Safe use of Gas Cylinders - ConsultNet.IE

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©Consultnet Limited



Safe Use of
Cylinder Gases

©Consultnet Limited

Presentation Contents


Introduction to Gas Cylinder Safety


Main causes of Accidents


Main Hazards


Rules for Safe Working with Gas Cylinders


Gas Regulators


Flashback Arrestors


Hoses, Piping, Blow Pipes and Torches


Acetylene

unique properties


Handling Gas Cylinders


Transporting Gas Cylinders


Safe Storage


Cylinder Incident Response


Gas Cylinders Hazards in Your Workplace


Conclusions



©Consultnet Limited

Introduction


Compressed gases used in a variety of industrial and
laboratory situations


Compressed gases present a unique hazard. Depending on
the particular gas, there is a potential for simultaneous
exposure to both mechanical and chemical hazards


Gases can be:


Flammable or combustible


Explosive


Corrosive


Poisonous/toxic


Inert


Cryogenic


Pyrophoric(burns on contact with air)


or a combination of hazards

©Consultnet Limited

Introduction


Common Industrial Gases


Oxidants

support combustion e.g. air & oxygen


Inerts

do not generally react with other materials,
asphyxiants(leak displace air) e.g. nitrogen, argon,
helium


Flammables

when mixed with oxidant and ignition
source will burn e.g. acetylene, hydrogen, propane


Toxics

toxic in small concentrations e.g. ammonia,
chlorine, carbon dioxide


Corrosives

react with materials causing reactions
e.g. chlorine, sulfur dioxide


Pyrophorics

ignite spontaneously in air e.g. silane,
phosphine

©Consultnet Limited

Main Causes of Accidents


Inadequate training and supervision


Poor installation


Poor maintenance


Faulty equipment and/or design(e.g badly
fitting valves or regulators)


Poor handling


Poor storage


Inadequately ventilated working conditions

©Consultnet Limited

Main Hazards


Impact from the blast of a gas cylinder
explosion or rapid relase of compressed gas


Impact from parts of gas cylinders that fail
or any flying debris


Contact with the released gas or fluid(such
as chlorine)


Fire resulting from the escape of flammable
gas or fluids such as LPG


Impact from falling cylinder


©Consultnet Limited

Safe Working with Gas

Cylinder
s:

Identification and Properties


R
ead the label

to see what gas you are dealing with

and double
check tha the cylinder/gas is right for th eintended use


No compressed gas cylinder should be accepted for use that
does not legibly identify its contents by name


If the

labeling on a cylinder becomes unclear

or an attached tag
is defaced to the point the contents cannot be identified, the
cylinder should be marked "contents unknown" and

returned
directly to the manufacturer


Never rely on the color of the cylinder

for identification. Color
coding is not reliable because cylinder colors may vary with the
supplier. Additionally, labels on caps have little value because
caps are interchangeable


If there is a mismatch between the color of a cylinder and the
label. Do not use, contact the supplier immediately


K
now the properties

of the gas (read Material Safety Data Sheets

available from your Supervisor)


The cylinder’s
contents should be identified at all times

as well
as the cylinder status (full, empty or in service)

©Consultnet Limited

Safe Working with Gas

Cylinder
s

Work Practices


Securely restrain
cylinders to prevent them falling over


Close the cylinder valve
and replace dust caps when cylinder not in use


Before connecting a gas cylinder to equipment or pipework

make sure regulator and
pipework are suitable
for the gas and pressure being used


Never drop
a gas cylinder


N
ever tamper

with cylinders or subject them to abnormal mechanical shocks which
could damage the valve or safety device


N
ever
re
-
paint, change markings or identification or interfere with threads


N
ever
disguise damage to a cylinder or valve. Label as faulty and contact the supplier


N
ever
attempt to repair a cylinder


N
ever

scrap a cylinder


N
ever

subject cylinders to abnormally high or low temperatures


Never

mix gases in a cylinder


Never

try refill a cylinder


N
ever

transport by rolling them on the ground or use them as rollers or supports


N
ever

pick them up by magnetic lifting


Never

subject to abnormal mechanical shocks whuch could damage the valve or safety
device


©Consultnet Limited

Safe Working with Gas

Cylinder
s

Daily Inspection


Cylinders should be inspected daily
and prior to each use for corrosion,
leaks, cracks, etc.


Inspection should include the
cylinder, piping, safety relief
devices, valves, protection caps and
stems.


Leaking regulators, cylinder valves
or other equipment should be taken
out of service.


©Consultnet Limited

Safe Working with Gas

Cylinder
s


Maintenance of cylinders and their valves or relief devices shall be
performed only by trained personnel.


An emergency response plan shall be developed and implemented
wherever compressed gas cylinders are used, handled or stored.


Never smoke around compressed gas cylinders.


Valve protection caps must remain in place at all times except when
cylinders are secured and connected to dispensing equipment


Only wrenches or tools provided by the cylinder supplier should be
used to open or close a valve. At no time should pliers be used to
open a cylinder valve.


Never apply PTFE tape, jointing compounds or any other sealing
material to the valve in an attempt to achieve a tight seal, if a gas
tight seal cannot be achieved metal to metal, replace the regulator or
change the cylinder

©Consultnet Limited

After the regulator is attached, the cylinder
valve should be opened just enough to
indicate pressure on the regulator gauge (no
more than one full turn) and all the
connections checked with a soap solution for
leaks.

Never use oil or grease on the regulator of a
cylinder valve.



Before a regulator is removed from a cylinder, the cylinder valve shall

be closed and the regulator relieved of gas pressure.
The valve

cap shall be replaced, the cylinder clearly marked as "empty,"

and returned to a storage area for pickup by the supplier


Regulators, gauges, hoses and other apparatus shall not be used on

gas cylinders having different chemical properties


Valve outlet thread size is different for different products but the

same products from different gas suppliers will have the same

thread



Gas Cylinder Use

©Consultnet Limited

Gas Cylinder Regulators

A regulator is a device that receives gas at a high
pressure and reduces it to a much lower working
pressure


P
recision instruments and MUST be handled with care
to avoid damage to their sensitive springs, diaphragms,
valve seals etc.


E
quipment should display the relevant
European/British Standard number and the pressures
up to which it can operate


L
eave the pressure adjustment knob/screw fully out
when the regulator is not in use (this ensures a
minimum of tension on the springs and diaphragms)


Cylinders should be placed with the valve accessible at
all times. The main cylinder valve should be closed as
soon as it is no longer necessary that it be open, it
should never be left open when the equipment is
unattended or not operating


This is necessary not only for safety when the cylinder is
under pressure, but also to prevent the corrosion and
contamination resulting from diffusion of air and
moisture into the cylinder after it has been emptied.



©Consultnet Limited

Flashback Arrestors


Flashback is the result of mixture of fuel gas and oxygen
burning within the hose, flame travels and burns its way
towards the gas source at great speed, can result in force of
explosion in either cylinder


Flashback arrestors must be fitted on both oxygen and fuel
gas regulators


If flashback arrestor is dropped/damaged replace
immediately


Flashback arrestors should oinly be used with the gas they
are labelled for and the presuure thay are designed for


Coomon reasons for flashback: incorrect purging of
hose/torch prior to use, incorrect gas pressure, incorrect
nozzle, damaged torch valves, gas passages blocked within
the torch, kinked or trapped hose


©Consultnet Limited

Hoses


Correct hose bore size, pressure rating, length and color coding are essential
for safety BS EN 559


Blue


oxygen, Red
-

acetylene and other fuel gases(except LPG)


Black


inert and non combustible gases


Orange


Liquified Petroleum Gas


Never use hoses that are longer than necessary


Never use equipment while hoses are wrapped around the cylinders or trolley


Length of hose should be suitable for the task


Keep hoses in good condition


Examine the hose for cracks, deterioration, damage and test the hose for
leaks before use


Do not repair hoses unless you have the skill and means to test hem in
accordance with BS En 1256


Purge hose thoroughly before lighting torch


D
o not put wrapping tape around hosing as this contains combustible
hydrocarbons


D
o not use copper piping with acetylene hoses as it is potentially explosive


P
rotect hosing from heat, oil, grease or mechanical damage


©Consultnet Limited

Piping


Distribution lines and their outlets should be
clearly labeled as to the type of gas contained


Piping systems should be inspected for leaks on a
regular basis


Special attention should be given to fittings as well
as possible cracks that may have developed


©Consultnet Limited

Blow Pipes and Torches


Leaks are a serious hazard as they are closest to the operator


Always check condition before use, ensure tip is free of obstruction


Signs of heat damage around the blow pipe or torch may indicate the equipemnt
has sufferd interal damage and is leaking and should be replaced immeidately


No sign of sideways movement of the cutting leaver as this could cause gas
leaks within the body of the torch that are difficult to detect


Always fit the correct size nozzle for the job( hole size and pressure set at
regulator determine gas flow and gas velocity exiting the nozzle, manufacturer
gives a pressure rating for the nozzle being use, if the gas exit velocity is slower
than the combustion velocity backfire and flashback may occur


Replace blow pipe or torch if


Broken bent or loose gas control valve


Bent mixer, misshapen cutter head


Bent cutter tube


Broken of bent cutting oxygen lever


Leak test all connections and valves prior to use


If replacing O ring seals always use the correct materials

©Consultnet Limited

Acetylene

Unique properties


Acetylene gas under excess pressure becomes
unstable


Cylinders should never be subject to intense heat
or physical impact as the rise in temperature and
pressure may cause the acetylene to thermally
decompose


Prior to moving a cylinder that has been subject to
heat or severe impact contact trained emergency
personnel who can check for temperature rise and
apply correct procedures


The cylinder may appear normal but if it is moved
it may detonate with fatal consequences


©Consultnet Limited

Handling Gas Cylinders


Wear PPE: gloves, protective footwear, eye protection


Correct way to move cylinders is to:
keep upright, secure and with
valves uppermost


Use mechanical aids such as a trolley where reasonably practicable(
do a risk assessment)


Use suitable cradles, slings, clamps or other effective means when
lifting with a hoist or crane


F
or short distances on even ground the practice of ‘milk
-
churning’

(manually moving cylindres)

can be used
only
by trained personnel

and never
for longer distances,
in
uneven ground
,
wet or icy
conditions
, poor lighting, or at speed

a trolley should be used


All personnel involved should have completed manual handling
training


Never roll cylinders along the ground


Never transport cylinder with valve and pressure regulator attached
or with the valve open


N
ever attempt to catch a falling cylinder just get out of the way


Never lift a cylinder by its cap, valve or guard/shroud

R
emember that a cylinder is never empty

©Consultnet Limited

Transporting

Cylinders

Carriage of Dangerous Goods Regulations apply


I
f possible carry in open vehicles or trailers


I
f they must be carried in closed vans/cars ensure good
ventilation at all times


I
f the load compartment is not separated from the driver
do not carry toxic gas cylinders (those with a toxic gas
label and having yellow as a colour on the cylinder)


S
ecure cylinders properly so they cannot move

or fall

in
transit or do not project beyond the edges of the vehicle
,
normally in the upright position unless instructions for
transport state otherwise


Ensure gas cylinders are clearly labelled to show contents
and associated hazards


Fit suitable protective valve caps and covers to cylinders

©Consultnet Limited

Transporting

Cylinders

Carriage of Dangerous Goods Regulations apply


Disconnect hoses and regulators from cylinders


C
arry propane cylinders upright and do not
carry flammable gas cylinders in the same
compartment as toxic gas cylinders


D
o not smoke while carrying cylinders inside
vans/cars


U
nload the cylinders as soon as possible and
move to a well ventilated storage area


I
f you suspect it is leaking
,

park the vehicle,
investigate the fault and contact the supplier


I
f you are involved in an accident advise
,

any
emergency services involved what gas cylinders
are being carried

©Consultnet Limited


Safe Storage

Each Storage area should be subject to unique risk assessment


I
t is best to store gas cylinders in the open and on concrete in a fenced
compound with some weather protection


In

storage areas oxygen cylinders must be stored at least 3 metres
away/separated by a fire wall from fuel gases
such as

acetylene,
propane, methane etc.


F
ull cylinders should be stored separately from empties and empty
oxygen cylinders should be segregated from empty fuel gas cylinders


O
ther products should not be stored in the gas storage areas
especially not oil or corrosive liquids
, sources of ignition or flammable
materials


Ease of access into and around storage area, such as provision of aisle
>0.6m to prevent domino effect


LPG cylinders have special requirements including storage 3m away
from other gases


Pyrophoric and toxic gases should be stored seperately in locked,
suitable ventilated storage areas with restricted access


Protect gas cylinders from external heat sources which may adversely
affect their mechanical integrity


Cylinders should be secured and properly restrained,
secure with
straps or chains connected to a wall bracket or other fixed surface, or
by use of a cylinder stand


Cylinders should be clearly labelled to show contents and associated
hazards

©Consultnet Limited


Safe
S
torage


S
tore all cylinders upright and secure
on a level surface
to
prevent them from falling


A
cetylene and propane must never be stacked horizontally
either in storage or in use


S
torage arrangements should ensure turnaround of stock in
adequate time


S
torage areas with gas cylinders must have more than one exit


C
ylinders should be located away from any heat/source of
ignition and if possible away from the fire exit
s,
elevators,
walkways, building egresses, unprotected platform edges, or in
locations where heavy moving objects may strike or fall on them


Storage arrangements should be clearly described in the
emergency plan


Storage area must have good housekeeping and adequate
warning signs with fire fighting equipment as necessary

©Consultnet Limited

Cylinder

Incident Response

Report any damaged/leaking cylinder to supplier


I
f a cylinder

is
leaking

but the leak
has not ignited

and it
is safe to do

so

having considered the gases specific
properties
:


E
liminate all sources of ignition


E
nsure the valve is closed but do not over
-
tighten it


P
ut the cylinder in a safe place that is well
-
ventilated



keep it upright


M
ark the cylinder as faulty and not to be used


W
arn everyone in the area of the gas leak


I
nform the supplier


E
nsure the work area is thoroughly ventilated before
continuing with any work


If a hydrogen cylinder is involved be aware that
hydrogen burns with an invisible flame so seek expert
assistance

©Consultnet Limited

Cylinder

Incident Response

Report any damaged/leaking cylinder to supplier

If a
cylinder is leaking and it has ignited

it could
explode


C
all
the emergency services
and evacuate the
area to a minimum distance of 100 metres


Where a
cylinder has been damaged


I
f it has been dropped or physically damaged check it
for leakage and deal with as for a leaking cylinder


F
or handling acetylene cylinders
should not be moved
unless it is clearly established that there is no
thermal disassociation


C
learly mark any cylinder that has been exposed to
excessive heat or physical impact and contact the
supplier


©Consultnet Limited


Cylinder

Incident Response

If a
flashback has occurred
:


Close both blowpipe valves oxygen first


Close both cylinder valves


Check the temperature of the acetylene cylinder for
thermal decomposition


Check the blowpipe has not overheated


Check the nozzle is not damaged


Open both blowpipe valves oxygen first to vent the
system


Unwind the pressure adjustment screw on each
pressure regulator


Before starting up again, check the integrity of the
whole system

©Consultnet Limited

Cylinder

Incident Response

Gas Cylinders on Fire

Depends on the gas, whether the gas is alight at the cylinder
valve or if the cylinder has been subject to severe pressure as
a result of the heat from the fire. Nature of hazard will
determine procedure to be applied



If cylinder has been involved in fire do not approach, evacuate
the area to 100m minimium to 300m


Call fire brigade


Use large quantities of water to cool the cylinders if safe to do so
(do not aim high pressure water direct at the cylinders) from a
safe location and await the arrival of trained emergency
personnel (
Emergency plan training should address
)


Remove any cylinders not involved in fire to safe place, ensure
valves are closed if safe to do so


Inform gas supplier,


If cylinder contents are unknown, treat as acetylene



©Consultnet Limited

In Your Workplace


Look Out for Gas Cylinders:


In horizontol position/on the ground


In contact with electrical cords


Not protected from falling


chain not secure


Damaged


In an area where could be subject to impact such
as near operating forklift


Stored near combustibles


Oxygen and acetylene stored together


Without valve caps

Deal with these Hazards IMMEDIATELY

©Consultnet Limited

Conclusions


Compressed gases present a unique hazard. Depending on
the particular gas, there is a potential for simultaneous
exposure to both mechanical and chemical hazards


Inadequate training and supervision, poor installation, poor
maintenance, faulty equipment and/or design(e.g badly
fitting valves or regulators), poor handling, poor storage,
inadequately ventilated working conditions


When working with compressed gases you need to know the
properties of the gas, safe use procedures and what to do
when things go wrong


For detailed use of individual gases you should now review
the relevant Material Safety data Sheet (MSDS) for each gas
used on your site

Always Treat Gas Cylinders with Respect

For additional information which could be used as presentation handouts visit
UK
HSE information on
Gas Safety
for

a whole series of leaflets on the topic