WELDING
GAS WELDING
Cylinders
Combustible Gases - Left-hand Thread (anti-clockwise to tighten).
Non-combustible Gases - Right-hand Thread (clockwise to tighten).
To prevent the intercharge of fittings between cylinders containing combustible
and non-combustible gases, the valve outlets are threaded in opposite hands.
Combustible gases, ie Acetylene, hydrogen, propane and mixtures containing
fuel gas, all have left-hand threads.
Non-combustible gases ie Oxygen, nitrogen, argon and air all have conventional
right-hand threads.
Know Your Gases
Gas
Cylinder Colour
Oxygen
Nitrogen
Argon
Acetylene
Propane
Black
Grey with Black Neck
Blue
Maroon
Bright Red bearing words "Propane - Highly
Flammable"
Bright Red
Hydrogen
Transport
Remember cylinders are heavy - do not overload your vehicle.
Never roll a cylinder along the ground as it may damage the valve or the
identification marking.
When using cylinder trolleys, make sure the cylinders are located correctly,
secured and the valves are shut. Never transport cylinders with the regulators
and hoses attached unless on a purpose designed trolley or carrier.
Never lift a cylinder with magnets or chain slings. If a rope or man made fibre
sling is used lift only one cylinder at a time. Make sure the slings are positioned
correctly.
Revised Jan 2003
WELDING
Storing Your Cylinders Safely
Ideal storage: in the open but protected from corrosion.
It is best to store compressed gas cylinders in the open, in a security fenced
compound, but with some weather protection. cylinders should not be allowed to
stand directly on wet soil, as this will almost certainly cause corrosion.
Segregate oxygen from fuel gases: Full from empty
Within the storage area oxygen should be stored well away from the fuel gas
supply.
In addition, full cylinders should be stored separately from the empties and
empty cylinders which have contained different gases should also be segregated
from each other.
Do not use compressed gas stores for other products
You must not store other products in a gas store, particularly oils or corrosive
liquids.
Store all cylinders upright if possible. Always store acetylene and propane
upright.
It is best to store all cylinders upright, taking steps (particularly with roundbottomed cylinders) to see that they are secured to prevent them falling.
Acetylene and propane must never be stacked horizontally in storage or in use.
If any horizontal storage is used for other gases, the stack must be secured with
wedges and should not be more than three runs high.
Looking After Your Cylinders
Below are some of the recurrent causes of accidents involving compressed gas
cylinders. All are avoidable.
Heat - resulting in an increase in internal pressure. In extreme cases this could
weaken the cylinder wall and make it bulge or fail. Be careful with a lit oxy/ fuel
gas torch.
Gas Escape - gas from the cylinder valve or from an unlit blowpipe. This can
collect in a confined space and cause either a fire or a health hazard
Revised Jan 2003
WELDING
.
Leaks - through use of faulty apparatus or faulty assembly or the wrong parts.
Damage - careless handling, dropping or heavy impact.
There are a few elementary precautions.
Keep cylinder away from electrical welding tools and re-hot metal.
Do not allow electrical welding tools to touch or get near to cylinders. An
accidental arc between the tool and the cylinder could overheat the cylinder wall.
Take care not to allow welding and cutting sparks, flames or red-hot slag to
make contact with the cylinders, and keep them a safe distance from possible
accidental spillages of molten metal.
Never let oil or grease touch your cylinder or fittings.
Lubrication of any cylinder valves and fittings is unnecessary and highly
dangerous. So is the application of white or red lead, jointing compounds and
jointing tape.
Oxygen equipment is at most risk from oil and grease, so keep greasy hands,
rags and gloves away from any part of the cylinder and fittings.
Normal body oils do not usually matter though it is a sensible precaution never to
touch any surface which is subject to oxygen under pressure. High pressure
oxygen will react violently with oils or grease which may explode.
Keep cylinders and valves clean.
If grit, dirt, oil or dirty water get into the cylinder valve sockets, leakages may
occur.
Before assembling regulators and fittings make sure there are no particles or dirt
in the cylinder outlet.
Revised Jan 2003
WELDING
WORKING WITH CYLINDERS - MAKING SAFE CONNECTIONS
Valve Operation: Do not use force.
Open cylinder valve slowly.
An unopened valve should never be left against the backstop but should be
turned back at least 1/2 turn to let others know the valve is open.
When you shut it turn just enough to stop the gas completely. Never wrench it
shut. (Remember all cylinder valve spindles have conventional right-hand
threads, whether or not non-combustible gases).
Think of the cylinder valve as an electric switch. If you stop work for more than a
few moments, turn it off.
Non-standard keys.
Never use anything but the recommended cylinder valve keys. Never increase
the leverage of keys or use longer ones. Never use spanners with long handles;
or even the correct key if it is badly worn. All of these could easily damage the
valve seat or spindle square.
Look out for broken spindles.
If you think your cylinder valve has a broken or damaged spindle, do not use it.
Do not attempt to remove the gland nut, the broken spindle could be ejected or
unwound at great risk to the operator.
Always use equipment designed to take the gas pressure.
If you intend to use a piece of equipment designed to operate at a lower
pressure than that available from the cylinder, use a suitable pressure regulator,
fitted on each supply cylinder, or use a cylinder manifold which incorporates a
suitable regulator.
Do not rely solely on needle or fine adjustment valves, the hoses could be
subjected to near full cylinder pressure and rupture.
Revised Jan 2003
WELDING
Regulators: check the thread first.
Make sure the thread on regulators and other equipment are the same as those
in the valve outlets, 5/8 in BSP in most industrial gas equipment. Never force any
connection that does not fit.
Release the screw before fitting regulator.
Before fitting a regulator onto a full cylinder always zero the adjusting screw for
regulating the outlet pressure otherwise the regulator may be damaged.
No oil in any regulator - oxygen or not.
Never try to ease any regulator threads with oil even if it is not an oxygen
cylinder.
Hydrogen regulators: acetylene/propane regulators do not mix them.
Do not interchange left-hand threaded regulators. Each is designed for use with
a specific gas and to interchange them could be hazardous. Remember the
cylinder pressure and properties are different for each gas.
Does your manifold have the right regulators and flashback arrestors?
Where cylinders are connected to a manifold or header, this must be properly
designed and installed for the task by a specialist engineer. It must
be fitted
with one or more pressure regulators. if it is an acetylene manifold it must also
be fitted with an effective flashback arrestor.
Do not try to use compressed air equipment on oxygen.
some compressed air equipment has 1/2in BSP threaded connection on the
pipeline isolation valve outlet. It has occasionally happened that this connection
has been broken upstream of the hose connection, leaving the hose with a male
thread instead of a female. This 1/2in BSP male thread will marry up, after a
fashion, with a 5/8in BSP oxygen valve. By getting the thread to bind on the
bottom of the valve outlet, a tight mechanical joint, but almost certainly not a gas
tight joint, can be achieved. This practice is both unprofessional and dangerous
as most compressed air equipment is lubricated with opil, which with oxygen
may well explode.
Use a non-return valve with main gas.
If mains gas is used, the law is that a Gas Board approved non-return valve
must be fitted.
Revised Jan 2003
WELDING
WORKING WITH CYLINDERS - CHOOSING SAFE EQUIPMENT
Gauges: be guided by the gas supplier.
Use pressure gauges only in the ranges recommended by the gas supplier.
Gauges used to show the contents of oxygen, nitrogen or hydrogen cylinders,
should have a dial reading of not less than 316 bar. Oxygen gauges must have
the work "Oxygen" on them. Do not test them with oil. Gauges for acetylene
should have a maximum dial reading of 40 bar or more.
Hoses: use the right colour, the right quality.....
Use only blue BS 5120 standard hose for oxygen. Use only red BS standard
hose for acetylene. Use only orange BS standard hose for propane.
Inferior hoses harden and may later crack or leak or fire internally when subject
to oxygen.
.and the right end connection.
Use hoses with the ends firmly attached to nipples with loose nuts for connection
to regulator outlets and blowpipe inlets.
Never use old or second-hand clips for hose connections. Twisted wire can
cause serious injury if the hose works loose and flails about. Shoddy hose
connection is a frequent cause of accidents. Check connections regularly.
Every hose is safer with a hose check valve.
Flashbacks can and do occur, either through recommended pressures and
procedures not being observed for the nozzle being used, or nozzle blockages.
One of the main causes of flashbacks is due to backfeeding which occurs when
higher pressure gas feeds back up a lower pressure stream, the pressure of
Saffire hose check valves will prevent the oxygen and fuel gas mixing in the
hose and subsequently causing fire, injury and damage.
Hose checks valves, it must be stressed, are a safeguard in an emergency, not
a passport to careless pressure control.
Flashback Arrestors.
A flashback arrestor is a device designed to quench the flashback and, when it
incorporates a cut off valve, will automatically shut the gas flow. Thereby
affording an additional safeguard.
Revised Jan 2003
WELDING
Do not use longer hoses than necessary.
It is bad practice to use lengths of hoses longer than necessary, especially when
it involves coupling more that one standard length together. If a long hose
assembly is necessary on the occasional job, use only recommended couplings
and dismantle them when the job is complete.
Do not use hoses that look worn.
Although hoses can be salvaged after accidental surface damage or end-wear
by cutting away the damaged section, always discard hoses when their general
condition shows signs of deterioration. In any event do not use more than three
couplers per five metres of hose.
Use correct personal safety wear.
Use goggles with double lenses of the approved tints (preferably to BS 679) to
protect eyes from sparks and glare. The clear outer lenses should be changed
regularly when spatter builds up.
Do not wear clothes made of highly combustible materials. Leather gloves of
gauntlets should be used when necessary and in awkward work locations,
additional protective clothing may be required.
KEEPING YOUR EQUIPMENT SAFE
Regularly check for faults and leaks.
Pay special attention to gauges. A defective gauge should be replaced
immediately.
As a matter of routine, always check for leaks when the equipment is
assembled. A solution of 0.5% Tepol in water applied to the joint with a
brush will reveal any leaks.If there is any frothing, the system should be
immediately depressurised and the leak corrected.
Faulty or leaking equipment should be returned to a reputable service centre for
repair. Do not attempt to carry out repairs yourself.
Do not use hoses coiled.
Ensure that both hoses are of equal length and do not coil surplus hose around
the cylinder or regulator. A fire in a coiled hose is very difficult to extinguish. If
you do have a surplus of hose, position it behind you to keep it clear of sparks.
Revised Jan 2003
WELDING
KEEPING YOUR ENVIRONMENT SAFE
All cylinder gases need good ventilation
Wherever cylinder gases are used you should maintain constant and thorough
ventilation. This is particularly important when they are used in confined spaces.
Oxygen enrichment, know the danger
The normal oxygen content of air is 21%. If this becomes enriched to 25% there
is an observable increase in the speed at which materials will burn. At 30% the
typical characteristics of an oxygen-fed fire are apparent. The fire is in two
phases - an initial flash fire followed by local burning at a number of points. Fires
in oxygen- enriched atmospheres are very difficult to extinguish and can spread
rapidly across combustible material from a single-point source such as a spark
from a cigarette. Fire will not, however, travel through the enriched air itself.
AND ALL CAUSES
Leakage from vessels. Vessels normally using oxygen in a process may
become enriched if the isolating valve leaks and the oxygen supply is not
properly isolated by a physical gap or by the insertion of blank flanges.
Leakage from equipment. Do not leave oxygen equipment in a confined space
when it is not being used. When it is in use, someone who understands the
equipment should be stationed outside to control the gas supply and give the
operator any assistance.
Deliberate enrichment. Never use oxygen to "sweeten" atmosphere or to
remove smoke or fumes.
There are other ways in which excessive oxygen can be released into the
atmosphere. You should be constantly alert to any potentially dangerous practice
in your workshop.
Even inert gases can kill.
Nitrogen, argon, carbon dioxide and fuel gases if allowed to replace the oxygen
in the atmosphere can cause asphyxiation. The dangers occur typically when
gas is released in confined space. nitrogen is often deliberately used to displace
oxygen, eg in blanketing operations, and personnel should take care not to
subject themselves to such an atmosphere.
Revised Jan 2003
WELDING
Oxygen depleted atmospheres are often difficult to identify, since danger
areas may be highly localised, for instance in a small tank where a heavy
gas
has collected in the base. An operator working in such a tank may not
realise this
hazard and he bends down and becomes asphyxiated.
Anyone who has been asphyxiated should be given pure oxygen without delay
using a suitable resuscitator .
As with oxygen equipment, never leave any gas equipment in a confined space
when not being used.
Take action against fume.....
Fume hazards can occasionally exist in some flame processes and conditions,
such as:
1.
2.
Paint burning.
Galvanised plate welding.
In all flame work ensure proper ventilation including extraction at the
point of work and/or the wearing of approved respirators if necessary.
If an operator feels the effect of fumes he must tell his supervisor
immediately and medical advice should be sought.
Leaks
As a matter of routine always check for leaks, test with a solution of 1/2% Tepol
in water and brush. Never use a naked flame to trace leaks. In hoses, leakages,
cuts or local surface damage may be repaired by cutting out the faulty section
and inserting an approved coupling. Worn ends should be cut back and re-fitted
with the appropriate hose connections and clips. Discard hoses that show signs
of general deterioration.
Flashback or sudden distinguishing of flame
1.
2.
3.
4.
5.
6
Shut both blowpipe valves, closing oxygen first.
Check that regulator settings were correct.
Check cylinder pressures.
If blowpipe is overheated plunge it in cold water, afterwards making sure
that the nozzle is tight.
Purge both hoses individually.
Relight after making certain that the fuel gas flow has become properly
established.
Revised Jan 2003
WELDING
Usually this occurs with excessive flow rates for equipment being used.
Consult manufacturers regarding correct equipment.
Frozen regulators or valves
Thaw with hot water, never by flame.
Frozen cylinders
Can be overcome by manifolding cylinders - do not heat the cylinders.
IF SOMETHING GOES WRONG
Hot acetylene cylinder
If an acetylene cylinder is heated accidentally or becomes hot due to flashback, it
must be dealt with promptly as follows:
1.
2.
3.
4.
5.
6.
Shut valve
Detach regulator or other fitting.
Take cylinder out of doors and immerse or drench in cold water until
cylinder is cool (ie until it remains wet when water treatment is stopped.
This may take several hours.)
Meanwhile contact the suppliers for further advice.
If cylinder is too hot to touch continuously, do not move it but drench with
cold water.
Call the fire brigade.
If acetylene leaks
If an acetylene valve shows a minor leak and it cannot be stopped by closing the
valve or tightening the gland nut, move the cylinder outside to a safe area and
contact your supplier. Take the same action if a safety device shows a small
leak.
Heated LPG cylinder
Leaking but not on fire.
1.
2.
If possible stop leak by shutting off valve.
If not possible to stop leak, remove to a safe outdoor position, keeping the
leak uppermost.
Revised Jan 2003
WELDING
Leaking cylinder on fire.
1.
2.
If you suspect the valve is damaged, call th fire brigade. Do not attempt to
extinguish the fire yourself.
If the valve is undamaged, close it, using a fire extinguisher as necessary.
Cylinder exposed to a heat source, such as a general fire.
1.
Keep the cylinder cool with water and remove from heat source if
possible.
Heated hydrogen cylinder
If hydrogen cylinders are accidentally heated through the use of faulty equipment
or operation:
1.
2.
Use a fire extinguisher. Take care as there is little radiant heat from a
hydrogen fire to warn you that there is a flame.
Close valve as soon as possible.
Heated cylinders containing other gases
Take action to eliminate the fire so as to prevent the pressure vessel being
destroyed through excessive heating.
.....Fire.....
Never underestimate the fire hazard in flame processes particularly as sparks
can travel an appreciable distance.
1.
2.
3.
4.
5.
6.
Where possible work well away from flammable materials such as wood.
Remove all materials likely to catch fire.
Make sure the floor is swept clear of flammable debris or dust.
Avoid work on wooden floors or close to wooden roof joists, without using
protection such as sheet steel or other non-combustible materials. Sparks
falling through gaps in floorboards are a particular source of danger.
Keep fire extinguishers sand and water available. If necessary douse
floors and walls with water before starting work.
If you suspect that sparks may have come in contact with wooden
structures or entered wall cavities, special precautions should be taken
after the work has finished. Remember that fire can smoulder for long
periods before erupting.
Revised Jan 2003
WELDING
ELECTRIC ARC WELDING
Typical welding circuits
Power
source
Connector
Workpiece
Workpiece
earth
This shows the principle of the welding circuit.
1.
The isolation switch for the mains supply to welding transformer.
2.
A double wound step down transformer which may incorporate the welding
current regulator.
3.
Welding lead which carries the current to the electrode holder.
4.
The electrode holder.
5.
.
6.
The return lead which completes the circuit to the welding transformer
The "earthed" workpiece.
7.
The earth connection to the welding transformer enclosure which usually is the
protective conductor in the mains supply cable.
8.
Welding cable connectors.
The use of manual electric arc welding brings the operators close to the
electrode and workpiece enabling electric shock or being burned by the arc or
hot metal possible. Electric shock may also be encountered by the operator
when changing the electrodes or when carrying out work in awkward situations.
Accident statistics have shown that electric shocks have been sustained from
poorly installed or maintained equipment or through bad working practices or
carelessness. In ensuring safety of operators all arc welding equipment should
be well designed and constructed and properly designed and constructed and
properly maintained and safe working practices followed.
Revised Jan 2003
WELDING
The most likely risk of electric shock is from contact with bare live parts of the
welding circuit. Voltages across the arc may only be 20 to 40 volts, the open
circuit no-load voltage must be higher to enable the arc to be struck in the first
place. The maximum open circuit no-load voltages recommended in the British
Standard 638 are 80 volts ac and 100 volts dc. Direct current systems with more
than 10% ripple (rms) are considered to be as hazardous as ac systems of the
same voltage.
These voltages may appear low as compared with the 240 volts ac main supply.
However, it is shown that only voltages below 50 volts ac or 120 volts dc are
unlikely to be dangerous to healthy people in dry roomy conditions. In confined
conducting location or wet surroundings potentials of 80 volts ac have been the
cause of fatal electric shocks.
Other electric shocks can arise from:
a)
The potential existing between electrode holders connected to different phases
of a three-phase welding transformer or between electrode holders supplied from
single phase transformers connected to different phases of a three-phase mains
supply or between electrode holders supplied from cross-connected singlephase welding transformers;
b)
The possibility of mains voltage being impressed on the welding circuit due to
insulation failure of the welding transformer.
A different kind of hazard may be caused by stray welding currents, which return
to the welding transformer by paths other than the welding return lead:
a)
The earthed protective conductors of electrical equipment in the vicinity. The
stray currents can damage or burn out these protective conductors, thereby
destroying the integrity of the equipment earths;
b)
Wire ropes, slings and chains which may be damaged by overheating and fail in
service;
c)
Metal fittings and pipework, in particular services such as air, gas, water,
lubrication, steam or hydraulic pipework which would be damaged.
In one unusual case, stray welding current flowed through part of the water
cooled secondary winding of an arc furnace transformer, energising the
disconnected primary winding terminals at a sufficiently high voltage to cause an
electrocution.
Revised Jan 2003
WELDING
Stray currents, which may be of considerable magnitude, comparable with the
welding current itself, result from:
a)
Poor or faulty insulation of the welding return lead which may thus be short
circuited or by-passed by other conductors with which it may come into contact;
b)
Not placing the welding return lead as close as possible to the point where the
welding is to be done, in particular on building structures and pipework
installations. The only exception to this is where a metallic grid, support structure
or the metal hull of a ship is intentionally used as part of the welding return
circuit;
Incorrect earthing of the welding circuit.
c)
PRECAUTIONS
Equipment
Appropriate protective clothing ie gloves, boots, overalls, aprons and eye
protection will protect operatives from electric shocks and burns to some extent;
adequate protective clothing is particularly important when the job is in a
confined conductive space, to minimise the area of bare skin that can make
contact with the surroundings.
Welding equipment should conform to the appropriate parts of BS 638. Electrode
holders that offer maximum protection against electric shock are recommended.
These are usually insulated throughout, so that there is no bare metal that can
be inadvertently touched other than the electrode itself. Electrode holders should
be suitably shaped to avoid damage to the cable insulation where the cable
enters the holder and is subject to bending when the holder is in use.
Welding leads and return leads should be insulated, of robust construction and
big enough to carry the welding current safely. Welding lead connections should
be suitably insulated, and should not expose live conductors when the parts of
the connector are separated.
Earthing the workpiece is important. The workpiece and any metalwork in
contact with it should be at the same potential as the surroundings. The purpose
of earthing is to provide protection against internal insulation failure of the
welding transformer, by keeping the workpiece at or near earth potential until the
protective device (eg a fuse) operates to cut off the mains supply. The workpiece
earthing conductor should be robust enough to withstand possible mechanical
damage and connected to the workpiece and a suitable earth terminal by bolted
lugs or secure screw clamps.
Revised Jan 2003
WELDING
Self contained engine driven welding sets may be used without a workpiece
earth. In the case of these units, there is no source that can impress a higher
voltage on the welding circuit or workpiece under internal fault conditions.
Welding regulators and transformers should comply with BS 638. In most
circumstances, metallic enclosures of a regulator will be in contact with the
ground or a metallic structure where they will be fortuitously earthed. It is
recommended that regulator enclosures should be intentionally earthed by a
suitable earth connection, as in the case of the workpiece and should not rely on
fortuitous earthing via the regulator case and the ground or metallic structure.
Welding installations should have an efficient and convenient means of switching
off the power supply, eg a readily accessible mains switch near the welding
transformer. The tank or metallic enclosure of the welding transformer should be
earthed either via the protective conductor in the mains supply cable or
independently. For small units a flexible cable with a braided screen and PVC
oversheath is recommended. The supply fuses or any other device protecting
the mains supply circuit should be suitably rated for the purpose.
If the circumstances of use or the system of work cannot be relied upon to
ensure that a welding transformer, mains powered rectifier unit or motor
generator is satisfactorily earthed at all times when in use, you should consider
supplementary protective devices. The simplest of these is a residual current
earth leakage circuit breaker included in the mains supply. If necessary an earth
monitoring unit may be installed at the supply point to check the presence and
integrity of the earthing system before mains power can be switched on.
Working Practices.
Welding operatives should remove personal jewellery, in particular rings and
bracelets and metallic watch straps, before starting work. In one instance a
welding operator's finger was badly damaged when transformer action from an
adjacent welding lead induced currents in a ring the operative was wearing and
partially melted it.
Revised Jan 2003
WELDING
There should be some means at the workplace of making an electrode
holder dead so that electrodes can be replaced safely. This is easily achieved if
the welding lead is connected to the electrode holder by a plug and socket connector,
with the shrouded portion on the welding
lead.Otherwise a
similarly arranged shrouded cable coupler should be
inserted in the welding lead at a convenient point. You should not rely on the
insulation of gloves to protect you if you try to change electrodes, with the
holder live. DO NOT hold live electrodes
under the armpit, which is likely to
be moist.
If you stop welding for a short time, be careful where you put down the electrode
holder. DO NOT put it on a face shield, clothing or rags. An insulated container
or an insulated hook is recommended. When you have finished welding, remove
the electrode from its holder, which has been made dead by disconnection from
the welding lead, and switch off the power supply.
If three-phase welding circuits or single phase circuits derived from different
phases of the mains supply are used, the welding positions connected to
different phases or transformers should be segregated, so far as is reasonably
practical. this reduces the possibility of electric shock resulting from
simultaneous contact with any parts of two different systems, irrespective of the
voltage of either one to earth.
When it is necessary to weld in confined spaces the following precautions
should be observed:
a)
b)
c)
d)
e)
wear the necessary protective clothing, including insulating safety boots;
stand or kneel on a mat or stand made from insulating material which should be
kept dry;
use only an all-insulated holder to offer the maximum protection from electric
shock;
place the welding transformer and regulator outside the working space;
someone should be in attendance, immediately outside the working space,
trained in first aid, including artificial respiration for anyone suffering electric
shock, who can switch off the electrical supply and give assistance should it be
necessary.
Dc welding is safer than ac welding in confined conductive locations and should
be used if possible. If ac welding is used, the open circuit no-load voltage should
be limited, where reasonably practicable, by a voltage reduction device. These
devices, on which manufactures can give further advice, limit the open circuit noload voltage to about 40V until the electrode contacts the workpiece.
Revised Jan 2003
WELDING
Large structures or vessels which are welded when supported on
manipulating rollers or similar devices require special attention to ensure the
integrity of the welding return current connections and the earthing.
It may be necessary in some cases to pre-heat the structure or vessel being
welded with metal sheathed heating elements.
Fire Precautions
Good housekeeping in the working area, alertness and suitable fire
extinguishers, readily available, will reduce the risk of fire from welding
equipment or the welding process.
Training/Information
Manufacturers instructions for the use of welding equipment should be available
to operators if necessary. All operators should be trained in the safe use of
equipment.
Operators and anyone working in the vicinity should be warned of the possible
hazards and informed about the precautions which are required to prevent injury
or accidents.
Inspection and Maintenance
All operators should be instructed to visually check equipment for any obvious
defects before use, reporting any found.
Arrangements should be made for regular, thorough examination of equipment
throughout its service. defects found should be repaired promptly. In respect of
these arrangements, it is wise if written records are kept so as future reference
can be made.
Revised Jan 2003