Confined Space

Confined Space Defined
A confined space is not normally designated or intended for human occupancy. Special precautions are required to protect workers who must enter from flammable or harmful atmospheres, oxygen depletion or enrichment, or situations of possible entrapment. Examples include, but are not limited to: tanks, silos, storage bins, process vessels, pipelines, sewers, double hulls, underground utility vaults, boilers, pits, vats and tunnels.

Confined spaces have the following general characteristics:

• Not designated or intended for human occupancy;
• Provide limited means of entry and exit;
• Have poor natural ventilation with the presence of or the potential for a dangerous atmosphere;
• Pose another danger such as entrapment;
• Require special precautions prior to and during entry, including the means for immediate rescue.

Prohibition
No Thompson Rivers University employee or student shall enter a confined space in which a harmful atmosphere exists or may develop until:

1. tests to determine the nature and quantity of harmful vapours, gases, fumes, mists, dusts and oxygen deficiency have been made and recorded; and
2. written work procedures have been established to ensure a safe environment for the worker.

These spaces include tanks, vessels, sewers, utility bunkers or other spaces which may allow harmful substances to accumulate in the atmosphere.

TRU Confined Space Entry Procedures 
TRU Confined Space Entry Permit 


Sampling for Harmful Substances

1. Utility Bunkers
   Grab samples for % Oxygen, C02 and CO will be taken and results logged in each bunker prior to employee entry.
   Where levels of CO2 or CO exceed 50% of the TWA or TLV, or % Oxygen falls below 18%, the Health and Safety Coordinator shall provide written procedures for protecting employees.
   
   
2. Sewers, Tanks, Vessels
   Samples for % Oxygen, % combustibles, S02, C02 and C0 will be taken and results logged prior to employee entry.
   Where levels of SO2, CO2, or CO exceed 50% of the TLV or TWA, or % Oxygen falls below 18%, or % combustibles exceed 20% for the lower explosive limit of a flammable substance, the Health and Safety Coordinator shall provide written procedures for protecting employees.

Procedures

1. Where the tests made indicate unsafe conditions, the confined space shall be ventilated and/or cleaned and retested to ensure that the harmful substances are below acceptable levels as per WCB Health and Safety regulations and that the oxygen content is greater than 18% before a worker enters the confined space.
   
   
2. Where tests made indicate the presence of harmful or explosive substances and it is not practical to provide a safe, respirable atmosphere, then:
   1. the worker entering the confined space shall wear respiratory and personal protective equipment as outlined by WCB Health and Safety Regulations, and
   2. the concentration of flammable substances shall be maintained below 20% of the lower explosive limit (LEL) of that substance or substances and determined by repeated testing, and
   3. where flammable or explosive gases or liquids are present all sources of ignition shall be eliminated or controlled.
   
   
3. A worker who is required or permitted to enter a confined space in which a harmful substance exists or may develop or where the worker may become trapped by material shall, in addition to the above,
   1. wear a safety harness or belt of a type which will keep the worker in a position to permit rescue, and
   2. have a life-line attached to the belt or harness which is tended at all times by another person, stationed outside the entrance to the confined space, who shall be equipped for and capable of effecting rescue.
   
   
4. Where one or more workers enter a confined space, provision shall be made to prevent the entanglement of life-lines and other equipment.
   
5. A worker entering a confined space shall be:
   1. attended by, and in communication with, another person stationed at or near the entrance, or
   2. provided with a means of continuous communication with a person outside, and
   3. visually checked by a designated person at intervals as often as may be required by the nature of the work to be performed.
   
   
6. Where work is carried out in any confined space:
   1. the confined space shall be ventilated continuously, and
   2. tests for harmful or explosive substances and oxygen deficiency shall be made and recorded immediately prior to entry, after any interruption in the work procedure, and at intervals to ensure the continuing safety of the workers in the confined space.

Blanking Requirements

1. Before a worker enters a confined space:
   1. piping containing hazardous substances or substances under pressure or so located to allow hazardous substances to enter such space, shall be disconnected, blanked or blinded off; or
   2. where it is impractical to employ blanks or blinds, as in welded piping systems, written work procedures shall be developed and implemented to ensure equivalent protection to all workers exposed to the hazard, and
   3. the closing of a valve or any line will not be acceptable as a substitute for blanking or blinding.
   
   
2. When blanking or blinding a piping system, blanks or blinds shall be of sufficient strength and so installed as to provide adequate safety for the particular conditions of anticipated pressure, temperature and service.
   
   
3. Visual indication that a blank or blind has been installed shall be provided at the point of installation.
   
   
4. When required, a gasket shall be installed on the pressure side of blanks or blinds and flanges shall be tightened to make the blanks or blinds effective.
   
   
5. Where threaded lines are used threaded plugs or caps shall be used to blank the lines.
   
   
6. Records shall be kept which identify the blanked lines and the locations of blanks and blinds.

Additional Reference
For additional information on this topic, consult the WCB Handbook entitled "Confined Space Entry - A Manual of Standard Practices".