Rank: Forum user 
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The NASC states that a fitting nut must be torqued to a min of 50Nm, anyone know the maximum before the fitting becomes overstressed? Scaff's are using all sorts of drivers with different torque outputs, one of ours has a Milwaukee M18F1WF12 with torque settings of 130 - 550 and 610Nm so the minimum setting is 130! The majority use Makita DTW285 where the manufacturer recommends the medium setting for scaffolding but doesn't give the torque! Is this situation an accident waiting to happen i.e. the collapse of scaffold structures?
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Rank: Super forum user 
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Doesn't this depend upon the recommmended torque from the fixing manufacturer? If their technical literature states a range e.g. 50 - 100 Nm then your equipment must deliver 50 Nm but no more than 100 Nm If a fixing fails, and it has not been used in accordance with the manufacturers instruction, the only person at fault is the one who miss-used it. If you have full control over your scaffolders why the range of equipment in use? Given these are torque drivers at some stage their calibration requires validation or unit replacement.
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Rank: Super forum user
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Doesn't this depend upon the recommmended torque from the fixing manufacturer? If their technical literature states a range e.g. 50 - 100 Nm then your equipment must deliver 50 Nm but no more than 100 Nm If a fixing fails, and it has not been used in accordance with the manufacturers instruction, the only person at fault is the one who miss-used it. If you have full control over your scaffolders why the range of equipment in use? Given these are torque drivers at some stage their calibration requires validation or unit replacement.
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Rank: Forum user 
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Lloydy,
You are correct in that these bolts can be overtightened and become fatigued to the point they will break.
In my industry I have seen first hand, numerous times, the effects of overtightening on wheel nuts on trucks, resulting in the wheel coming off.
The other thing with scaffold clamps is they are used over and again so could be subjected to overtightening many times over.
There are some useful guides available from various fastener manufacturers on maximum torques and I have provided the link to just one of these so you can see how they work :
https://www.fastenermart.com/files/metric_tighten_torques.pdf
The nut guns these guys are using are not to my knowlege actually calibrated to deliver a specific torque but rather, an approximate value and this will vary depending on the state of charge of the battery etc. (I stand to be corrected if anyone knows differently)
Torque is usually measured either statically with a torque wrench or dynamically using an electronic transducer connected to a meter. Dynamic torque monitorning is to my knowlege only used in manufacturing environments (Once again, I stand to be corrected on this)
The only reliable method I know of for getting the correct torque in that kind of environment is with a calibrated torque wrench.
Do I think scaffolders will use a torque wrench to check the bolts on a scaffold? Not really.
Have you asked the question of the NASC as to how they recommend the job is done?
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Rank: Super forum user
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Hi, to set the scene, I work in a power station environment with a lot of industrial scaffolding going on. So, I have never seen "my" scaffs using power drivers or similar to tighten scaff clips, they always use a scaffolders wrench or ratchet with a "podger" spike on one end.
Thoughts,
- carrying extra weight and awkward trying to get a good angle on a nut
- Additional dropped from height risk unless useing a lanyard (are they?)
- Over torque as aluded to
- logistical issues of charging the devices
- and, one to really think about given the very high number of nuts a scaff will typically tighten or loosen in a day Hand Arm Vibration
So, slightly surprised at use of battery torque devices but then I have seen some really odd scaffold works in shall we say a more public domain than on my tightly controlled multi power station environment. Is this more a "bling" issue than the right tool for the task?
Thanks,
jim
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Rank: Forum user
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A company that i once worked for banned the use of such equipment due to some of the impact guns being used not tightening the fittings up correctly.
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Rank: Forum user
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Thanks for your input Roundtuit, Charlie Brown, ExDeeps and allenwood, it has helped with our research into the use of torque wrenches for scaffolding. The fastener mart bolt tightening sheet from Charlie states a bolt proof load of 83Nm for the zink plated M12 8.8 class, course thread bolt on the CCB drop forge fittings we use. The NASC recommend a minimum 50Nm. So Roundtuit's estimation of 50-100Nm is good to go but we will check it with CCB as recommended and inform the Scaff's.
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Rank: Forum user
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No worries, I was out and about today and guess what I saw? A team of workers erecting a scaffold using impact guns.
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Rank: Forum user
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I am just waiting for our supplier to come back with the manufacturer's torque settings for drop forged fittings, we purchase them from Generation in Cardiff, who buy from CCB Scaffolding Supplies, who in turn get them from China, there's a surprise!
I am now putting together a HAVS register of all the impact wrenches etc. with the manufacturer's vibration ratings and testing them with a torque wrench to confirm, then instructing the Scaff's on which setting to use to prevent under/over tightening the fittings, we can't do any more!
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