Learning Objectives
Define a confined space
Identify the various types of confined spaces
Describe various hazards associated with confined spaces
Highlight potential confined space precautions and controls
Muizz AnibireCivil Engineer/Loss Prevention and Risk Engineering Consultant à Daptoy Engineering Services
Construction Safety Training_Session 03_Confined Spaces and Underground Works
1. Dammam Community College
Safety Technology Program
Construction Safety Training
SHORT COURSE
Instructor: Mr. Muizz Anibire, MSc
Tel: +966501296203, Email: muizzanibire10@gmail.com
2. Define a confined space
Identify the various types of confined spaces
Describe various hazards associated with confined spaces
Highlight potential confined space precautions and
controls
Learning objectives
3. Confined Spaces
A confined space can be defined as any space of an enclosed nature which
has limited means of access and egress, restricted natural ventilation and is not
intended for continual occupancy by persons.
4. Confined Spaces
The hazards in confined spaces have caused the deaths of many
workers and those who were trying to rescue them.
On average 15 people each year are killed in confined spaces.
As with all hazardous situations, work should only take place in a
confined space if it is unavoidable.
The Confined Spaces Regulations require that:
No person at work shall enter a confined space for any
purpose unless it is not reasonably practicable to achieve that
purpose without such entry
Other than in an emergency, no person shall enter, carry out
work or leave a confined space otherwise than in accordance
with a safe system of work, relevant to the specified risks.
12. Hazards in Confined Spaces
Hazards associated with confined spaces include:
Asphyxiation due to oxygen depletion
Poisoning by toxic substance or fumes
Explosions due to gases, vapours, and dust
Fire due to flammable liquids, vapours and oxygen enrichment
Fall of materials leading to possible head injuries
Electrocution from unsuitable equipment
Difficulties of rescuing injured personnel
Drowning due to flooding or free flowing grains
Excessive heat leading to heat stress
Claustrophobic effects due to restricted space
Diseases from animal wastes, infected materials or micro-organisms,
e.g. Fungal infections, tetanus, weil’s disease and pigeon droppings.
14. Asphyxiation
When oxygen levels fall to 17%, the physical and mental abilities of
workers become severely reduced.
As the concentration falls below 17%, unconsciousness and death
follow very rapidly.
In confined spaces, operations, like welding and cutting, consume
oxygen very rapidly. Poisonous gases or vapours can be caused by
leaching from contaminated surrounding land or by the
concentration of gases in sewers or manholes.
15. Confined Space Assessment
The assessment will involve the following items:
Any previous contents in the confined space
Any residues that have been left in the confined space, for
example sludge, rust or scale, and details of gases or vapours
which may be generated if these substances are disturbed
Any contamination which may arise from adjacent plant,
processes, services, pipes or surrounding land, soil or strata
Any oxygen deficiency and enrichment. There are very high
risks if the oxygen content differs significantly from the
normal of 20.8%
The physical dimensions and layout of the space since these
can affect air quality
16. Confined Space Assessment
The assessment will involve the following items:
o the use of cleaning chemicals and their direct effect or interaction
with other substances
o any sources of ignition for flammable dusts, gases, vapours,
plastics and the like
o the need to isolate the confined space from outside services or
from substances held inside such as liquids, gases, steam, water,
fire extinguishing media, exhaust gases, raw materials and energy
sources
o the requirement for emergency rescue arrangements including
trained people and equipment.
17. Confined space controls and precautions
The main elements of a safe system of work which may form the
basis of a permit to work are as follows:
the type and extent of the supervision of the work
the competence, training and instruction of the workforce
the stipulation of a minimum gang size for large confined spaces
such as reservoirs
details of any information required by the workforce
the methods of communication between people inside, from
inside to outside and to summon help in an emergency
the testing and monitoring of the atmosphere inside the confined
space for hazardous gas, fume, vapour, dust and the concentration
of oxygen
the gas-purging of toxic or flammable substances with air or inert
gas such as nitrogen
18. Confined space controls and precautions
The main elements of a safe system of work which may form the
basis of a permit to work are as follows (contd.):
the provision of good ventilation sometimes by mechanical
means
if appropriate, the cleaning of the confined space before the work
commences
the careful removal of residues using appropriate equipment
which will not cause additional hazards
the effective protection from gases, liquids and other flowing
materials by the removal of redundant piping, the blanking of
pipes and the locking of valves
19. Confined space monitoring arrangements
Before any work commences in the confined space, the site
supervisor must arrange for any necessary environmental surveys and
sampling needed to protect the health of the workforce.
Continuous gas monitoring using electronic instruments should be
used in preference to ‘spot’ detection devices.
The workforce should also be given health checks periodically to
ensure that they are not suffering any claustrophobic effects or
problems with the wearing of breathing apparatus.
All breathing and resuscitation apparatus, rescue equipment and
emergency alarms must be regularly checked and in some cases
recalibrated.
First aid provision must be checked regularly as must the
accreditation of first aiders.
20. Confined space emergency arrangements
Before people enter a confined space suitable and sufficient
emergency and rescue arrangements must be in place.
contingency plans to deal with an emergency in the confined
space. Such plans must include details of rescue teams
together with individual responsibilities
the contact names and telephone numbers of the local
emergency services
the details of the communication arrangements from inside
the confined space
the provision and maintenance of the rescue and resuscitation
equipment
the raising of the alarm, alerting the rescue team and
maintaining close supervision of the workforce inside the
confined space
22. Links to Further Resources on Confined Spaces
1. https://www.assp.org/news-and-articles/2017/12/21/the-seven-steps-of-
confined-space-rescue
2. https://www.assp.org/news-and-articles/2019/11/04/six-questions-that-help-
define-confined-space-safety
3. https://www.assp.org/standards/standards-topics/confined-spaces-z117-1
4. http://aeasseincludes.assp.org/professionalsafety/pastissues/056/07/042_046_
F3Taylor_0711Z.pdf?_ga=2.144076661.1944471147.1574072150-
1740919616.1572602101
5. http://aeasseincludes.assp.org/professionalsafety/pastissues/059/10/F3McMa
nus_1014.pdf?_ga=2.144076661.1944471147.1574072150-
1740919616.1572602101
6. http://aeasseincludes.assp.org/professionalsafety/pastissues/063/06/F1_0618.
pdf?_ga=2.144076661.1944471147.1574072150-1740919616.1572602101
7. http://aeasseincludes.assp.org/professionalsafety/pastissues/047/05/014274na
.pdf?_ga=2.144076661.1944471147.1574072150-1740919616.1572602101
23. Knowledge Check
Q1 A confined space can be defined as any space of an
enclosed nature which has limited means of access and
egress, restricted natural ventilation and is not intended for
continual occupancy by persons.
T F
Q2 On average 15 people each year are killed in confined
spaces.
T F
Q3 Hazards associated with confined spaces include
asphyxiation due to oxygen depletion
T F
Q4 As the concentration falls below 17%, unconsciousness
and death follow very rapidly.
T F
Q5 Before any work commences in the confined space, the site
supervisor must arrange for any necessary environmental
surveys and sampling needed to protect the health of the
workforce.
T F