How many companys are working to TG:20 08 ?

daz said:
What about the idea of using aberdeens,and plan bracing to each lift,so that diagonal bracing can be left out so there is nothing fouling access of the working lifts..
Click to expand...


Daz

I've often thought along similar lines for years, although with a maximum lift height of 2100mm on an undesigned scaffold, surely an aberdeen tranny and plan brace would create a 'head banger' on each working lift. It may just be possible to get away with it if you fixed a transom on band & plate at each node point and then fixed your plan bracing to the ledger with swivels. This would be a pain in the arse though considering you would need pretty much the right size tube to avoid clashes - and to keep close enough to your standards for it to be effective - (300mm I think?)

I am also told by our engineers that they are struggling to prove that lift - lift ledger bracing is not required, even when using 'dog bone' tranny's.

Phil.

---------- Post added at 08:59 AM ---------- Previous post was at 08:56 AM ----------

Sorry just read Podger's post dated April 2!
 
Mills 90 and the Aberdeen Transoms

Like you Garry I’m also a great believer in Mills 90 couplings,

I remember the Mills 90s quite well. When tightened to 48 Nm they had a unique gripping action enabling them to carry a load of more than twice the SWL of a drop forged or pressed steel coupling.

When installed correctly the Mills 90 behave more like a shackle by biting into the steel tube as they start taking the load, as opposed to friction clamp type fittings such as the drop forged or pressed steel type, this unique feature of the Mills coupling eliminates any slipping and gives it greater strength. The safe working load of a drop forged or pressed steel double coupling to EN74 Class A is 6.1 kN Whereas a Mills 90 installed under engineering conditions has a safe working load of 12.5 kN.

Even under extreme loading the Mills double will not slip although loads in excess of 4 tonnes have been known to cause shearing of the bolt seating. Another good thing about the Mills 90 is that due to its unique action under load there was never any need to install a check coupling.

However customers would sometimes specify the use of check couplings, and if a check is fitted a clearance of not less than 5 mm between the check and the fitting under load must be left.
The 5 mm gap enables the loaded coupler to rotate slightly as it takes up the load. If that is prevented then the Mills 90 will slip at loads lower than the specified safe working load.

As the Mills 90 needs to rotate to take up its maximum load it can never be used as a supplementary coupler, nor can the load capacity be increased by any other coupler acting as a supplementary to it.

During manufacture the Mills 90 is heat treated to give it a characteristic spring steel property.

When using Mills 90 fittings there is no need to fit an Aberdeen Transom and this is because the main transom can be bearing onto the Ledger but clamped onto the standard with a Mills 90 without clashing with any other coupling.

So why aren’t the Mills 90 still being used? Well one reason is that they are not manufactured to BS EN 12811-1:2003 which tells us that scaffold fittings should comply to BS EN 74-1.
 
Ken

Firstly, thank you for your most interesting Post and I suspect that Technical Data will be well received by both the un-initiated Scaffolder's and Design Engineers.

Why is the Mills 90 not utilised in today's Scaffold Structures ?, with the onset of the demise of the British Manufacturing Base, Quality Assured Component Parts have become more expensive to Manufacture and Import, moreover, the introduction of Asian and Chinese pressed Steel Imports which are in my view are badly finished which gives rise to lacerations and gouging of Tube, ill fitting and become unserviceable after a few cycles of service. I could elaborate but I will leave others to expand on Quality Control.

A Mills 90 installed under Engineering Conditions : Ken, are we talking installed to B.S. 1139---Optimum Serviceability, Reliability, Integrity, Ability and dare I say it deployed to the allocated Torque ?...

Garry...
 
Hi Garry can you ping me a copy over please mate

email pattontwns'aol.com

Cheers Bud

Platinum
 
Alreet Daz

I know what your saying about using aberdeens transoms and plan bracing and doing away with ledger bracing, however the problem that might occur is assuming the lifts are say 2 metre centre to centre, which is your general lift height once your aberdeen is put it place under the ledgers onto the standards this reduces the working lift height by a couple of inches then if you were to proceed and introduce the plan brace, placing the plan brace under the aberdeen which will further reduce the working space again, plus if this plan brace was to dog-leg you know from a plan view, which is best practice in plan bracing, that would mean the next plan brace would go under the last double under the last plan brace onto the standard which would again reduce the lift height space by another couple of inches. According to TG20 you can, as a last resort, put your plan braces in straight from the ledger on the underside of the the above ledger off swivels to gain more height resulting in more space on the working lift, however i dont really like that way, i am sure putting the plan bracing in from the ledgers on swivels will not make the job structure as strong as it would be if were assembled the proper way hence from the standards alternating from outside standard to inside standard through the job, but i am no structural engineer?

Those new transoms crabs or whatever thay are called they are kind of prefabricated transom that fix onto a set of standards that in effect makes it like an aberdeen, when they are used on a tube and fitting scaffold these transoms being in use eliminate the need for ledger to ledger braces.. so they sound like the best bet.

Thank you

Kev
 
Ken Cain said:
Like you Garry I’m also a great believer in Mills 90 couplings,


So why aren’t the Mills 90 still being used? Well one reason is that they are not manufactured to BS EN 12811-1:2003 which tells us that scaffold fittings should comply to BS EN 74-1.
Click to expand...

Good post Cain, and something I wasn't aware of. I'm currently working for Interserve, who bought over Kwikform/GKN/Mills where the fitting originated. We still use the 90s to this day as well as the Mills swivel. A good fitting for certain applications but not for all eg. can't be used on aluminium tube.

Al
 
KenDodd

The first draft of the TG Docs were put in place 08, however, there was great debate and discussion regarding the content---the Technical Data had to be amended several times and an External Engineering Firm had to verify the said Technical Data and Calculations, therefore it took approx two years for the TG Docs to be completed and sanctioned for use---nevertheless, in my humble opinion the TG Docs are not as comprehensive as was intended, these Technical Documents are merely Guidance, therefore, any further Technical Data will have to be identified, verified and implemented by the Individual Organisations Scaffolding Design Department.
 
Tg20:08

Although TG20:08 contains many errors I have been advised by Dave Chapman at NASC that they have no plans to update TG20:08. So it looks like it's going to be around for a tad longer.

I believe there was confusion when it was announced that SG4 was being revised and issued as SG4:10, some people assumed it was TG20 that was being revised.

Ken Cain
 
Garry Adams said:
KenDodd

The first draft of the TG Docs were put in place 08, however, there was great debate and discussion regarding the content---the Technical Data had to be amended several times and an External Engineering Firm had to verify the said Technical Data and Calculations, therefore it took approx two years for the TG Docs to be completed and sanctioned for use---nevertheless, in my humble opinion the TG Docs are not as comprehensive as was intended, these Technical Documents are merely Guidance, therefore, any further Technical Data will have to be identified, verified and implemented by the Individual Organisations Scaffolding Design Department.
Click to expand...

2005 in TG20:05 Garry.
 
Doesn't time fly when your having fun.:D
 
Ken

The TG Documents are an " Enabling " live Document as demonstrated when TG 20:05 was amended and addendum's to TG20:05 created the current TG20:08, perhaps in time the TG Series will evolve and further Guidance will be offered up for consideration.

As and when New Technologies and Systems emerge the SG Series will be amended as demonstrated when Appendix A was bolted on recently.

These Documents are dynamic and in constant flux and although their content is dissemination via the Decision and Policy Makers Media outlets the lack of communication of the subject matter and indeed the lack of consultation with the Scaffolders who actually execute them are somewhat spars thus confusion reigns.

Garry...
 
That's a point Gary, I will now need to remove the phrase "Appendix A" from the paper work and add SG4:10, fekin nightmare trying to keep up.
 
aom

PMSL---what a feckin carry on eh---the amount of paper work created my the Bureaucratic System is not only time consuming it contributing to Global Warming :eek:---all those trees cut down for paper and NASC enlarging their carbon foot print :nuts:.

Aye, A , time flys when yer enjoying yer self :D

WWWwwwooooooooooooooooooooooooooooooooossshh :cry:

Garry...
 
Bore you to tears our job now wouldn't it. There was a time when it made great tv now it's just sitting in an office trying to remember where you have inserted all these buzz words and phrases so you can replace them with this months favourite buzz words and phrases before some wee erse hole with nothing better to do actually reads your risk assessment/method statement and finds your still quoting the factories act circa66.:eek:
 
Yip---theres nothing new under the Sun eh---

Playing all the right notes---but not necessarily in the right order :nuts:
 
i work for a firm that says it as citb scaffs i am the only one even the labours i have told them have to be reg but they take no notice, what can you do or do they just use me and my ticket for all of them,
 
They will just never get to work on any descent site for a national as as you say even the labrador needs a ticket.
 
i was told once that if they adverts and say they registed they are breaking health and saftey laws, and could have the hse, makes you think how they get away with it or would i be held responsorble for it
 
You must log in or register to reply here.
Top Bottom