Is there a purpose to 3 (yes 3) check/supplementary fittings?

one kier design kas 3 no ladder beams and seems to be easier than their tube only ones that a really hard to fix due to closeness of tubes ....

also no puncheons all tubes have to be cut to size
 
av scaffolded my head in a few of these loading bay when to duck out between the transome and hard hat wouldtn fit threw ahahah






timthumb said:
one kier design kas 3 no ladder beams and seems to be easier than their tube only ones that a really hard to fix due to closeness of tubes ....

also no puncheons all tubes have to be cut to size
Click to expand...


thern topped out and cut again we punch up of outs only tube we cut to size is the fist lift but now and again you see a jack in them
 
Morning All,
Check coupler /Supplementary Couplers, a regular topic but here we go again.
For years we have banked these fittings to their specified values and taken the full value. I remember doing raking shores with 6 supplementary couplers but as with all things times have indeed moved on.

AsXD has an idea that a single supplementary is allowed and he is correct that is the norm. (TG14:03)
He is also correct in his assertion that there may be better ways to get the same result without banking.

With regards the question as to their requirement I would err on the side of caution as at a guess someone has considered the case before it got to you and may have more information than you about the load to be applied.

The load you are writing on your sign is 1900kg (just a little shy of 2tonne). You make no mention of the size or shape of the load nor do you mention how it is to arrive on the platform.

Let’s assume it is on a 1.0m x 1.0m pallet and it will be placed on the platform y a forklift or crane.
The mechanical means of load delivery calls for a 25% increase for impact now your 1900 looks like2375kg. Now remember your load is 1.0m x 1.0m that’s around 23kN/m2 (close to 500lb/ft. Sq.) close to 5 times the design requirement of Phil’s gantry. (not sure about the hoist load on that gantry Phil)

Whilst I am not advocating the content of your design or your loading tower I am drawing your attention to the unknown element of your question, the above may be a reason for the design you have. (there may still be better ways to resolve it)

For future reference with regards the “Coupler Capacity”

Below is an extract from TG14:03 you will not that this indicates FULL VALUE on the Supplementary Coupler.

Supplementary couplers are added where the estimated working force in a scaffold tube at its
connection point is greater than the maximum safe working load capacity of a single load-bearing
coupler.
Supplementary couplers are sometimes incorrectly referred to as check couplers, safety couplers,
or back-up couplers. Supplementary couplers are active couplers which add known strength to
the connection whereas check couplers are used to give added security in situations of high risk
to personnel.
Typical design applications where high coupler forces could be expected and which may require
the use of supplementary couplers are:-
Diagonal braces in the lower lifts of a scaffold
Suspended and slung scaffolds
Cantilever loading platforms
Lifting gantries
Truss-out and cantilever scaffolds
Loading towers
Falsework structures
Pedestrian bridges and walkways
Because of the ultimate strength limitations on the main coupler, a supplementary coupler
arrangement is normally limited to the use of one main coupler plus one supplementary coupler,which could be expected to give the following maximum safe working loads:-
Supplementary coupler Maximum safe
working load
Two Class A right angle couplers = 12.50kN
Two Class B right angle couplers = 18.75kN
Two Swivel Couplers = 10.60kN
(NOTE: As recommended in clause 39.8.2 of BS 5973:1993 the advice of the coupler
manufacturer should always be sought.)
I of 2 June 2003
If the estimated force in the tube is in excess of these maximum safe working load figures, then
either further advice should be sought from the coupler manufacturer/supplier as to the load
bearing capacity of their particular couplers or an alternative scaffold design solution should be
sought.
Only right-angle couplers (also known as doubles) or swivel couplers should be used as
supplementary couplers. Putlog couplers (also known as singles or half couplers) should never be
used in this application.
Because BS 1139 does not contain any test requirements for supplementary couplers, it is
recommended that the coupler manufacturer's advice should be sought as to the suitability of his
couplers to act as supplementary couplers, the manner in which they must be used and the safe
working loads.
I Check Couplers
Typical design applications where high risk to personnel situations may arise and which may
require the use of check couplers are:-
Hanger tubes
Suspended or slung scaffolds
Truss-out scaffolds
Only right-angle couplers (also known as doubles) or swivel couplers should be used as check
couplers. Putlog couplers (also known as singles or half couplers) should never be used in this
application.Where a combination of high coupler forces and a high risk to personnel simultaneously occurs, it
may be necessary to install a supplementary coupler arrangement plus a check coupler or an
alternative scaffold design solution should be considered.
 
Last edited:
Alan Reade said:
Morning All,
Check coupler /Supplementary Couplers, a regular topic but here we go again.
For years we have banked these fittings to their specified values and taken the full value. I remember doing raking shores with 6 supplementary couplers but as with all things times have indeed moved on.

AsXD has an idea that a single supplementary is allowed and he is correct that is the norm. (TG14:03)
He is also correct in his assertion that there may be better ways to get the same result without banking.

With regards the question as to their requirement I would err on the side of caution as at a guess someone has considered the case before it got to you and may have more information than you about the load to be applied.

The load you are writing on your sign is 1900kg (just a little shy of 2tonne). You make no mention of the size or shape of the load nor do you mention how it is to arrive on the platform.

Let’s assume it is on a 1.0m x 1.0m pallet and it will be placed on the platform y a forklift or crane.
The mechanical means of load delivery calls for a 25% increase for impact now your 1900 looks like2375kg. Now remember your load is 1.0m x 1.0m that’s around 23kN/m2 (close to 500lb/ft. Sq.) close to 5 times the design requirement of Phil’s gantry. (not sure about the hoist load on that gantry Phil)

Whilst I am not advocating the content of your design or your loading tower I am drawing your attention to the unknown element of your question, the above may be a reason for the design you have. (there may still be better ways to resolve it)

For future reference with regards the “Coupler Capacity”

Below is an extract from TG14:03 you will not that this indicates FULL VALUE on the Supplementary Coupler.

Supplementary couplers are added where the estimated working force in a scaffold tube at its
connection point is greater than the maximum safe working load capacity of a single load-bearing
coupler.
Supplementary couplers are sometimes incorrectly referred to as check couplers, safety couplers,
or back-up couplers. Supplementary couplers are active couplers which add known strength to
the connection whereas check couplers are used to give added security in situations of high risk
to personnel.
Typical design applications where high coupler forces could be expected and which may require
the use of supplementary couplers are:-
Diagonal braces in the lower lifts of a scaffold
Suspended and slung scaffolds
Cantilever loading platforms
Lifting gantries
Truss-out and cantilever scaffolds
Loading towers
Falsework structures
Pedestrian bridges and walkways
Because of the ultimate strength limitations on the main coupler, a supplementary coupler
arrangement is normally limited to the use of one main coupler plus one supplementary coupler,which could be expected to give the following maximum safe working loads:-
Supplementary coupler Maximum safe
working load
Two Class A right angle couplers = 12.50kN
Two Class B right angle couplers = 18.75kN
Two Swivel Couplers = 10.60kN
(NOTE: As recommended in clause 39.8.2 of BS 5973:1993 the advice of the coupler
manufacturer should always be sought.)
I of 2 June 2003
If the estimated force in the tube is in excess of these maximum safe working load figures, then
either further advice should be sought from the coupler manufacturer/supplier as to the load
bearing capacity of their particular couplers or an alternative scaffold design solution should be
sought.
Only right-angle couplers (also known as doubles) or swivel couplers should be used as
supplementary couplers. Putlog couplers (also known as singles or half couplers) should never be
used in this application.
Because BS 1139 does not contain any test requirements for supplementary couplers, it is
recommended that the coupler manufacturer's advice should be sought as to the suitability of his
couplers to act as supplementary couplers, the manner in which they must be used and the safe
working loads.
I Check Couplers
Typical design applications where high risk to personnel situations may arise and which may
require the use of check couplers are:-
Hanger tubes
Suspended or slung scaffolds
Truss-out scaffolds
Only right-angle couplers (also known as doubles) or swivel couplers should be used as check
couplers. Putlog couplers (also known as singles or half couplers) should never be used in this
application.Where a combination of high coupler forces and a high risk to personnel simultaneously occurs, it
may be necessary to install a supplementary coupler arrangement plus a check coupler or an
alternative scaffold design solution should be considered.
Click to expand...
F uck me...
 
Supplementary coupler Maximum safe
working load
Two Class A right angle couplers = 12.50kN
Two Class B right angle couplers = 18.75kN
Two Swivel Couplers = 10.60kN

As a double and a swivel (Used as Checks) have one gate and one bolt fixed to the standard (or brace,before someone bites my head off) why is there such a difference in the loading ?
 
scaffman1 said:
Supplementary coupler Maximum safe
working load
Two Class A right angle couplers = 12.50kN
Two Class B right angle couplers = 18.75kN
Two Swivel Couplers = 10.60kN

As a double and a swivel (Used as Checks) have one gate and one bolt fixed to the standard (or brace,before someone bites my head off) why is there such a difference in the loading ?
Click to expand...

The double is a solid coupler the swivel is jointed in the middle with a pin, considered to the weak point.

The swivel was downrated some years ago, used to be the same as a double, again times move on etc..
 
Last edited:
Alan Reade said:
The double is a solid coupler the swivel is jointed in the middle with a pin, considered to the weak point.

The swivel was douwnrated some years ago, used to be the same as a double, again times move on etc..
Click to expand...

Cheers Al, But it does not explain, when used as a check where the pin is not used at all, why there is such a difference.
 
The problem is that SWLs are now calculated as kenetic weights giving the designers a problem working out the true weight whilst in motion . So they just add on as much as they can to cover their backsides . You have to wonder if they take the tube tollarence into account if they are asking for three checks .
 
Alan Reade said:
The double is a solid coupler the swivel is jointed in the middle with a pin, considered to the weak point.

The swivel was douwnrated some years ago, used to be the same as a double, again times move on etc..
Click to expand...

I hope you are reading this Frederik, reminds me of a thread a while back.:laugh:
 
scaffarobbo said:
The problem is that SWLs are now calculated as kenetic weights giving the designers a problem working out the true weight whilst in motion . So they just add on as much as they can to cover their backsides . You have to wonder if they take the tube tollarence into account if they are asking for three checks .
Click to expand...

Assuming the 3 "supplementary" couplers plus the main coupler are all considered at full capacity they woudl total 24.5kN a 2m lift is around 29kN. Most progressive loading towers would be on 1.5m or less giving a capacity of closer to 36kN.
Hope this is of help to you scaffarobbo
 
Redrow,Bell way etc are all giving us designs for loading bays showing no increase in standards just more transoms ,soon you won't need boards just shitloads of clips and tens!
 
aom said:
I hope you are reading this Frederik, reminds me of a thread a while back.:laugh:
Click to expand...

Gis a clue Alistair,twisting me tash off here:D

As usual exellent info form Alan,alround informative comments from forum designers.
Flinty,your questions answered,now gooooo get em!
 
I thought that Jigman. Is the difference between class a and b
 
frederik said:
Gis a clue Alistair,twisting me tash off here:D

As usual exellent info form Alan,alround informative comments from forum designers.
Flinty,your questions answered,now gooooo get em!
Click to expand...


Come on, I was scarred for life you didn't believe me that a swivel might be in certain situations but probably not in this case a load bearing fitting.;) It was a while back and can't be bothered looking back to be honest.:embarrest:
 
Alan Reade said:
The load you are writing on your sign is 1900kg (just a little shy of 2tonne). You make no mention of the size or shape of the load nor do you mention how it is to arrive on the platform.

Let’s assume it is on a 1.0m x 1.0m pallet and it will be placed on the platform y a forklift or crane.
The mechanical means of load delivery calls for a 25% increase for impact now your 1900 looks like2375kg. Now remember your load is 1.0m x 1.0m that’s around 23kN/m2 (close to 500lb/ft. Sq.) close to 5 times the design requirement of Phil’s gantry. (not sure about the hoist load on that gantry Phil)

Whilst I am not advocating the content of your design or your loading tower I am drawing your attention to the unknown element of your question, the above may be a reason for the design you have. (there may still be better ways to resolve it)
Click to expand...

The load is delivered by forklift, I don't know the exact measurements but they are standard for building sites, a pallet with bricks/blocks and a bucket of muck. I think the drawing itself even shows diagrams of what it can take (though I still haven't got it to hand sorry)

Supplementary couplers are added where the estimated working force in a scaffold tube at its
connection point is greater than the maximum safe working load capacity of a single load-bearing
coupler.
Supplementary couplers are sometimes incorrectly referred to as check couplers, safety couplers,
or back-up couplers. Supplementary couplers are active couplers which add known strength to
the connection whereas check couplers are used to give added security in situations of high risk
to personnel.......
Because of the ultimate strength limitations on the main coupler, a supplementary coupler arrangement is normally limited to the use of one main coupler plus one supplementary coupler..........................
Where a combination of high coupler forces and a high risk to personnel simultaneously occurs, it
may be necessary to install a supplementary coupler arrangement plus a check coupler or an
alternative scaffold design solution should be considered.
Click to expand...

Is this saying in normal circumstances there should only be one supplementary fitting, and one check (though you could have both together?)

Thanks as always for your replies.
 
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