MECHANICAL HANDLING:
Mechanical handling covers lifting, transporting, and
placing the heavy components at desired location. For
handling heavy items or machinery, various types of lifting machines with lifting
tackles are used.
·
LIFTING
MACHINES:
a.
ELECTRIC
OPERATED OVERHEAD TRAVELING CRANE
b.
MOBILE
CRANE
i.
Tyre-mounted
crane
ii.
Crawler cranes
c.
FORKLIFTS
d.
LIFT
AND HOIST
LIFT AND HOIST:
Lifts are used to transport persons (humans)
vertically i.e. to raise or lower whereas hoist is
used to transport or shift
material vertically. As lift is used to lift persons, it should be needs
more safe than the hoist.
Safe Design considerations:
o
Competent
person should test and inspect it.
o
All
hoist ways, moving parts should be properly protected by enclosure, fittings,
gates etc.
o
Cage
of should be fitted with gate.
o
Every
gate must have interlocking arrangement.
o
There
should be at least two ropes separately for lift and counter weight.
o
There
should be efficient automatic device to prevent overturning.
o
There
should be efficient automatic device to prevent over speeding i.e governor.
o
Electrical
equipments of lift should be properly earth.
o
Counterweights
should run in guides.
o
Lift
should have mechanical friction brakes, if the rope fails.
o The
minimum of two turns of rope shall remain on the drums when cage is at its
bottom position.
o There
should be shock absorbers at the bottom of lift shaft. ll lifts should have
fire alarm and emergency alarm.
FORKLIFTS:
A forklift is a
very versatile machine for handling the material and for shifting and stacking
of material. These are also called counter balance trucks. The forks are load
tested at 3 times the rated load of forklift without shock.
The
following precaution should be taken, when using forklift:-
·
Do
not operate a forklift unless authorized to do so.
·
Check
fuel level, leakages in fuel line and hydraulic system.
·
Check
battery connection and liquid level.
·
Check
brakes, steering, horn etc.
·
Safe
working load should be marked on forklift.
·
Do
not drive at higher speed.
·
When
driving with load on slope, ensure center of gravity of the load should fall on
the vehicle.
·
Keep
the fork about 10-15cm above the ground while driving.
·
Always
keep the top level of load below eye level.
·
Adjust
the fork to match the width of the load.
·
Ensure
the load should butt the mast while moving.
·
Never
carry passengers.
·
Never
raise or lower the load while in motion.
SAFETY
PRECAUTION IN CRANE OPERATION:
·
Crane
should be operated by authorized person only.
·
Lifting
and shifting of any person is strictly prohibited.
· While
operating, vertical or lateral distance between part of crane and any overhead
power cable must not less than 6meter.
·
Ensure
the passage is free from obstruction.
·
Do
not move hook when it is out of sight, unless directed by group leader.
·
A
clear space of 18” must be maintained between any moving part of crane and any
stationary part or object.
· Operator
must keep constant watch on the safe working load indicator. He should check
the load and the operating radius.
·
Always
work on firm leveled ground.
·
Only
one authorized person should give signal.
·
Set
all out Riggs firmly.
·
The
operator should not leave control cabin when load is in suspended condition.
·
Check
all loads are properly hooked, before they are picked up.
·
Operator’s
cabin glass should be kept clean for good visibility.
·
All
brakes should be checked before lifting operation.
·
Never
drag the load as it may swing and hit to riggers or nearby object.
·
Before
unhooked, all loads must be safely landed and secured properly.
·
Before
starting crane, operator must take daily checkups.
·
If
crane is idle for a period of over six months, a complete inspection is
mandatory.
CRANE TESTING:
(once in a year )
DEFLECTION
TEST (FOR EOT Crane only & at SWL)
The downward
deflection of both beams, between no-load and full-load condition of the crane,
the deflection should not be more than-
Total span of
beam (in mm)
------------------------------------
900
OVERLOAD
TEST :
For testing the
crane on Over Load, according to Rule No. 36 of Atomic Energy Factories
Rule,
the test load shall be selected using the following table:
Safe working load Test load
-----------------------
---------------
Up to 20 tons 25 % in excess
20 to 50 tons 5
tons in excess
More than 50 tons
10 % in excess
Cross travels,
Long travel and Hoist movement on Over Load shall be checked.
TESTING
OF TACKLES
:- (chain,
shackles, chain blocks etc.)
At
1.5 times the S.W.L.
LIFTING TACKLES :
a.
FIBRE
ROPES
b.
WIRE
ROPES AND SLINGS
c.
CHAINS
AND CHAIN SLINGS
d.
SHACKLES
e.
EYEBOLTS
FIBRE ROPES:
·
The
fibre ropes are used to handle comparatively lighter weights.
·
It
should be made of sound material, is of good construction and have adequate
strength.
·
Proper
storing is very important. Store the fibre rope in cool dry room in hanging
loose coiled on pegs.
·
Select
proper rope for use.
·
Inspect
the rope before use.
·
Keep
ropes clean and dry.
·
Use
ropes away from heat, fumes and chemicals.
·
Never
overload ropes.
·
Avoid
using ropes against sharp edges protect them by padding.
·
Check
for friction heat while using synthetic ropes.
WIRE ROPES AND
SLINGS :
·
Wire
rope should have safety factor of 7 when carrying material and 10 when carrying
personnel.
·
Before
putting into service wire ropes should be examined to see that they meet all
requirements of load conditions.
·
Wire
ropes and slings, which have not been in use for 3 months or more and exposed
to water should be inspected for corrosion.
BROKEN
WIRE- Wire rope or
sling should be discarded if –
·
6
or more wires are broken in one lay
·
3
or more broken wires in one strand in one lay.
·
In
any length of the 8 diameters, the no. of visible broken wire exceed 10% of the
total wires
WORN AND ABRADED WIRES-If the wear on outer wires exceeds 1/3rd of the original diameter of the wire, rope or sluing is to be replaced
REDUCTION IN ROPE DIAMETER-Approximately a reduction in diameter of 6% should be cause for replacement.
ROPE STRETCH- If rope length is increased 150mm or more per 30meter length, rope should be replaced.
BIRD CAGE- Wire rope or slings having bird caging caused by sudden release of tension should be discarded.
KINK-It is caused by bending of rope, these rope losses its strength. Thus it should be discarded.
LUBRICATION- Dry wire ropes should not be used.
Precautions In
Using Wire Rope And Slings:-
·
Use
correct size according to the load handled.
·
Safe
working load should be marked on it.
·
Protect
slings from sharp corners.
·
Rope/sling
should not rub with any surface.
·
Thimbles
should be available on eyes of slings.
·
Avoid
dropping rope from height.
·
Prevent
loops in as this would cause kinking.
·
Lubricate
regularly as per recommendation.
·
If
using two or more slings consider reduction factor at included angle.
· Equalize
loading on multiple leg sling.
The
following practices should be adopted to prevent chain failure:-
·
Store
chain in suitable environment.
·
Never
put a strain on kinked chain.
·
Avoid
sudden loading i.e. jerk.
·
Never
drop a chain from height.
·
Never
splice a chain by inserting a bolt or other material piece between the links.
SHACKLES:
·
Shackles
are used to join fitting to slings.
·
Two
common types of shackles are
(1) D- shackle (2) Bow-shackle.
·
Shackles
are to be tested at 2times of the SWL.
The following
inspection is to be done on shackles before use:-
·
Check
the pin for wear (max. allowable 10%
·
Check
the crown for wear (max. allowable 10% )
·
Pin
should be properly seated.
·
Check
that the mouth is not opened up.
·
Never
allow shackle to be pulled at an angle.
·
Safe
working load should be clearly marked on it.
·
Never
use normal bolt as a pin.
EYEBOLTS: Eyebolts are used to provide facility of attachment of
slings, chains etc. to the equipment for handling purpose.
Precaution while
using eyebolt is as follows:-
·
Pull
should always be in line with shank.
·
Collarless
eyebolts are designed for vertical loads only.
·
Ensure
that bolt is tightened and torque is sufficient.
·
Ensure
that collar is firmly in contact with surface
·
Never
drop eyebolt from height.
·
Never
run a sling through a pair of eyebolt.
SAFETY IN WELDING PROCESS:
The hazards in
the welding process are:
·
Electric
shock
·
Infra
red and ultra violet radiations
·
Metal
fumes and hazardous gases
·
Fire
SAFETY
PRECAUTION IN ARC WELDING PROCESS:
The welder should always keep his body insulated
from both the work and the metal electrode and holder.
- He should always wear shoes and gloves.
- Use well-insulated electrode holders with well-insulated jaws
- Cables must be well insulated.
- Working area must be dry. Any water in the area must be cleaned before starting the job.
- Do not see arc with naked eyes, always use welding helmet.
- Always wear thick overall for protection against infra-red rays.
- Area should be well ventilated to avoid inhalation of metal fumes & other toxic gases.
- Safe distance is to be maintained from flammable material or safe guarding by covering asbestos cloth or metal sheet is to be done
- The welding cables must be in good conditions.
- Where it is necessary to couple several lengths together, the cable& connectors should be insulated on both the ground line and the electrode holder line.
- The welding cable should not cause a stumbling hazard.
- Don't operate welding machine without a proper ground.
- Before commencing the welding operations the location should be checked for any possible fire hazard.
- Welding operations should not be permitted in or near rooms containing flammable vapors, liquids or dust or in closed tanks or other containers which have held flammable liquids, until all fire and explosion hazards have been eliminated
- If welding is performed in confined spaces some means should be provided for quickly removing the person in case of emergency.
- After welding, chalk mark the 'HOT' metal or provide some warning sign to prevent their workers from coming into contact with the parts just welded
- Personal protective equipments should be used during the welding process.
SAFETY
IN GAS CUTTING:
PRECAUTION IN
GAS CUTTING
o
Select
the proper tip or cutting nozzle and screw carefully but not too tightly on the
torch.
o
When
changing torches, shut off gases at pressure regulators and not by crimping the
hose.
o
The
cutting torch should be lighted with a friction lighter. Matches should never
be used
o
When the cutting is finished, extinguish the
flame by closing the acetylene valve first and
then oxygen valve.
o
When the cutting is stopped for a longer
period, close the cylinder valves
o
Don't
leave unlighted torches connected for use in confined spaces during lunch hour
or when leaving work for other reasons.
o
Accumulation
of slag on the blow-pipe-tip should be frequently removed by using hard wood
sticks or soft brass wire to avoid flash back or back fire.
o
Hoses
of different colors should always be used for different gases. Red is the
generally recognized color to be used for acetylene and other fuel gases and
green or black for oxygen. Do not interchange the hoses.
o
Protect
the hose from flying sparks, hot slag and hot objects.
o
Do
not allow hose to come into contact with oil or grease.
o
Make
sure that the threads on the regulators and other auxiliary equipment are the
same as those on cylinder valve outlets. Right hand for oxygen and
non-combustible gases. Left hand for acetylene, Hydrogen and combustible gases.
o
Do
not use cutting equipment near spray painting rooms.
o
Always
keep cylinders up-right.
o
Use
flash back arrestor.
o
Discard
hose, if back fire occurs.