WAZIPOINT Engineering Science & Technology: Schaffolding and Mobile Towers for Construction Industry |Schaffolding Safety

Thursday, August 20, 2020

Schaffolding and Mobile Towers for Construction Industry |Schaffolding Safety

Use safe scaffolding in workplace
Fig- Scaffolding Arrangement

What Should Know About Scaffolding in Construction Project Execution?

All scaffolding must be erected, dismantled and altered in a safe manner.  This is achieved by following the guidance provided by the national and international standard. For scaffolds that fall outside the scope of a generally recognized standard configuration the design must be such that safe erection and dismantling techniques can also be employed throughout the duration of the works. 

To ensure stability for more complex scaffolds, drawings should be produced and, where necessary, these may need to be supplemented with specific instructions.

If SCAFFOLDING  are provided, check:

That only trained people are allowed to erect, alter and
dismantle them?

The uprights are provided with base plates (and where
necessary, timber sole plates)?

The scaffolding is checked daily, after alteration, and
regularly for integrity and soundness?

Is the scaffold secure to the building or structure in enough
places to prevent collapse?

There are double guard rails and toe boards, or other
suitable protection, at every edge, to prevent falling?

Are additional brick guards provided to prevent
materials falling from scaffolds?

Are the working platform fully boarded, and are the boards
arranged to avoid slipping or tripping?

Are there effective barriers or warning notices in place to
stop people using an incomplete scaffold, eg where
working platforms are not fully boarded?

Is the scaffold strong enough to carry the weight the
materials stored on it and are even these distributed?

A competent person check the scaffolding regularly, eg
before use, weekly, and always after it has been altered,
damaged and following extreme weather?

Are the results of the inspections recorded?

Have the wheels of mobile scaffolds been locked when in use
and are the platform empty when they are moved?

The maximum height is 3 times the minimum base

How do use Scaffolding in a Construction Project Site?

It needs to arrange all necessary scaffolding and the like for the crossing of telecommunications or power lines, roads, railways buildings or other obstacles to carry out a construction project. The Contractor shall advise the Employer in each instance of the scaffolding he proposes to use. Drawings of the proposed scaffolding shall be submitted to the appropriate regulatory authorities for approval. 

How do work with Live Line Scaffolds?

The scaffolding which is used to cross specified low, medium and high voltage power lines shall be of such dimensions and allow such clearances that the power lines being crossed may remain in commission during the construction of the new transmission line. Shut-downs on the lines to be crossed may be given for construction of new line but shall not be given continuously for longer periods. Such restrictions in building and use of the scaffolds shall not be grounds for claiming additional costs. Design and construction of the live line scaffold shall not be inferior to the minimum standards outlined in the following clause. 

Live Line Scaffold- Construction 

The scaffold shall be designed to withstand the maximum design wind speed, except that a reduced return period will be accepted. Consideration shall also be given due to impact loading, due to the dropping of the upper phase conductor. 

The scaffold shall, unless otherwise approved by the Employer, consist of 3 m wide 300 mm square mesh nylon nets attached to steel wire ropes running perpendicular to the lower line route, carried by metal scaffolding at 3 m intervals. The nets shall be attached to the catenary wires by means that do not require the presence of any persons on the net or the catenary wires whilst the lower line is alive.

An additional movable walk net laid over the 300 mesh nets may be used whilst the lower line is dead. 

Normally steel or aluminium tubular scaffolding to BS 1139 and BS 6323, should be used, the use of performed units or frames shall be subject to the Employer's approval. 

The mechanical construction shall be in accordance with BS 5950. Reference shall also be made where appropriate to BS 5973. 

The design of the scaffold shall have due regard to the requirements of safety with particular respect to accidental contact with live conductors during construction, use and removal. 

The scaffold including foundations shall be designed and constructed to ensure stability during the process of erection and removal, and also at times when work has ceased for any reason including adverse weather conditions. The foundations shall be suitable for the ground concerned. 

The scaffold shall extend at least 5 m either side of the outermost conductors of the upper line. A maximum of 2 m of this distance may be provided by means of catchers. 

Catchers shall be provided at each end of each scaffold support. The catchers may be vertical or inclined to a maximum angle of 450 from the vertical. They shall be capable of withstanding the specified impact loads without the excessive distortion that would permit a falling conductor to approach or touch a live-line. 

The upper parts of the scaffold shall be provided with softwood rubbing boards or otherwise protected in an approved manner to prevent damage to the conductors resting on or being drawn over the guard. Softwood poles may be used for this purpose. The height of these boards shall be sufficient to prevent the conductor from damaging the nylon net. To avoid damaging the conductors no object other than non-metallic lashing or the catchers shall protrude above the rubbing boards. 

Sufficient endless or double-ended lead lines for hauling over pilot wires shall be placed over the scaffold prior to re-energising of the lower line. 

The side supports shall have working platforms to facilitate the required running of conductors and pilot wires. Working platforms shall be provided with handrails, toe boards and notices warning of the danger of live conductors. The heights of handrails shall be 1m and the toeboards 230 mm. Each working platform shall have a notice plate indicating the 'Safe Climbing Height'. 

The scaffolds shall be fitted with danger plates at intervals of not more than 6m along with the anticlimbing device with at least one plate on each face of the structure.

The scaffolds shall be constructed to prevent unauthorised access or climbing by the use of barbed wire anti-climbing devices, fences or other means approved by the Employer. 

The scaffolding shall be lit with red warning lamps from 1/2 hour before sunset to 1/2 hour after sunrise if erected within 2m from a highway or footpath without an intervening fence. The scaffolding contractor shall provide or arrange for the supply and/or maintenance of these lamps (e.g. with the line contractor). 

If the scaffolding is constructed adjacent to a roadway, a guard constructed from steel drums filled with soil or a soil bund shall be provided and suitably lit. 

Where possible the resistance to earth of the scaffold shall be less than 10 ohms. Special consideration by the Employer and the lower line operator shall be given in cases where this is not attainable with a reasonable number of driven earth rods. 

Bonding the scaffold to the earthing systems of either the live-line or the line under construction is not normally acceptable. In the former case, a nearby line fault could cause the scaffold to become live. In the latter case, a fault between the live-line and the scaffold could cause components of the line under construction to become alive, particularly as it earthing system may not be complete. 

The earth rods should normally be driven into the ground around the outside and approximately 1m from the scaffold structure. The rods should be securely connected electrically and mechanically to the scaffold structure by flexible copper or aluminium leads with minimum cross-sectional areas of 64mm2 or 100mm2 respectively. 

Drawings of the scaffold, complete with details of the clearance plates and earthing arrangement, together with supporting, calculations shall be submitted to the Employer and appropriate regulatory authorities for approval.  

1 comment:

  1. The safety is the key in our work because it's something we have to look to avoid accidents in our business, nice article


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