Issues with KEE Clamps

[Chris99rogers]

Has anyone had any problems relating to Kee Clamps when getting their suspended lighting rigs or bars re-examined and certified....?

 

Chris

[IRW]

Nope (literally just had two rehearsal room grids inspected).

 

There are certain orientations that Key Clamps are inadvisable for (eg, straight down pull) due to the fact they’re just held with the grub screw- IIRC, usual the done thing is to drill and bolt through if this can’t be avoided.

 

Maybe you could expand on the problems you’ve had identified?

[eamon]

Hi

 

To echo what IRW said, cross bolting is a good thing to do.

 

I have a studio grid at 12m x 12m wide comprised of allen key fittings.

When we started the inspections et al, the company insisted that all joints were drilled & cross bolted.

 

In the process of doing this, we did discover some loose clamps etc. I have not had an issue with different inspection companies since due to the bolting.

 

If you are drilling & bolting, make sure you invest in a very very good drill and really really good drill heads......

 

Eamon

[IRW]

If you are drilling & bolting, make sure you invest in a very very good drill and really really good drill heads.....

 

...and don’t do it through one which the wires for an IWB run...!

[kerry davies]

Are we talking about designing and building a suspension grid using Kee? If so I believe you are using entirely the wrong items. Kee clamps work in compression with grub screws as locators not as fixings. Hanging stuff off them is a no-no. Is that why drilling and bolting is suggested? If so, again, the proper items (scaff clamps, whatever) should replace the Kee.

 

Of course I may have the wrong end of the stick here but Kee are excellent for railings and racking. They are not intended for suspension loading.

 

Chris, just found THISwhich may help?

[Brian]

From the brochure...

 

KEE KLAMP components offer the most flexible solution for the construction of safety barrier systems.

 

...not much mention of anything other than barriers on the website.

 

To get any structure using them certified would need information from the manufacturer regarding their strength. What information that is available only relates to their use in constructing barriers.

[smalljoshua]

Hi Chris,

 

It's not uncommon to see keeclamps used to hold various parts of a stage lighting grid together and this is perfectly fine when there is no actual load on the clamps. E.g. when each disparate element of the grid is correctly suspended. I've been in contact with a few schools and colleges in Devon and Cornwall who have had their rigs condemned by a company who don't understand entertainment rigging. In all cases, we have been able to assess and certificate the rig as safe.

 

We're in Truro quite regularly and can look at this for you. If you email me on josh@nubsound.com I can get you a quote together.

 

Josh

[david.elsbury]

Ok, so I’m looking at a rigging upgrade in one of “our” hotels. It’s fitted with threaded dropper points for 48mm scaff (all fully rated and connected to building steel).

 

I would ideally like to put in short threaded droppers, and use T and + keeclamp fittings to suspend a pipe grid as close to the ceiling as I can get it. (Obv allowing enough space for a hook clamp to pop over the top of the pipe). And it’s got to look slick and clean and tidy as it’s visible on a white ceiling....

 

If I were to use keeclamps then I would have drilled and bolted them... but seeing this thread has reinforced to me why I shouldn’t even be doing that.

 

So what other products out there exist that are acceptable for this? I don’t want the look of scaffolding couplers at all.

 

Thanks!

[Chris99rogers]

I thank you all for you replies and suggestions and a special thanks to Josh at Nub Sounds. I was told that we were the first in the country to have this "issue" but knew that it would have an effect on thousands of installs throughout the country. Just as a follow-up question to the replies, some of you suggested drilling a hole through the Kee clamp casting and the staff bar and putting a bolt through to lock the bar in place to aid the joint when under tension. I had the same idea BUT I was shot down in flames. I was told that the holes would have an effect on the structural integrity of both the clamp and the staff bar and any data supplied by the manufacturers of the clamp or pipe regarding loads would be invalidated... not being either a mechanical engineer or structural engineer I wouldn't be able to contradict... hopefully there's someone out there who can as this would solve a number of my "issues".?

[andy_s]

I would be interested to hear evidence (anecdotal or otherwise) of failure of a lighting grid constructed in the way David Elsbury describes. Does anyone know of any instances?

[ImagineerTom]

If you have an existing grid that is held together with kee clamps and you don't have the budget to replace them with proper fixings then I could see drilling / bolting as an acceptable half way house subject to some proper calculations being done. The fact remains though that the clamps are being used /not/ in the way the manufacturer designed or built them, are being exposed to forces that are far outside those they would experience in their "normal" use, they do not have any tested SWL for lifting/ rigging purposes and as has been noted already the only way to even begin to use them safely is to undertake modifications which do have an impact on the structural integrity of the parts (cast metal has weird issues with defects and flaws in it already - adding the stress of an improperly drilled hole definitely does have an impact) which if we were talking about any other piece of rigging equipment would have members on here up in arms demanding the whole rig be condemned.

 

I understand In the real world lots of rigs are using them extensively but if an accident were to occur I wouldn't see the defence "even though it's against all the designers intentions, there's no independent safety rating and we had to undertake significant modifications but other people do it too" lasting very long?

[david.elsbury]

Ok, Tom, clearly you have a good amount of experience in this area. As per my question above, what’s the better, safer, used-as-designed product to use here? Surely education is the answer here and to encourage people to not use kee clamps for applications where they are suspending grids over peoples heads ?

[ImagineerTom]

I don't design fixed rigs so I lack specific expertise - my default answer would be "there's probably a doughty clamp for this" since all they do is basically "proper" clamps and fixings for theatre. A quick google throws up http://www.doughty-engineering.co.uk/shop/21/index.htm for example.