check fittings

cala said:
With a load of 6.3kn ( double ) when you fix a check double how can it double up to 12.6kn, on any system the max load is the weakest link ie. the double at 6.3kn... how can by fitting a check make it 12.6kn...??? each double will slip ( alledgedly ) at 6.3kn....
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the fitting only starts to slip at 6.1kN, but does not actually open or 'fail' - basically, it still retains it's resistance of 6.1kN while slipping (imagine the fitting scraping down along the tube rather than suddenly losing all of it's resistance as soon as the load hits 6.1kN)

{Note: 6.1kN is the design resistance; the characteristic resistance would be 10.0kN, so in reality the fitting would not start to slip at 6.1kN in any case - however, relying on the full 10.0kN without the appropriate factor of safety would not be reccomended, and would not be in accordance with the guidance of BS EN 12811-1}
 
sparkylynch said:
the fitting only starts to slip at 6.1kN, but does not actually open or 'fail' - basically, it still retains it's resistance of 6.1kN while slipping (imagine the fitting scraping down along the tube rather than suddenly losing all of it's resistance as soon as the load hits 6.1kN)

{Note: 6.1kN is the design resistance; the characteristic resistance would be 10.0kN, so in reality the fitting would not start to slip at 6.1kN in any case - however, relying on the full 10.0kN without the appropriate factor of safety would not be reccomended, and would not be in accordance with the guidance of BS EN 12811-1}
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Correct, the two butting fittings work as one thus twice the strength.
 
dico said:
hahaha!!! remember in 2000 aom in pizers sandwhich kent sgb made us put any puncheons or dead legs inside the scaffold just incase any trainees come a long and un done fittings and they dropped lmfao i thought that was what hard hats were for lol!!!
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That must be a sgb thing cos i have always done that. Makes sense to be honest.
 
I suppose there will be slight differences in the way we work but I think that would look pants. Probably not any different and just not used to seeing them on the inside but would you not need to put more in doing that?
 
I would say anything that needs more than one check would have a drawing anyway. No job should be relying on extra check doubles, if done correctly. One check 'just incase'.

It's not just the slip load you have to look at, but the stress on the cup of the double too. Imagine 2 checks under a sticky :nuts:
 
As usual I can't remember the specifics but was there not a formula for working out how many checks on a dropper? This was probably pre en12811 but if you were dropping off a dropper you had to double up the checks with no design input.

Of course it could just have been rigblast were to miserable to get a drawing done.:amuse:
 
dico said:
hahaha!!! remember in 2000 aom in pizers sandwhich kent sgb made us put any puncheons or dead legs inside the scaffold just incase any trainees come a long and un done fittings and they dropped lmfao i thought that was what hard hats were for lol!!!
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DECROMAX said:
That must be a sgb thing cos i have always done that. Makes sense to be honest.
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I've always put them on the outside just like a regular standard, but doubles placed upside down on the handrail, if it's a deadman.

For a puncheon on my course I was told to put both doubles on the handrail upside down though including the upside down one on the ledger below ofcourse. Bit strange considering it was next to the ladder access and supporting both the handrails by the gate. I tried to argue the point but the old fella wasn't going to change his mind.
 
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LD said:
I would say anything that needs more than one check would have a drawing anyway. No job should be relying on extra check doubles, if done correctly. One check 'just incase'.

It's not just the slip load you have to look at, but the stress on the cup of the double too. Imagine 2 checks under a sticky :nuts:
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The test load in the cup (30kN) is far greater than the slip test load the requirement. "Supplementary" couplers are based usually on the slip as the compresive force in the strut tube would then be the next consideration.

"Check couplers" is not the same thing as "supplementary couplers", checks are there just in case, whilst supplementary are there to carry additional load.
 
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I think most scaffs use checks for extra load Allan. Done it myself on racks and top lifts. How are supplementary couplers applied/fixed?
 
frederik said:
I think most scaffs use checks for extra load Allan. Done it myself on racks and top lifts. How are supplementary couplers applied/fixed?
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Morning Frederik
it is the terminology that is incorrect not the application.

The "check" fitting you put at the top and bottom of a hanger is a "Check Fitting" it is there just in case the supporting coupler fails.

The fitting you place behind a support fitting to gain extra capacity is a "supplimentary Coupler" which as you say most scaffs refer to (incorrectley) as a check.
regards
Alan
 
Alan Reade said:
The fitting you place behind a support fitting to gain extra capacity is a "supplimentary Coupler" which as you say most scaffs refer to (incorrectley) as a check.
regards
Alan
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Not sure what you mean here mate.

Like a transom on doubles underneath the ledgers (aberdeen), which helps to support the job for added weight?
 
Similar
When you apply a load into a fitting to induce slip along a tube that is in excess of the allowable slip to resist that slip you need to add a supplimentary coupler behind the fitting which would otherwise slip.

Aberdeens serve the same purpose but are also more along the lines of squaring the scaffold
 
"supplimentary Coupler" ''check" THEYS AREW THE ASAME TYPE OF DOUBBLE ARNT THEY?? YOU DONT NEED AS SPECIAL DOUBBLE FOR THE SUPPLIMENTRY COUPLER AND IF NOT THEN ITS JUST TERMANOLOGY LIKE BEND TO RADIUS
 
scaff1989 said:
"supplimentary Coupler" ''check" THEYS AREW THE ASAME TYPE OF DOUBBLE ARNT THEY?? YOU DONT NEED AS SPECIAL DOUBBLE FOR THE SUPPLIMENTRY COUPLER AND IF NOT THEN ITS JUST TERMANOLOGY LIKE BEND TO RADIUS
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They are the same type of double; however, they "terminology" is what helps you to understand what it is achieving thus a better understanding of what is required.
 
Could you reduce the amount of check (sorry supplementry) fittings if you stuck some chewing gum or loctite between them and the tube?
 
my take on the Aberdeen Transom---when I erect an Independent Scaffold with 90's and Singles I use Abdn T's on every alternative set of Standards, because Singles are not load bearing, if Singles alone were used there would be a danger of the Scaffold ( Splaying ) opening up on the side elevation...

Independent : erected with Band and Plate + Dead Heads do not require Abdn T's because the slip test of the D/H is a ball hair away from the Band and Plate. No Abdn T required.

Independent : erected with Ledger to ledger bracing ( not dog legged )

Independent : erected with 90's and Singles, at each alternative node point use a Band and Plate to secure your Transom to Ledger. No Abdn T required.

I use Abdn T's for mitigation against Splaying on the Lateral Plane not Slippage on the vertical
 
first i ever heard of "Aberdeen transoms" was on here , i aint never had to put transoms under the standards , always just used clips on transoms and swivles and doubles on braces , done some very big work in over 32 years and never seen any any scaffold splay.
with the "Aberdeen transom "
 
some scaffolders on here would think a aberdeen was a steak or a place in britain lol!! but know wheres phills comeing from lets hope when the shareholders of a certain empire reach age and die the olde school scaffolders will come back lol!!!!
 
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