Construction Acc

8/8/2019 Construction Acc

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WORKING AT DIFFERENTLEVELS

byS. A. Solanki

Deputy Director

Industrial Safety & Health (Retd.)


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WORKING AT HEIGHT

Most of fall accidents happen while

working at height and most of them prove

fatal. Therefore seriousness of fall

accidents should be considered seriously.Fall accidents contribute at 10 to 20% total

fatal and 15 to 80% non-fatal accidents.


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Types, Cases and Control of Fall Accidents

Falls and accidents due to falling objects can

be classified as under:

(A) Falls of Persons:

Falls from heights viz. structure, floor,

ladder, scaffold, platform.Falls into depth (negative height) viz.

wells, pit, sump, silos, ground, tank,

vessel, excavation, ditches.

Falls on the same level viz. falling or

slipping on the floor or flat at the standing

level.


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(B) Falling Objects (bodies):

Falls of objects from height viz. tools,

machine part, equipment, material. Falls of objects from the hands of the

same person viz. tool, equipment,material being handled.

Structural collapse viz. wall, buildingceiling, pipe, ladder, scaffold, beam,truss.

Material collapse viz. falling of piles of

goods, layers of begs, cloth, paper rolls,carton boxes, grain, cement andfertilizer:

Slides and cave-ins viz. earth, rock, sand,stones, snow, ice.


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Most serious accidents due to falls and

struck by falling bodies take place in miningand quarrying, building and construction,

structural repair, alteration, cleaning,

painting, demolition, maintenance and

unsafe use of lifting and other equipment. Major causes of such accidents are

makeshift arrangement, unsafe floor, unsafe

work practices, not using helmet, safety belt,

safety shoes, unsafe use of vehicles, poorsupervision, poor lighting etc.


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Common Causes of Falls are:

Water, oil or grease not cleaned up.

Loose, defective broken floor or tow

board.

Scrap, chipping, swat and obstructions

lying on the way. Dusty, steamy or smoky atmosphere

restricting vision.

Carrying too much load making it difficult

to see over the load.

Warn out or unsuitable footwear.

Poor lighting, glare or shadows.


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Rushing instead of walking.

Defective or weak scaffolds.

Ladders, ramps, planks and platformsnot rigid or safe for the job.

No or inadequate handrails.

Climbing oddly instead of using ladder.

Throwing instead of lowering tools ormaterials while working aloft.

Not using spectacles for clear vision.

Not using crawling board on fragile roof.

Not using a safety belt or using in awrong way, e.g. not tying its free-end ortying it with a weak support.


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Not closing the manhole cover or floor-

opening etc.

Allowing roof work and floor work at a

time in the same vertical plane.

Touching of crane boom, hook etc. to

weak or unfastened structure. Non-compliance of statutory provisions.

Most of the falls from height prove fatal

or result in serious fracture. Therefore

their prevention or control is utmost

necessary.


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Control Measures for Fall Accidents:

Safe, sound and dry (non-slippery)surfaces for walking and working.Fencing, guarding and tow boards.

Safe helmet, safety belt, foot-wear, etc.

Safe practice in walking and working. Noexcessive load lifting.

Safe means of access while working atheight or depth.

Use of crawling board, cat ladder, fallarrester net etc. while working on fragileroof.


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Use of Safety work permit for working at

height or in depth. Safe and sound stairs, ladders, scaffold

etc. and safe use thereof.

Good lighting and supervision, cutting

off power supply in overhead electriclines.

Safety cordon to disallow persons in the

area where any object may fall from

height.

Removal of 20 causes mentioned above.


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Statutory Provisions

Section 32 and 33 of the Factories Act, 1948

provide precautions regarding floors, stairs,means of access, pits, sumps, openings infloor etc. Accordingly all floors, steps, stairs,passages and gangways should be of soundconstruction, properly maintained and keptfree from obstructions and substances likelyto cause persons to slip. Steps, stairs,passages, gangways with substantialhandrails, fencing and safe means of access toevery work place, shall be provided to preventa fall and ensure safety.

Every fixed vessel, sump, tank, pit oropening in the ground or in the floor whosedepth, situation, construction or contents aredangerous should be securely covered orfenced.


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Rule 68 describes the ladder quality that it

should have hooks or an effective non-skiddevice.

Rule 68E, GFR, provides for suitable andsufficient ladders, duck ladders or crawling

boards and a permit to work system whileworking on fragile roofs at a heightexceeding 3 mt.

Schedule 19 and other Schedules u/r 102 of

the Gujarat Factories Rules prescribe rules,for working at height and depth.


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Section 36 prescribes details of entering any

confined space. Before such entry, the space

is to be made free of dangerous fume, gas,vapour or dust. Work permit system should

be followed and a suitable breathing

apparatus and safety belt to be used by the

person. Section 36 A require a portable electric light

up to 24 V and a flameproof lamp for

flammable atmosphere.

Dimension of manholes, under rule 64 of the

Gujarat Factories Rules are given as circular

41 cm diameter or rectangular 41 cm x 31 cm.


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Safety requirement while working at Height

Falls happen due to falling from stairways,

runs, ramps, gangways, floors and ladders.

Therefore safety aspects of their design,construction and use are explained below:


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Stairways:

The slope of a stairway should be 300 to 350

with the horizontal. The tread width shouldnot be less than 24 cm plus a non-slipnosing of 2.5 cm. the riser height shouldnot be more than 20 cm and not less than12.75 cm and should be constant for each

flight. All stairways should be fitted withrailings on the open sides and hand rails onsides which are otherwise enclosed. Theheight of the railings at the stairs should benot less than 75 cm or more than 90 cm

measured from the top surface of the stairtread. The stair landings should beprotected by railings and toe-boards. Non-skid strips on stair treads can preventslipping.


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Adequate lighting on stairway should be provided to

avoid accidents. Two formulate are quoted in ILO

literature.

d + h = 46 cm nosel = d + n(d + 2h)

Where d is the depth of the step, h is the height of the riser,

n the number of steps and l the length of the landing.

l

l

d

h

d

n


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Recommendation for h is 16 to 20 cm, then dshould be 30 to 26 cm.

The width of the staircase should be more than 75

cm. Instead of continuous steps, groups of 5 to 6steps should be preferred. Turning staircases shouldbe avoided. Steps is outdoor staircases should havea slight (1 to 2%) slope towards the nose to run awaythe water.

Stairways should be of fireproof material to givesupport for a longer time. Stairwell acts as achimney. Therefore if should be kept free fromsmoke and gases. This can be achieved by providingtop and bottom ventilation and self-closing firedoors on each landing. Double doors are provided to

form an air lock. In high rise building, positiveventilation pressure is applied in case of fire, to driveaway smokes.

Proper signs and symbols should be marked intraffic aisles. Arrows for escape routes arenecessary.


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Ramps, Runways and Gangways:

The slope of ramps, runways, gangways

etc. should be as small as possible and the

recommended maximum is 150 to the

horizontal. Cleats not more than 40 cm

apart, should be provided on ramps with

steep slopes. Toe-boards should be

provided where a ramp extends over a work

place or a passage. Wire screens are

necessary on the sides, if there is a risk of

materials falling through the sides.

Runways are long with uniform slope as

they are at arodram.


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Floors and Platforms:

The design should consider all types of loadin the form of materials, persons and otherforces acting on the floor. Acid proof brickslaid in acid resistant plaster should be thechoice of flooring for a workroom in whichacids are handled. Unprotected floor edges

situated at heights and openings, sumps,pits etc, in platforms or floors should beprotected by railings, toe-boards or guards.The height of the railing from the baseshould be not less than 90 cm or more than

120 cm. It should have intermediatemembers to shorten the gap less than 47cm. The toe-board should not be less than15 cm in height.


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Floors should be of sufficient strength and

shall never be overload. They should be non-

slippery, free from holes, openings, pinch

points, uneven surfaces, irregularities,

accumulation of oil, water, waste, dust etc.

Near wet processes and water showers,proper drainage should be provided.

Open gutters and floor openings (holes,

chutes, inspection plates) must be fenced or

guarded to protect unwary persons orprevent material falling through it to the floor

below.


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Non-conductive floor in explosiveatmosphere pose special hazard. Discharge

of static electricity generates spark whichcan ignite the explosive mixture near thefloor. Therefore steel tipped or nailed bootsor dropping of steel tools on such floor ishazardous. Such floors must be earthedproperly.

In industry, criteria for floor selection aremany. In addition to strength, comfort andcost, resistance to (a) wear and abrasion (b)chemicals (c) fire (d) environmental factorsand (e) material in process are also to beconsidered.


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Floors are also of many types. Acids andalkali should be avoided on concrete,

granolithic, linoleum, magnestite, quarry tile,ceramic, wood and terrazzo type floor.Solvents and oils should be avoided onrubber, thermoplastic, vinyl and vinylasbestos floor. The cleaning process shouldnot damage the floor affecting its strength oranti-slip properties. Cleaners like soaps,natural detergents, alkaline solution,abrasive powder and damp floor cloths

should be used. Slope is an important factor in floor design. 1

to 2 % gradient towards drain helps ensureto flow away water and keep the surface dry.


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Ladders:

Ladders may be classified under two broad

categories, the portable and the fixed.Since the portable ladder is a ratherhazardous piece of equipment, every effortshould be made, wherever possible, to

replace it by fixed stairs, fixed ladder,scaffolding, or any other suitablearrangement. Not using ladders whererequired is a common cause of seriousaccidents. Men climb on machines,

equipment, boxes, barrels, etc. to getaccess to places above the floor and thusget involved in accidents.


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Ladders should rest on firm ground and its

top should extend at least 1 m above the

place of landing.

Step (Swing back) ladders and folding trestle

ladders: In situations where there is no

suitable facility to lean the ladders, suchladder should be the right choice. Step

(Swing back) ladders are generally provided

with a convenient platform and a hand rail at

the top.


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Fixed ladders: Wherever the length of a fixed

ladder exceeds 9 m, it is necessary toprovide a crinoline for ensuring the safety of

the user. Alternatively, a suitable fall arrester

should be used. In the fall arrester a slide

runs smoothly up and down a steel cablefitted along with the centre of the ladder. The

slide is attached to the users belt by a chain.

The slide moves up and down the cable as

long as the user climbs or descends the slidecauses it to catch on the cable and thus the

fall is arrested (controlled).


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Transport of ladders: Ladders should be

carried always with the leaning end at least 2m above the ground. Long and heavy ladders

should be carried by two or more persons.

The ladder is safest and easiest to climb

when it is at an angle of about 750 to thehorizontal, i.e. a slop of about four vertical to

one horizontal.

Portable ladder should not be more than

20 ft long.


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Non-slip devices for ladder feet: Slipping ofthe feet of the ladder can be prevented by

fixing non-slip ladder shoes to the stiles.They are of fixed or pivoted type, and thesoles may be of rubber, cork, braided rope,leather, felt or lead. Steel spikes or pointed

ferrules fixed to the feet of the stiles, alsoserve as ladder shoes. Lashing the ladder byside guys should be resorted to where noanchorage is available near the top. A verylong ladder should also be tied by guy ropes.


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Climbing ladders: A person ascending ordescending a ladder should always face theladder. Facing away from the ladder while

descending is a dangerous practice. Whenclimbing or descending a ladder, the rungsshould be held firmly hand over hand. It is easierand hence safer for a person to cling on to arung than to a stile, in case the foot slips.

However, in the case of fixed ladders with widesteps and narrow stiles, it is safer to hold thestiles. Tools should be carried in a holsterattached to a belt or in a tool bag or box slungfrom a strap over the shoulder. The safestprocedure is to hoist or lower the tools andmaterials by a rope. There is greater danger ofslipping when the footwear or rungs are wet,dirty or covered with paint, plaster, grease or oil.

Therefore they should be cleaned.


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Work on ladders: Working from the top of asingle ladder can be particularly dangerouswhen the job requires the use of both hands.

The safer way is to stand on a rung about ameter below the top rung to which safety beltis attached. The equilibrium of ladder can beeasily upset if one leans sideways.

Misuse of ladder: Use of trestle ladders assingle ladders can easily lead to accidents.Crawling ladders used over roofs are notdesigned for use as ordinary single ladders.They should be supported throughout their

length. Likewise, single ladders are notdesigned to be used in a horizontal positionas bridges or platforms.


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A door should be closed before

placing ladder over it. Do not use metal

ladder near live electric lines. Use the ladderby facing toward it and not otherwise.

Ladders should not be put on aisle. Do not

rest it on drums, machines, boxes etc. to

reach at height. Filling in cracks and faults orcovering up repaired portions with putty and

paint is a dangerous practice as the potential

weak points are then hidden and cannot be

detected during inspections. Ladders shouldnot be allowed to lie in the open exposed to

the sun and the weather.


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Scaffolding:

General Requirements:

A scaffold is a temporary structure thatprovide support for workers, plant andmaterials used in building, construction,maintenance, repair and demolition work.

The scaffold serves two purposes. One isto provide a convenient platform forpersons to work at height and the other isto provide a safe means of access to allplaces where any person may be required

to work at any time. Accidents at scaffoldsare generally caused either due to directcollapse of the scaffold or as a result ofpersons or material falling off the scaffold.


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The scaffolds should be of sound material,sufficient strength (4 times the expectedload) and properly designed. Their erection,

alteration and dismantling should be doneunder the supervision of a competentperson. They should be securely supportedor suspended and should be properly

strutted or braced to ensure stability. Normalsize is 4 cm thick x 23 cm wide x 3-4 m long.

Steel components of tubular (normally 5 cmdia) scaffolds should conform to IS:2750 and

4014 for Steel Scaffoldings. Wood andbamboo should meet the specifications laiddown by the Forest Research Institute andCollege, Dehra Dun.


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Overhead protection, not more than 3 m

above the work platform of the scaffoldbecomes necessary if overhead work is

going on. Similarly for the persons working

or passing under a scaffold, at least 30 cm

projected canopy or screen should beprovided at the scaffold working level.

In high wind or storm work on scaffold

should the avoided. No hot work should be

carried out on wooden platform. Fire fighting

facility should be kept nearby.


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Means of Access: Failure to provide such

access has caused serious accidents. The

safe means of access may be ladders,portable or fixed, ramps, runways, gangways

or stairways. It is recommended that portable

ladders should not be used as a means of

access where the height of the scaffoldplatforms exceeds 3.75 m. Slope of the

ladder should be 4 vertical to 1 horizontal. It

should rise 1 m above landing platform and

securely fixed at upper end. The use of crossbraces or framework of the scaffold as a

means of access should not be permitted.


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1 If the platform is used as a footing only. 0.7 m

2 If the platform is used for the deposit of

material

0.9 m

3 If the platform is used for support of anyhigher platform

1.1 m

4 If the platform is one upon which stone

or bricks are dressed or roughly shaped

1.3 m

5 If the platform is used for support of any

higher platform and is one upon which

stone or bricks are dressed or roughly

shaped

1.5 m

Width of working platforms: The following minimum

widths are recommended as a general rule.


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Railings and toe-boards: A common cause of

accidents at scaffold is the failure to provide

railings at the exposed sides of the scaffoldplatforms. Often, the failure is when the

scaffolding is erected for jobs of short

duration. Where materials are stacked on a

platform, the height of the toe-board mayhave to be raised; or it may even be

necessary to cover the entire space between

the top rail and the toe-board with wire

netting or planks. Normal height of railing is

1 m and toe board 15 cm.


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Boards and planks in working platforms,gangways and ramps: For platforms of

wooden planks, in general, the spacingshould not exceed the following:

Planks 32 mm thick 1 m

Planks 38 mm thick 1.5 m

Planks 50 mm thick 2.6 m Boards or planks which form part of a

working platform, gangway or ramp shouldnot project beyond their end supports to a

distance exceeding four times the thicknessof the board or plank. 50 mm projection isdesirable. Overlapping of boards is unsafe.


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Hazards and Safety measures: Scaffolds

should never be loaded in excess of the

working load for which they are designed.Wood scaffolds are not generally painted.

However, in case of ladders and certain

permanent types of scaffolds such as the

mobile scaffold, protection is generallyprovided by periodically treating them with a

coating of linseed oil.


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Scaffold foundation should be verified before

erection. Loose or friable packing like bricks

should not be used as support. For heightmore than 15 mt, steel scaffold should be

preferred and not a wooden one.

Inspection after 7 days and after every

damage is necessary. Points to be checkedinclude: stability, ties and fixing, alignment

of members, bending, tightness of lashing or

couplers, planks, platforms, guard rails, toe

boards and condition of ladders.

Warning notice should be displayed near

incomplete or damaged scaffold.


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Dismantling should be carried out in thereversed order to erection. Materials should

not be thrown from heights and should notbe left lying here and there. They should beproperly collected.

After completion of work, all scaffold

materials should be stored in a dry protectedplace using racks, boxes or trays. Thedamaged parts should be replaced orrepaired, cleaned, treated with preservative

or paint. Couplers and other fittings shouldbe lubricated.


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Types of Scaffold:

Some common types of scaffold are as follows:

Pole type scaffolds: It may be an independent structure or the

putlog type erected and supported near wall

or another structure.

The uprights (vertical poles) should rest on

strong foundation to support load without

settlement. They should not be kept more

than 3 mt apart. Tubular uprights have steel

base plates places on wooden sole plates.

Soft ground should be well rammed and

leveled.


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Fixings like steel bolts, nails or fibre rope of

approved size, joint pins and couplers

should be properly fitted. For load bearing

right-angled or swivel couplers should be

used. Putlog members (horizontal) should at

least 10 cm be inserted in wall. Bracing

(diagonal connection) should be tied to

ensure structural stability and prevent

buckling. To prevent overturning the scaffold

should be secured at intervals not greater

than 7.6 m vertically and horizontally.


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Rolling Scaffolds or Mobile Towers:

Such scaffolds move on rollers (wheels) orcastors with wheel locking device. They are

portable and most useful for maintenancework.

To prevent overturning, height should not bemore than three times the minimum width ofthe base. Minimum base length should be 4 ft.

While pushing or pulling the tower, personsshould not ride on it. Tools and materialsshould be removed before moving.

The top working platform must have handrailsand toe boards. It should support 30 lb/ft2

distributed load. Rigidity of the tower issecured by diagonal bracing on all four sidesand on plan.

Moving the tower by pulling at the top orleaning sideways should be avoided.


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Outrigger Scaffolds:

It is a balcony type cantilever scaffold

resting on wall. If other types of scaffoldare possible, this type should not be used.

The outriggers should be passed rightthrough the wall and be secured on the

inner side. Supporting hook between brickjoints is dangerous.

Platform should not project beyond 2 mtfrom the wall. Guard rail and toe board

should be provided.


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Swinging (Hanging) Scaffolds:

Here the platform is hanging by two chain

pulley blokes, ropes and hooks onsupporting beam. Suspended platform can

be raised or lowered as per need.

Movement of both the ends should be

simultaneously. They anchorage and thesuspension gear should be strong enough

to withstand the load with good factor of

safety. Suspension ropes should withstand

6 times the intended load. Rope diametershall be more than 0.75 inch.


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A safety rope shall be provided in addition tothe suspension ropes.

The width of the platform should be morethan 50 cm and less than 90 cm. Guard railsand toe boards necessary on all the threesides open. The platform should be lashed or

secured while in use, to prevent swaying. Each person working on swinging scaffold

should wear safety belt with lifeline attachedto an anchorage other than the scaffold

itself.


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Suspended Scaffolds:

Two or more platform are suspended byropes from overhead outriggers anchoredto the building.

Such scaffolds are designed with a factorof safety 4 and shall never be overloaded.Anchor plates should be tied with U bolts.

Counter weights are used to preventoverturning. Wire ropes (FS 6) are used tosupport scaffold. Hoisting drum (like winch)is used with at least 2 dead turns. Gapbetween handrail and toe board should be

covered by a wire mesh of 38 mm and 16gauge wire. Overhead protection should beprovided if risk of falling objects ispossible.


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Boatswains Chair:

Boatswains chair is used for supporting andhoisting single person in sitting position.

General chair (seat) size is 60 cm x 30 cm,with 25 mm thick timber. Cleats extending infront to at least 23 cm should be securelyfixed under the chair at both ends. The chair issupported by a suitable sling passing through

the four corner holes in the chair for properstability. The suspension rope is fixed to anoverhead support or passed through a pulleyblock fastened to such support. The free endis secured to a conveniently accessibleanchorage and the person in chair must weara safety belt, the life line of which is securedto the tackle supporting the chair. Fibre ropeslings should not be used if the person in thechair has to do welding or cutting work.


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Safety Belts and Harness:

In addition to all engineering controls and

work permits, personal protectiveequipment should not be forgotten while

working at height or depth.

Safety belts of various types are available.

Pole safety belt, general purpose safetybelt with or without remote anchorage and

harness (man hoisting by another man)

type safety belt are in common use. They

should fulfil IS specifications. They are

available in leather and webbing of natural

and man made fibres, of which, webbing is

superior to leather.


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Webbing can withstand loads 3 to 4 timesthat of leather of the same size. Web material

may be cotton, nylon or Dacron. Whileselecting a belt, its normal and emergencyuse should be considered. Life lines ofmanila rope of 19 mm diameter or nylon ropeof 13 mm diameter are suitable provided a

shock absorbing device is available. Care ofbelts is always necessary.

Respiratory equipment should be selecteddepending upon the working environment.

Harness consists of a safety belt and rope orlifeline. It can stop a person falling or he canbe pulled out if working below in a confinedspace.


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General Requirements:

All workers working at height of more than 2

m (window cleaners, construction workersetc.) must wear safety harnesses i.e. safetybelts connected with ropes. The belt shouldbe tied with the body while the free end ofthe rope should be anchored with a fixedunbreakable sound structure or should beheld by another person standing outside aconfined space when the wearer is workinginside. The belt and rope should be of sound

material, examined by a competent personevery six month and maintained in very goodcondition.


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Length of the rope is normally 2 m sincemore fall height and sudden arrest maycause internal injuries to the workers.

But in case of working in depth the ropelength should be more than 2 m andextending upto the bottom level of workingsince the worker is to be pulled out when hegives indication of any difficulty to him orwhen it is observed by the person holdingthe rope, standing outside and watching theperson working inside.

Workers should be trained, encouraged and

supervised to wear safety belt properlybecause it can save their precious lives.

All safety equipment are to be freely suppliedby the employer and it should be seen thatworkers use them. This is a statutory

requirement.


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Safety block (like chain pulley block or hoistingdrum block) is used to connect the wire ropewith the safety belt to allow more freedom of

movement. A sudden pull operates lock or braketo stop the rope. Because of a friction brake onthe rope drum, jolt is avoided and the fallingperson is stopped smoothly. In anotherdesign, a

centrifugal brake is applied on the drum so thatthe person descends slowly to reach the ground.

Tensile tests and drop tests are carried out onsafety belts and apparatus used with them.

Safety belts should be kept in a cool, dry andwell ventilated place. Regular cleaning, visualinspection for defects and repair only b y acompetent person are necessary for goodmaintenance.


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Types of Safety Belts:

Mainly four types of safety belts are in practice:

General purpose Safety Belt:

It consists of a waist belt, a restraining line(lifeline) and the metal components. Strapscovering shoulders, chest, waist and hips arepreferable as by wearing it the forces during

fall will be absorbed not only by the trunk butalso by the legs. Choice of model depends onworking method, time of work, environmentalfactors etc. Rope (normally 2 m) is attached toD ring secured to the waist belt.

For window cleaning, straps are long enoughto fit windows and terminate in snap hooks foranchor on each side of the window. Tworestraining lines are used for window cleaners

belt.


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Linemans or Pole Safety Belt:

To climb on poles, towers, masts, trees etc.

these belts are used. They are used as

support while climbing and protection while

falling. Here waist belt is fitted with 2 D-

rings at different points. The length of therestraining line is adjustable by a buckle.

Generally fall is restricted to 60 cm.


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Harness (Man hoisting) Safety Belt:

It is used for working in a confined space,

silo, tank, vessel etc. The life line is held bya person standing outside to rescue thewearer when he is unable to come out byhis own efforts. On the rescue line there isa wrist strap by which the wearer can behauled up through a manhole or otheropening.

Work permit should be followed and thework place should be made free from any

toxic/flammable vapour and oxygendeficiency.


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Fall Arrester or Anti fall Device:

Here waist belt is connected to a sliding

anti fall device which automatically stopswhile moving in fall direction. Here fallarrest distance is small due to close (short)life line.

Anti fall systems are of two types (1) With asliding and blocking device on a verticalsafety support (pole, cable rail) (2) With anautomatic catching device for rolling,unrolling and blocking a tether (cable, rope,strap). Specific braking system includes anabsorber of kinetic energy used with atether.


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A competent person should be consulted

for selection of appropriate device. A cross

belt is tied with the body and a sliding

mechanism moves with the body in upward

direction but it will be locked and stop the

fall at the descending movement. Other type

allows the horizontal (to and fro) movement

but will catch the falling body through rope

and a shock absorber.


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Safety Nets:

Where safety belt is not possible or inaddition to safety belt for further safety of aperson, particularly when fall height is veryhigh or falling in sea or deep water ispossible, or work surface is fragile andsudden fall is possible, safety net is verymuch essential to catch a falling person.Net is useful to stop a fall of a person aswell as of falling objects. For stoppingfalling material, the mesh size should besmall.

The net and the structure to which it isattached should be capable of catching andsupporting at least two persons at a time.


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The nets are made of synthetic fibres which

are strong, light weight and weatherproof.Diameter of the mesh cords and that of theborder cord should be at least 3 mm and 8mm respectively.

Standard net size is 6 x 4 m but it can bemanufactured of required sizes also. Themesh size of 5 x 5 cm is preferable. Forfalling objects that size should be 3 x 3 cm.

Four corners should have eyes to support.

Big net should have eyes every 2 m on theboarder cords. Two nets can be connectedwith each other to cover more surfaces.


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While attaching net with the structure, somesafety distance should be maintained. It

should not be lower than 3.5 m below theworking level and less than 3.5 m above anyobject or structure below the net. The netmust project at least 2 mt. outside the falling

area. Nets should be cleaned regularly and

checked periodically for cuts and otherobjects. It should have serial number so asto keep record of maintenance.

Nets should be kept on pallets in a dry, cooland well ventilated place. It should be keptaway from chemicals and hot materials.

W ki R f


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Working on Roofs:

Serious accidents happen due to fall ofpersons working on roofs. Fall through

fragile roof sheeting, loss of balance due tothe slope of the roof or effect of wind andinsufficient care while working at the edgeof the roof constitute the principal causesof such accidents which could be

prevented by appropriate safety measureslike crawling or walk-boards, railing, safetybelt and safety net.

Use of a safety belt alone while working ona fragile roof or at a height more than 6 ft(2m) is not permitted. It is dangerous andmany fatal accidents have happenedbecause of this condition. Sound platform,adequate support or safety net should alsobe provided.


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Factors affecting fall of roofers are workingheight, nature, shape and slope of the roof,roof covering material, roof condition and the

weather. Low-strength roofing materials are

asbestosis, cement, glass, plastic, wood androofing tiles. Heat, rain, humidity, pollutionand corrosion spoil the roof condition.Hidden cracks in a roof increase the hazard.

The shape of the roof-flat or sloping with astraight, polygonal or curved profile affectsthe fall direction. Water, oil, snow, moisture,

chemical, dust and other deposits on roofsurface increase fall proneness. High windand bigger sized sheet in hands cause aroofer to lose his balance.


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Whatever may be the reason, danger offalling toward the roof edge or fallingthrough the roof opening is always there.Smoke or gas coming on the roof oroverhead electric power lines alsocontributes hazards.

Roof work should be pre-planned and only fit

and skilled workers should be employed. Assessment of the nature of work and

possible hazards will help to draw safetywork permit. Fixed or mobile scaffold, flatladders (roofers ladder), sufficient cat

ladders or crawling boards side by side,safety belts and nets must be provided toeach roofer.


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Falls through fragile roofing materials: Thecommon practice to walking along the

purling cannot be relied upon. The best wayto prevent falls through such fragilematerials is to use cat or roof ladders. Theyshould be at least 38 cm wide and shouldhave cross battens at least 3.2 cm thick,

fixed not more than 38 cm apart. Safety beltsand fall arrester net should also be used asan additional precaution. A permit-to-worksystem under the control of a responsible

person can help to ensure that the workersare not allowed to work on roofs withouttaking appropriate safety measures.


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Reinforced AC sheets are now available inthe market. They are not a fragile as normal

AC sheets. The manufacturer Eternit EverstLtd., New Delhi, names their product asEverest Lifeguard and tells it a solution forSafety on Roof Tops. Their literature runsas under:

Everest Lifeguard a high strength fibrecement sheet, with Polypropylenereinforcement strips inserted along preciselyengineered locations which run the full

length of the sheet in each corrugation, thusproviding maximum reinforcement strengthwith no loss of durability in service.


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This product has been developed in

conformance of the guidelines issued by

UKs Health & Safety Executive, with regardto Health & Safety on roof work (HSG33).

Falls from sides of roof: In case of flat roofs,

either the standard railings and toe-boards or

a complete barrier to a minimum height of 90cm should be provided. For sloping roofs,

the barrier may be in the form of scaffold

boards extending to a minimum height of 40

cm above the roof surface and a guard rail ata height more than 90 cm but not more than

120 cm.


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Safety Work Permit:

A well designed Permit to Work System is

always useful to check safety points beforehand.

General Precautions while Working at Height:

They are as under_

Cut off power in nearby electric lines to avoid

shock and fall.

Do not lift or carry excessive load so as to

loose balance and fall. Tools should be attached by lanyard to the belt

orgarment to prevent their fall on others.


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Safety helmet, shoes, safety belt, respirator

and other PPEs should be worn as per

need. Keep the work floor always dry, clean and

well protected. The floor should be checked

for fragility, crack and its soundness to

carry load. Non fragile metal sheets orreinforced AC sheets are preferable.

Know safe means of access, emergency

staircase, fire extinguisher, first aid box

and other device like aerial platform, ropeladder etc. before starting the work.


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Pre-employment and periodic medical

examination of workers to check their

suitability for working at height. Workerssuffering from balance disorders, vertigo,

epilepsy, blackouts etc. should not be

employed or continued to work at height.

Trained Workers: Safety belts, harness andlanyards are to be used in conjunction with

permanent anchorage points. Workers

should be trained to know how to check,

wear and adjust before they start work andhow to connect themselves to the structure

or safety time.


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Workers can also use mobile access

equipment i.e. mobile elevating work

platforms, cradles and mast platforms. Allusers of such equipment should be trained

and competent to operate it. They should

also be aware of emergency and evacuation

procedures so that if, for example, the powerto platform fails, they know what they should

do.

It is essential for employers to implementsafe working procedures for working at

heights.


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C fi d S i l d ib d l


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Confined Space is also described as a placewhich_

is mostly enclosed and partially open.

is at atmospheric pressure and temperature. has limited or restricted openings for entry and

exit.

is not designed orintended fornormal place of

work (i.e. not forlong time worker occupancy). has unfavourable natural ventilation due to

stagnant air, no free air movement, oxygendeficiency or enrichment or nitrogenatmosphere.

has contaminated air with toxic or/andflammable gas, dust etc and

may cause engulfment (swallowing) inunstable orloose material.


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Examples (Types) of confined spaces are_

Storage tank

Process Vessels / Reaction vessel

Pressure Vessels

Boilers

Tank cars (trucks) Tank wagons

Digester

Wells/bores Under floor/ Floor opening

Sumps

Pits

Sil


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Silos

Pipes

Ducts Gutters

Tunnels

Sewers

Vats

Bilges

Shafts

Go-down of grain, sulphur, cement, clayand similar loose material

Roof voids/ Gap between roof and falseceiling

Hazards of Confined Space can be classified as_


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Poor lighting and ventilation.

Oxygen deficiency.

Contamination of toxic and / or flammablegases.

Unexpected activation of machinery orflow.

No way or no time available for exit. Engulfment (burying) in loose material.

Non specific work practices.

Other hazards are suffocation, burning,poisoning, explosion, drowning, freezing,crushing, entrapment, scalding, stroke, heatstress, radiation, physical trauma, in jury bymoving machinery, slipping or falling etc.

M f t l d i id t h d


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Many fatal and serious accidents have occurredwhile working in a confined space. Threereasons_ flammable air mixture, toxic gases andoxygen deficiency are found responsible forsuch accidents. Tanks (vessels) with top coveropen but all other sides closed, should beconsidered as a confined space, because, in

such situation persons working inside have toface direct fire, explosion, or toxic exposure andhave no other way to run away except the onlyway of their entry. Therefore doubtlessly and as

per above statutory definition, such situation /condition is a confined space. One worker dieddue to solvent fire, one died due to chloroformvapour and two died due to nitrogen (oxygendeficiency) atmosphere in such confined spaces.


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Safety equipment for working in a confined

space

Following equipment are useful for workingsafely in a confined space.

Vessel Entry Permit:

Tanks vats, pits, sumps, vessels, floor

opening etc. should be protected by guard

rails or cover. Fixed ladder with handrail if

possible, should be provided to step down

safely. Portable (rope) ladder may be usedwhile working inside a tank or vessel for

temporary work.

Other precautions are


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Other precautions are_

Check the concentration of toxic or flammablegas, dust, vapour etc., by a gas detector.

Oxygen content should also be checked forsafe proportion. It should be > 18%.

Air line or self contained breathing apparatusand safety belt are essential.

Sump pumps with flameproof electric orpneumatic motors and air extraction fans(spark proof) and exhaust ducting to removeheavy vapours are necessary.

Complete isolation of the vessel, cleaning,

purging and ventilation of the vessel,inspection and testing, safety permit and allrescue arrangements must be done beforesuch work and only a trained worker will workunder constant help and supervision.

L t t f t d t h ld


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Latest safety and rescue systems shouldbe used. Winch arrangement connectedwith the workers harness in useful to lower

and pull out quickly. Hand freecommunication system is available to keepthe worker in the tank in constant touchwith the supervisor outside. Hand operatedclutch, cord and chair assembly can be

used to lower the person while working atheight or depth.

Bottom drain valve and other nozzlesshould be kept open to allow goodventilation and fresh air in a vessel or tank.

Before allowing vessel (confined space)entry permit, it is necessary to carry outhazard assessment of the space.

WORKING UNDERGROUND


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WORKING UNDERGROUND

Working underground has hazards similar to

working in a confined space. Therefore allprecautions including entry permitmentioned in part 2 above should befollowed.

Under ground work includes digging also.

Hazard assessment of undergroundatmosphere is most important. Oxygen level,measurement and removal of other gases(e.g. H2S, CO, methane etc) by exhaustventilation, artificial lighting (flameproof ifnecessary), necessary ladders, supports,water evacuation, safety harness, helmet,respirators, safety shoes etc. are necessaryas per hazard assessment report.


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