Transcript Document

MODULE 4
Excavation
(Trenching & Shoring)
Excavation – Trenching & Shoring
• Excavating is one of the most hazardous
forms of construction activity due to the
possibility of cave-ins.
• Excavating emergencies are more likely to
result in a serious injury or fatality than any
other construction accident.
• Trench accidents result in approximately 100
fatalities per year.
Excavation – Trenching & Shoring
By Law all underground hazards shall be
identified before work begins.
Utilize ONE CALL – 811
Excavation – Trenching & Shoring
APWA Color Codes
• Proposed Excavation
• Temporary Survey
• Electrical
• Gas
• Communications
• Potable Water
• Irrigation
• Sewer
Excavation – Trenching & Shoring
• Site workers are those
employees working on a
site or location that has an
excavation project.
• Excavation Workers are those employees
working on the excavation project
• Site workers are not authorized to work on
the excavation project.
Excavation – Trenching & Shoring
• A competent person is defined as one who is
capable of identifying existing and
predictable hazards in the surroundings, or
working conditions which are unsanitary,
hazardous, or dangerous to employees and
who has the authority to take prompt
corrective measures to eliminate them
Excavation – Trenching & Shoring
• Inspections
– Inspections must be performed by the competent
person
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Prior to start of work
As needed throughout shift
Daily
After rainstorms
Other hazard changes
Exposure reasonably expected
Excavation – Trenching & Shoring
• Work Practices
– Methods to prevent cave-ins
• Shielding and shoring
• Relies on mechanical structures
– Sloping and benching
• Based on soil type
Excavation – Trenching & Shoring
• Work Practices
– Good work practices shall include proper training
of all employees on dangers associated with
trenching and shoring.
– No employee shall be allowed on or around an
excavation without proper personal protective
equipment including atmospheric monitoring
devices.
Excavation – Trenching & Shoring
• No employee shall be allowed on or around
an excavation that does not have a
protective system in place, if necessary.
• Atmospheric testing shall be done before
entering the trench. Additional monitoring
shall be done as per company requirements.
• Means of exit must be within 25 feet of
lateral travel if greater than four feet in
depth.
Excavation – Trenching & Shoring
• Employees shall not work in excavations
where there is an accumulation of water
unless precautions have been taken to
protect employees.
– Precautions should include but are not limited to:
• Special support or shield systems
• Water removal or control
• Safety harness with lifeline
Excavation – Trenching & Shoring
• Hazards
– Oxygen deficient atmospheres.
– Loose rocks or soil.
– Overhead loads being carried/lifted by digging
equipment.
Excavation – Trenching & Shoring
• Personal Protective Equipment (PPE)
– Respirators – employees must be fit tested and
have proper training before use.
• Hazardous Atmospheres
– <19.5% or >23.5% Oxygen (MN 5207.300)
– Combustible gas >10% LEL (LFL)
– Concentrations of toxic materials > TLV
established by ACGIH
Excavation – Trenching & Shoring
• Some trenches qualify as a confined space.
Therefore compliance with the Confined
Space regulations would be required.
• Atmospheric testing shall be done:
– Before employees enter the area
– Periodically to ensure the atmosphere is still safe
– Periodic testing shall increase if you are
operating equipment in the trench.
Excavation – Trenching & Shoring
Emergency & Non-Entry Rescue
• In the event of an emergency situation
requiring rescue, personnel SHALL NOT
attempt to enter an unprotected trench to
perform rescue.
– Call emergency services in your area.
– Rescue services that can be performed safely
from outside the excavation, such as hoisting a
harnessed victim, shall be undertaken.
Excavation – Trenching & Shoring
• Other rescue equipment shall include:
– Breathing equipment
– Basket stretcher
– Attendees
Hydrogen Sulfide
H2S
Hydrogen Sulfide
• Hydrogen Sulfide (H2S) gas is deadly in
relatively low concentrations.
• H2S gas is created by the decomposition of
animal or vegetable matter.
• H2S gas may be found in oil and gas wells,
storage tanks, sewers, mines,
gas plants and refineries.
• What you don’t know can
hurt you!
Hydrogen Sulfide
• Hydrogen Sulfide (H2S) gas is referred to by
many names:
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Rotten egg gas
Stink gas
Sour gas
Sulfureted Hydrogen gas
Sewer gas
Devil’s breath
Hydrogen Sulfide
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Greatest danger is inhalation
SPECIFIC TRAINING IS REQUIRED
Use of respirator
Signs posted
Areas monitored
Hydrogen Sulfide
• (H2S) Properties and Characteristics
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Toxic
Colorless
Offensive odor
Soluble
Corrosive
Heavier than air
Flammable
Produces toxic bi-products
Hydrogen Sulfide
Possible Symptoms of H2S Exposure:
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Eye irritation
Fatigue
Throat irritation
Skin irritation
Headache
Nausea
• Dizziness
• Loss of
consciousness
• Vomiting
• Irrational behavior
• Coughing
• Excitement
Hydrogen Sulfide
• Toxicity Levels:
– 20 ppm Permissible Exposure Limit (PEL)
– 15 ppm Short Term Exposure Limit (STEL)
– 100 ppm Immediately Dangerous to Life and
Health (IDLH)
– 1000 ppm Dead Right There (DRT)
Hydrogen Sulfide
• If the event of an H2S alert and the monitor alarm
sounds, employees are to evacuate quickly
moving up wind or cross wind, to high ground.
• Check the wind sock or guy wire flags to
determine wind direction.
Fire Safety
&
Emergency Evacuation
Fire Safety – Prevention and Protection
• Actions to be taken:
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Prevent or reduce likelihood of a fire
Alert the presence of a fire
Enable survival
Reduce damage
Know the level of training of each employee
Respond only to the level of training
Fire Safety – Prevention and Protection
• Four Elements of a Fire:
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Air
Fuel
Heat
Chemical Reaction
• All four elements are needed.
• When one leg of the fire triangle is removed
combustion stops.
Fire Safety – Prevention and Protection
• Class A Fires & Extinguishers
• Work by cooling the fire.
• Class B Fires & Extinguishers
• Work by blanketing the fuel.
• Class C Fires & Extinguishers
• Work by displacing oxygen, smothering the fire.
• Class D Fires & Extinguishers
• Work by separating the fuel from the oxygen.
• Class K Fires & Extinguishers
• Work by blanketing the fire with surfactant.
D
K
Fire Safety – Prevention and Protection
• Extinguishing Agents
Class
Contents
A
Water
AB
Chemical Foam or Gel
BC
Carbon Dioxide
BC
Dry Chemical
BC
Liquefied Gas
ABC
Dry Chemical or Halon Substitute
K
Sodium or Potassium Bicarbonate
Fire Safety – Prevention and Protection
• Remember the PASS System
– Pull
– Aim
– Squeeze
– Sweep
Fire Safety – Prevention and Protection
• Pull the Pin
– This will allow you to
discharge the extinguisher.
• Aim
– Aim at the base of the fire
instead of the flames.
Fire Safety – Prevention and Protection
• Squeeze the Handle
– This will release the
pressurized extinguishing
agent.
• Sweep
– Sweep from side to side
until the fire is out.
Fire Safety – Prevention and Protection
• HOT WORK
– Examples
• Welding
• Flame Cutting
• Grinding Using a torch
• Obtain Hot Work permit prior to
performing any Hot Work activity
Fire Safety – Prevention and Protection
• FIRE WATCH
– Duties
• Have appropriate fire extinguisher readily available
• Ensure conditions of permit are enforced
• Remain at hot work area for at least 30 minutes after
completion of the hot work
• Prior to beginning work, discuss the Emergency Action
Plan.
Emergency Evacuation
• The immediate and rapid movement of
people away from the threat and immediate
danger.
• Emergency evacuation should be planned
prior to any type of emergency
that could exist in your field of
operation.
Emergency Evacuation
• All employees shall be trained and familiar
with the emergency evacuation program.
• The program shall be displayed in an
accessible area for all employees.
• Keep all exits clear of obstructions.
• Know your assembly point in the event of an
evacuation.
• Be familiar with the company notification
protocol.
Electrical Safety
Electrical Safety
• Electricity is a silent and invisible force that can kill
without warning if ignored – treat with respect and
caution.
• Electricity takes multiple paths, flowing through the
path of least resistance.
• The body can act as an excellent conductor since it
is made up of water, chemicals and minerals.
• The body can bridge the gap between two voltage
levels resulting in an electric shock.
Electrical Safety
Electrical Hazards
– Sparks from static or equipment
• Fires
• Explosions
– Faults in lines or equipment
• Fires
• Explosions
• Shocks
Electrical Safety
• Causes of Electrical Hazards
– Hazardous conditions
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Wet surrounding
Outdoor Activities
Cramped spaces
Explosive atmospheres
Arcing
Equipment wear and tear
Electrical Safety
• Safe Work Practices
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Lockout/Tagout
Proper Authorization
Electrical protective equipment
Keeping a safe distance from energized circuits
Equipment Inspection
Using proper tools (GFCI, Insulated tools)
Electrical Safety
• Working Near Exposed Parts
– Energized Equipment – anything connected or
contacted to an electrical source. Has the power
on!
– De-Energized Equipment – being free from any
electrical connection to a source. Has the power
disconnected from the source!
Example: lockout/tagout
Electrical Safety
De-Energized Parts
• Treat any conductors and parts of electric
equipment as energized that have been
de-energized.
• Lockout/Tagout should
always be used.
Electrical Safety
Energized Parts
– Only qualified employees:
• May work on or with exposed energized lines or parts of
equipment.
• May work in areas containing unguarded, un-insulated
energized lines.
Electrical Safety
Overhead Line Safety
– Don’t operate equipment around overhead power
lines unless you are authorized to do so.
– If an object must be moved in the area of
overhead power lines, appoint a competent
worker as a spotter.
– Never touch an overhead line.
– Never assume lines are dead.
Electrical Safety
– When a machine is in contact with overhead
lines, DO NOT allow anyone to come near or
touch the machine.
– Never touch a person who is in contact with a live
power line.
– If you are in a vehicle that is in contact with an
overhead power line, DO NOT LEAVE THE
VEHICLE and do not touch any metal parts within
the vehicle.
– Avoid storing materials under or near overhead
power lines.
Electrical Safety
– Portable equipment is not part of a fixed
installation but when used is connected to a fixed
installation by means of a flexible cable, plug and
socket.
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Never raise or lower by cord
Ensure there are grounding prongs
No exposed or repaired wiring
Approved portable electrical equipment
Use a portable GFCI
Electrical Safety
• Inspection
– Portable Electrical Equipment
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Ensure ground connection on plug ends
Ground prong is not removed
Inspect prior to use
Avoid long extension cords
Use approved couplers
Replace damaged extension cords
Electrical Safety
• Inspection
– Ground Fault Circuit Interrupters
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Best protection from electrical injury
Interrupts circuit
Protects people, not equipment
Test periodically
Installed between extension cord and load
Electrical Safety
• Inspection
– Welding cable
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Inspect prior to use
No splices within 10 feet of holder
Repair or replaced if damaged
Connect appropriately
Never wrap around body part
Electrical Safety
• Avoiding the hazards
– Never use broken or faulty equipment
– Electrical PPE
• Must be inspected
• Includes
– Gloves
– Matting
– Blankets
- Covers
- Line hoses
- Sleeves
Electrical Safety
• During well servicing operations, grounding
is to be provided between the rig and
wellhead with a grounding cable
securely connected in the casing.
• Derrick personnel must vacate
the derrick during thunderstorms
and all workers are to move
away from the derrick.
Lockout/Tagout
Lockout / Tagout
• Lockout is the process of blocking the flow
of energy (electrical, fluid, air etc.) from a
power source with a blocking device to
eliminate the power to disable the
equipment.
• A lockout device may be a lock,
chain, block or special locking
device that keeps the power in
an “off” position.
Lockout / Tagout
• This program does not apply to handheld
power tools or stationary equipment whose
electrical power may be controlled by the
unplugging of equipment from the energy
source.
Lockout / Tagout
• Types of Energy Sources
– Kinetic Energy – the force caused by the motion
of an object.
– Potential Energy – the force stored in an object
that isn’t moving.
Lockout / Tagout
Energy sources may include any one or combination of
the following:
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Electrical
Mechanical
Hydraulic
Thermal/steam
Gravitational
All forms of potential
stored energy
– Fluid under
pressure/oil, water
– Gases
– Pneumatic
– Nuclear
– Chemical
Lockout / Tagout
• Employees are to be trained in LO/TO
procedures.
• Training must be done prior to participation
in the program, and if a change occurs.
– Authorized Employee: person who physically
locks and tags equipment for maintenance or
servicing.
– Affected Employee: person who may operate or
work in areas where equipment is subject to the
LO/TO process.
Lockout / Tagout
Roles and responsibilities
– Authorized Employees involved in the lockout
must be knowledgeable of the type and
magnitude of the energy, the hazards of the
energy to be controlled, and the method or means
to control the energy before turning off
equipment.
Lockout / Tagout
• Authorized Employees will notify all Affected
Employees (before and after) the LO/TO and
the prohibition of attempts to restart or
energize equipment.
• Equipment shall be turned off or shut down
using the established procedures.
Lockout / Tagout
• Lockout the equipment with a personal lock
used by the Authorized Employee in charge.
• The tag placed on the equipment should be
dated and signed by the person performing
the work.
Lockout / Tagout
• The Authorized Employee must affix lockout
or tagout devices to each energy source or
isolating device.
• The device shall be attached in a manner
that will hold the energy isolating devices in
a “safe” or “off” position.
• Turn the power source on to assure the
power source has been deactivated.
• Always look for hidden energy sources.
Lockout / Tagout
• No lock shall be affixed without a tag dated
and signed by the person performing the
isolation and stating the reason for the
lockout.
• It is policy to use locks whenever possible.
If this is not possible, a tag may be used.
– Tags must clearly state that movement of energy
isolating devices from the “safe” or “off” position
is prohibited.
Lockout / Tagout
– Where tagout devices are used with devices that
are capable of being locked, the tag attachment
shall be fastened at the same point at which the
lock would have been attached.
– Where a tag cannot be affixed directly to the
energy isolating device, the tag shall be located
as closely and safely as possible to the device.
– Guards and interlock devices cannot be used as a
substitute for lockout devices.
Lockout / Tagout
• Group Isolation: When a crew or group
performs service or maintenance, they must
use a procedure that provides ALL
employees a level of protection equal to that
provided by a personal LO/TO device.
– Each employee attaches a personal
LO/TO device to a group lockout
mechanism.
– Each employee will test at the start
station to ensure equipment is inoperable.
Lockout / Tagout
• Every power source has its own
procedure for lockout.
• The procedure may include:
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Pulling a plug
Opening a disconnect switch
Removing a fuse
Closing a valve
Bleeding a line
Placing a blind in a line
Lockout / Tagout
– Always look for hidden energy sources, since
some equipment has more than one power
source.
– After ensuring that all personnel are clear, the
equipment must be tested to verify that it is
properly isolated and will not operate..
Lockout / Tagout
• The following energy sources may be
encountered:
– Electrical –
• motors controllers, capacitors,
circuit breakers
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Pneumatic
Hydraulic
Fluids and gases
Mechanical
Blinding of Pipe
Lockout / Tagout
• Restoring Power to Equipment
– Individual locks may be removed
after each phase is complete by the
Authorized Employee.
– Clear the work area of non-essential employees
and equipment.
– Take a headcount to ensure all employees are
clear.
– After removal of lock and tag devices, notify the
Affected Employees.
Lockout / Tagout
Locking & Tagging Device
– Each unit should provide standardized tags and
individually keyed or combination locks as
required to execute the LO/TO process.
– Tag devices must be of a non-reusable type,
attachable by hand, self-locking.
– Critical systems locked and tagged should
include identity and job title of person installing
the lock and tag.
MODULE 4
REVIEW