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Posted By Sean McBreen
I am trying to put together a check list for ensuring that scaffolding contractors, are checking all components to ensure that they are compliaint before they come to site, would anybody have any information in relation to this.
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Posted By Ron Hunter
It may be easier to approach this from the other direction, i.e. ensuring that all defective components are rejected and quarantined/destroyed when the scaffold is dismantled, and/or when the components come back to base.
A common problem with boards is that those which are split, saw marked etc. find there way to the next job.
Similarly,split or rotted boards are cut up for use as sole boards when they are not suitable for that purpose either.
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Posted By Bob Youel
proving torque settings is a big problem
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Posted By Ron Hunter
I confess I've never heard of scaffold fittings being torque set on an independent tied scaffold.
Provision of evidence of pull tests on ties - now that is a problem, but neither of these issues are (IMHO) relevant to the question asked.
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Posted By Garry Adams
Hi sean,
As part of a loss prevention strategy, the regulation of Statutory Torque Values must be of paramount consideration.
A visual inspection of component parts way reveal all patient defects, however to ensure the integrity and reliability of component parts and the subsequent Scaffolding Structure.
Torque values must be addressed.
Bob, has touched on part of the Loss Prevention Strategy, a portion of component parts are are deployed on a Structure well in excess of their allotted torque value , this practice deviates the component part by stretching the fitting in to a plastic range thus putting its reliability and integrity into question.
I posted a question on the discussion forum a few days ago,Scaffolding:Statutory Torque Values, its on page three...however no reply yet.
Regards, Garry...
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Posted By Ron Hunter
Can someone please clarify "Statutory Torque Values"? Surely fittings should be of sufficient size so as to ensure that hand tightening cannot cause deformation?
Did you torque your car wheel nuts last time you changed a wheel?
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Posted By Garry Adams
Statutory Torque Values are allotted to Scaffolding component parts and are enshrined within the Instruments of the British Standards, Metal Scaffolds.
The molecular structure of the amalgams which make up the component are constructed in such a way as to yeild to the elastic range required to deploy the component to the Structure thus producing the frictional stress required to erect a Scaffold.
If the component part is deployed at a torque under its allocated value this will keep the component part within its elastic range and no deviation or metal fatigue will occur. However, it will compromise the Integrity and Reliability of the Structure which may lead to either a partial collapse or a catastrophic failure of a Structure.
If the component part is deployed at a torque value over its allocated value this will subject the component to forces which will put it into its plastic range thus deviation and metal fatigue will develop during its cyclic life time...this in turn will render the component un-serviceable,and contributary factor to collaps.
Regards, Garry...
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Posted By Garry Adams
Clarification,
Quote
British Standard.
Metal Scaffolding:Part 2 ,Couplers.
Section 2.1 Specification for steel couplers, loose spigots and base-plates for use in working scaffolds and falsework made of steel tubes.
5 Materials and design
5.2.1.6
A coupler which is secured by means of a screw shall be so constructed that it will perform satisfactorily when tightened as follows:
Tightening torque shall be indicated by the manufacturer and preferably shall be between 40 and 80 N.m. For types of couplers where hexagon nuts are used with ISO threads, the following torques are preferred:
(a) width across the flats 22 mm: 50 N.m 4.
(B) width across flats 24 mm: 80 N.M.
When tightened with these torques, the maximum stress in screwed component parts shall not be greater than 70% of the yield stress of the material. End Quote.
At this time there is no mechanical mechanism to comply to the aforementioned.
However interest in the research and development of a torque limiting mechanism is gathering pase.
This mechanism will be incorporated within the hexagon head the conventional manually operated spanner.
This provision has many purposes, the main one is to reduce human error.
research and development a torque limiting mechanism o gathering pase.
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Posted By Ron Hunter
So the BS & EN Standards provide just that - standards for the specification, design and manufacture (and where appropriate, type testing) of materials and accessories which make up couplers for tube and fitting type scaffold.
Nothing relates to this being necessarily applied in the field, and it certainly cannot be described as "statutory" torque values.
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