Transcript Confined Spaces WISHA Part One - Home

Confined Spaces – Part 1
An Overview of the
WISHA Confined Spaces
Standard
Purpose of This Module
This two-part module provides basic information
for employers about the hazards of confined
spaces, how to control these hazards and what
WISHA requirements apply when employees
enter confined spaces.
Some employers may elect to contract out
confined space work. In those cases, employers
are obligated to fully inform contractors of the
confined space hazards at their facilities.
This overview does not replace the confined
spaces standard. For the complete WISHA
confined space rule requirements, see Confined
Spaces Chapter 296-62 Part M.
Confined Spaces Overview
Part 1 of this overview will cover the following:
How to identify a confined space,
Confined space hazards,
How to control or eliminate the
hazards.
Identifying the space
What is a confined space?
A confined space is an enclosed
space that:
is large enough to get whole
body inside,
is not designed for human
occupation,
has limited or restricted
entrance or exit.
It must have all three characteristics to be a confined space.
Identifying Confined Spaces
Examples of confined spaces
Manholes
& Sewers
Tanks
Boilers
Grain storage bins
Other examples include vaults, pipelines, tank cars, and ship holds
Hazards of Confined Spaces
Basic Principles
Confined spaces can be deadly.
Some confined spaces are more hazardous
than others.
Confined space conditions can change rapidly
from no hazards to life-threatening hazards.
Some confined spaces are so hazardous, a
written permit system is required for entry.
The hazards of confined spaces can often be
controlled or eliminated before entering.
For a description of an actual
confined space fatality, click here.
Hazards of Confined Spaces
What are the main hazards of confined spaces?
• Hazardous atmospheres
• Engulfing materials
• Entrapment
• Moving parts
• Electricity
Hazard of Confined Spaces
When is a confined space so dangerous a
written entry permit system is required?
• When there is an actual or potential
“hazardous atmosphere” or
• when the space contains loose
material that can engulf a person, or
• when the space is configured in a way
that can trap a person, or
• when there is any other recognized
serious safety and health hazard.
Hazard Identification
A “hazardous atmosphere” in a confined space has
one or more of the following:
Flammable gas, mist or vapor
Flammable dusts
Oxygen content below 19.5% or above 23.5%
Air contaminant concentrations that would
cause death, incapacitation, or permanent
health problems
You must do air monitoring
to determine if a hazardous
atmosphere exists.
Hazard Identification
Hazardous Atmospheres – Flammable Gases,
Vapors and Dusts
Flammable gases, vapors or dusts will
ignite from a spark or flame if above a
level in the air called the “lower
flammable limit” (LFL).
Gas or vapor levels higher than 10%
of the LFL are considered hazardous
and the confined space cannot be
entered until levels are reduced.
Amounts above 10% of the LFL are
usually toxic as well.
LFL is sometimes called “LEL” – “lower explosive limit”
Hazard Identification
Example of flammable gas levels - Methane
Air
0%
Air
100%
Too Rich
Too Lean
Methane
0%
Boom!
5.3%
LFL
Methane
100%
15.0%
UFL
An open flame or a spark will cause an explosion when methane amount
is between 5.3% and 15%, the upper flammable limit (UFL).
Hazard Identification
Hazardous Atmospheres – Oxygen Deficiency
A reduction in oxygen is caused by tank rusting, microbe
activity, or replacement by another gas.
Lack of oxygen can cause a person to immediately
collapse and die.
Normal air contains 21% oxygen. A space with oxygen
content below 19.5 % is considered “oxygen deficient”.
21% 19.5%
0%
Oxygen content
Oxygen deficiency exists
Hazard Identification
Effects of Oxygen Deficiency
% Oxygen
Symptoms
19.5% - 16%
Fatigue, mild impaired coordination
16% - 12%
Increased breathing rate and pulse;
impaired coordination, perception or
judgment
12% - 10%
Further increased breathing rate, blue
lips, mental confusion
10% - 8%
Fainting, nausea, vomiting, mental
confusion within few minutes
8% - 6%
Collapse, death within 8 minutes
6% - 0%
Coma within 40 seconds, death
Using an “inerting gas” like nitrogen, to counteract
flammable vapors will result in an oxygen deficiency.
Hazard Identification
A word about oxygen-enriched atmospheres
A confined space with oxygen
amount above 23.5% is
considered “oxygen-enriched”.
The source of extra oxygen is
typically from leaking oxygen
cylinders used for oxy-acetylene
torches.
Oxygen above 23.5% is a fire
or explosion hazard.
Green tanks contain oxygen
Hazard Identification
Hazardous Atmospheres – Toxic Chemicals
• At very high levels, most chemicals
in the air can be immediately lifethreatening or cause permanent
bodily harm.
• At lower levels, chemicals in the
air can still cause harm.
• Most chemicals have “permissible
exposure limits” (PELs) which will
cause harm if exceeded.
• Even non-toxic or low-toxic chemicals can
replace oxygen if levels are high enough.
Hazard Identification
Hazardous Atmosphere – Toxic Chemicals
The most common toxic chemicals in
confined spaces fatalities are hydrogen
sulfide and carbon monoxide.
Other toxic chemicals can include welding
fumes, vapors from liquid residues in
storage tanks, or chemical products used
in the confined space.
Chemicals can quickly reach toxic levels in
the air of a confined space, especially
gases, solvent vapors or sprayed products.
Hazard Identification
Hazardous Atmospheres–Hydrogen Sulfide (H2S)
Hydrogen sulfide gas is commonly found in sewers.
It can be instantly fatal at higher levels in a confined
space.
Disturbing sewage sludge can release more hydrogen
sulfide gas.
30
100
200
600
1000
2000
H2S in ppm
Smell
strong
odor
Loss of
smell
Coughing,
red eyes
Unconscious
in 30 min.
Instant
collapse
Death in
minutes
Hazard Identification
Hazardous Atmospheres – Carbon Monoxide (CO)
Carbon monoxide comes from
operating internal combustion
engines in or near confined
space.
Propane-powered engines
also emit carbon monoxide.
Fatal levels of CO are quickly
reached in confined spaces.
The PEL for CO is 35 ppm. To
see the effects of CO, click here
Propane-powered
manlift in a large tank
Hazard Identification
What are the Hazards of Engulfing Material?
Engulfing materials include liquids or
loose solids such as grain, sand or
other granular material.
People cannot escape when caught
in moving loose solids and usually
suffocate.
Workers often get engulfed when
in-feed or out-feed lines are
inadvertently opened or activated.
Hazard Identification
What is Entrapment?
The space is configured in a way that can trap a worker,
for example, sides sloping towards the center
Gravel hopper with sloping internal sides
Hazard Identification
Other Recognized Hazards
Electrical lines, steam lines
or hydraulic lines
Mechanical hazards
(moving parts)
Hazards caused by the work
(welding, painting etc.)
Controlling the Space
The hazards of a confined space can be be
controlled in the following ways:
• Prevent employee entry.
• Remove or reduce hazards in the
space first, before a person enters.
• If hazard cannot be controlled,
you must use a written permit
system to enter safely.
See Part 2 for more information on a written permit system.
Controlling the Space
Warning employees and controlling access
Post warning signs at the entrance of
confined spaces.
Limit employee access to confined
spaces by using entry barriers or locks.
Make sure that unauthorized workers do
not enter the confined space.
Hazard Control
How To Control Hazardous Atmospheres
Drain or pump out liquid contents,
if any.
Blank off all in-feeding lines.
Air test and ventilate.
Continue ventilating constantly.
If possible, remove any sludge
from outside the confined space.
Exit space if conditions
deteriorate.
Hazard Control
Hazardous Atmospheres Dangers
It is difficult to eliminate
hazardous atmospheres in
most sewers lines.
Tank sludge or sewer sludge
can release toxic gases during
cleanup.
Toxic or flammable gases can
exist in pockets or layers.
Hazard Elimination
How To Eliminate Physical Hazards
Lock-out moving parts
Blank or block steam pipes
and product in-feeding pipes.
De-energize electrical parts or
wiring
If Hazards Can’t Be Eliminated
If hazards cannot be completely eliminated,
there are only two options:
a complete written permit system, or
“alternate procedures.”
Both require training of employees.
See Part 2 for more information on entry procedures.
Additional Information
More information is available on WISHA webpage
This presentation is just an overview and
does not cover all requirements.
For more information on how to put
together a confined space program for
your workplace, go to:
http://www.lni.wa.gov/wisha/publications/App/Document/ConfSpac.doc
For additional assistance, you can call one of our
consultants. Click below for local L & I office
locations:
http://www.lni.wa.gov/wisha/consultation/regional_consultants.htm
Confined Space Quiz
Question 1
Which of following are considered confined spaces?
a) A sewer manhole
b) A sub-basement vault with only one door
c) A 20 foot deep ditch
d) A 30-gallon drum
Confined Spaces Quiz
Question 2
When can a hazardous atmospheres be fatal?
a) When there is not enough air
b) When there is 2% methane
c) When there is 10% oxygen
d) When there is no ventilation
Confined Spaces Quiz
Question 3
Which of the following is not a good way to
control hazardous atmospheres?
a) Ventilate for two hours before entering
b) Drain or pump out liquid contents
c) Air test and ventilate continuously
d) Remove any sludge from outside the space