved module. The employer keeps training records.

Health fitness

• An occupational health doctor issues a health fitness certificate valid for two years, after health surveillance using the ICOP's checklist (paragraph 11.3).
• Each authorised entrant declares in writing that they are fit before each entry (paragraph 11.4).

Preparing the space

1. Assess first. Decide whether entry can be avoided, for example with remote cameras, long-reach tools or outside cleaning.

2. Isolate (ICOP section 7):

   • Positive isolation of pipes, ducts, drains and conveyors, by blanking or disconnecting. Closing a valve is not positive isolation.
   • De-energise and lock out or tag out machinery such as mixers and agitators, and deal with stored energy.

3. Clean, purge or ventilate to remove contaminants.

4. Ventilate. With continuous forced ventilation:

   • no entry until the ventilation has removed any hazardous atmosphere
   • air directed to where people work, from a clean source, and kept running until everyone is out
   • periodic retesting (paragraph 8.7.2)
   • never "sweeten" the air with oxygen

5. Test the atmosphere. The authorised gas tester tests from outside before anyone enters, in this order:

   • oxygen first
   • then flammable gases and vapours
   • then toxic gases and vapours

   Test at several levels and record the results on the permit. Continue monitoring during entry, with personal gas detectors for entrants.

6. Equip. Provide lighting suitable for the atmosphere, communication equipment, means of entry and exit (ladders, a winch and tripod), PPE, and emergency and rescue equipment.

7. Sign-post. Post confined space warning signs while permitted work is in progress (paragraph 4.2.7).

The permit to work (ICOP sections 5 and 6)

• The permit is issued by the permit issuer and accepted and signed by the entry supervisor, and posted at the entry portal.
• Contents:
  • the space
  • the purpose of entry
  • the date and authorised duration
  • the names of the authorised entrants
  • the permit issuer, entry supervisor and standby person
  • the hazards
  • the isolation, purging and ventilation measures
  • acceptable entry conditions and test results
  • communication and rescue arrangements
  • equipment
  • other permits, such as hot work
• Duration: no longer than the task or 8 hours, whichever is shorter. It can be extended once for up to 4 hours by the entry supervisor if conditions are unchanged.
• The entry supervisor cancels the permit if a prohibited condition arises, and closes it when work is complete, followed by a debrief.
• The confined space permit is the overriding permit over other permits, such as hot work.

Rescue

• Retrieval systems for non-entry rescue are used whenever an authorised entrant enters, unless they would increase the overall risk or would not help the rescue (paragraph 10.8):
  • each entrant wears a chest or full-body harness with a retrieval line
  • the line is attached outside the space to a mechanical device or fixed point, so rescue can begin at once
  • a mechanical device must be available for vertical spaces more than 1.5 m deep
• Rescue procedures must be planned in advance: who rescues, with what breathing apparatus, how the casualty is lifted, how the emergency services are called, and first aid and resuscitation.
• Untrained, unprotected entry to rescue is forbidden. The standby person summons rescue and attempts non-entry rescue only.

Scenario: the sewer manhole

A pipe-laying crew needs to connect to an existing sewer through a 4 m deep manhole. The foreman suggests "just a quick look" without testing. The SSS stops the entry and arranges:

1. A permit issued by a trained permit issuer, with a separate registered entry supervisor.
2. Isolation of upstream flows by plugging, with the sewer operator's agreement.
3. Forced ventilation from a clean source, and pre-entry tests from the top in the order oxygen, then flammables, then H2S and CO. All readings must be within limits before entry.
4. A tripod and winch with full-body harness and retrieval line, because the space is vertical and more than 1.5 m deep.
5. A trained standby person at the opening with a radio, and a rescue plan with breathing apparatus.
6. Checks that the entrants hold current training certificates and two-year fitness certificates, and that each has signed the fitness declaration.