Entering and working in enclosed and confined spaces. Are they the same?

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I’m regularly asked, “what’s the difference between an enclosed space and a confined space?”

SO…here’s my response…

What is Enclosed Space?

An enclosed space is defined as any enclosed space that has limited openings for entry or exit, inadequate ventilation and is not designed for regular occupancy.

Because of the lack of ventilation within enclosed spaces, these areas generate and store toxic gases that are either produced from chemicals within the place or from leakage out of surrounding pipelines.

Air movement is almost entirely limited, meaning any flammable atmosphere is unable to be dispersed.

What is Confined Space?

A confined space is any enclosed or partially enclosed space with normal atmospheric pressure not designed or intended to be occupied by a person.

Confined spaces are likely to contain an atmosphere with unsafe oxygen levels and can often contain contaminants such as airborne gases, which can cause injury or death.

Similar to that of enclosed spaces, the possibility of engulfment within confined spaces is very real. Thus, it is crucial that occupants of confined spaces have a strong understanding of precaution, working safety equipment and solid communication processes with colleagues in place.

Examples of confined spaces include pits, underground sewers, tunnels, wells, tanks, etc.

On your vessel

As you can see from the above both have a lot of similar properties therefore require a number of the same safety precautions. Below are the four most prevalent hazards when entering enclosed or confined spaces.

  1. Fuel fumes: Fumes from fuel, in particular gasoline are a major hazard. Highly volatile and a leading cause of marine related explosions and fires, gasoline fumes, which are heavier than air, can easily accumulate in a vessel’s bilge due to improper refuelling or fuel system leaks. There, it’s only a spark away from causing a fire or explosion.
  2. Liquid Propane Gas (LPG): LPG vapor is heavier than air and tends to “flow” like water, seeking the lowest possible point. As a boat’s hull is essentially a watertight envelope, escaping LPG can be trapped in bilges or other low areas, where they can rapidly accumulate to explosive concentrations.
  3. Carbon Monoxide: Carbon monoxide (CO) is a potentially lethal gas produced when burning any carbon-based fuel (e.g., gasoline, wood, propane). CO is colourless, odorless, and tasteless, and mixes evenly with air, meaning it readily travels throughout a boat’s interior spaces. CO enters the body through the lungs and is readily absorbed into the bloodstream, where it displaces oxygen levels in the body and can lead to carbon monoxide poisoning.
  4. Hydrogen Sulfide: Hydrogen sulfide (H2S) is a colourless, toxic gas that is also flammable and highly corrosive. Symptoms of H2S exposure include skin and eye irritation, headaches, loss of balance, nausea, delirium, tremors, and convulsions. Inhalation of high concentrations of H2S can lead to rapid unconsciousness and death. H2S gas occurs naturally during the breakdown of organic matter.

How do I stay safe?

The first question is to ask, “is it an enclosed or confined space?”

Question number two is “what hazards are there when I enter the space?”

Let’s look at a couple of different scenarios for enclosed spaces…

  1. The bilge space of a vessel under 35mtr. My quick check list
  • open the relevant hatch, ensure the hatch is fully open and secured in place
  • ventilate the space
  • check if there are any noticeable fumes
  • advise another person that I’m entering the space
  • have a person stand watch
  1. The engine room on a vessel under 35mtr. This depends on if the engine room has ventilation/ extraction fans. My quick check lists follow…

With fans:

  • open the relevant hatch, ensure the hatch is fully open and secured in place
  • advise another person that I’m entering the space
  • have a person stand watch

Without fans:

  • open the relevant hatch, ensure the hatch is fully open and secured in place
  • ventilate the space
  • check if there are any noticeable fumes
  • advise another person that I’m entering the space
  • have a person stand watch(if necessary)

Confined Spaces

NO person should enter a confined space without the appropriate training. It’s critical that if you have confined spaces on your vessel you have a dedicated procedure for entering them. The key steps for entering any confined space are:

  • Ensure any person entering the confined space has the appropriate training
  • Complete a “Confined Space Entry Permit”
  • Undertake a Risk Assessment (this is part of the Entry Permit)
  • Ventilate the space
  • Test the air quality using certified testing equipment
  • Having lighting equipment available if required
  • Use breathing apparatus if required
  • Ensure clear communications
  • Ensure there are rescue procedures in place

This list is not comprehensive but only a guideline for entering confined spaces


Shorlink’s Recommendation

Number one recommendation is if you have confined spaces on your vessel or in the workplace ensure you have a procedure for entry and the required equipment and documentation available.

Failure to complete a Confined Space Entry Permit, including a Risk Assessment leaves you in a dangerous position in the event of an incident.


Tip

If you have confined spaces our tip is to have at least one person trained in confined space entry available. In the event entry is required you have a qualified person available to deal with potential hazardous issues.

The alternative is to have a person or company readily available if the need arises!