[RE-wrenches] Over-torquing Module Clamps?
Jim Duncan
solarguy2004 at gmail.com
Wed Sep 8 11:52:29 EDT 2021
I would have figured that everyone in the PV industry would know about
anti-seize compound by now. SS to SS or SS to Al is prone to seizing
even when not over-tightened. Dis-similar metals everywhere can be
vulnerable to seizing.
Jim Duncan, retired North Texas Renewable Energy Inc 817.917.0527
solarguy2004 at gmail.com
https://www.grainger.com/product/2VFF3
*****************************************
On 9/7/2021 11:36 AM, Jerry Shafer wrote:
> Wrenches
> Per request from Unirac I cut sections off and sent it back to unirac
> and they say that modules that did not come loose we over tightened,
> they do something like magaflux on iron, they could see fractures in
> the rails, aluminum cracks when bent where steel is bending.
> Jerry
>
>
> On Tue, Sep 7, 2021 at 4:30 AM Will White <will at solarenergy.org
> <mailto:will at solarenergy.org>> wrote:
>
> Jerry,
>
> I'm curious, how did they prove over torquing? When doing
> inspections it's easy to find connectors that are under torqued
> but I haven't heard of a reliable way to check for over torque.
>
> Thanks,
> Will
>
> On Mon, Sep 6, 2021 at 1:34 AM Jerry Shafer
> <jerrysgarage01 at gmail.com <mailto:jerrysgarage01 at gmail.com>> wrote:
>
> 1/4" x 20 is no more the 10 ftlbs (120 inlbs) and a good 1/4"
> impact should be able to get you over 30 ftlb. When you
> overtorq bolts and nuts you put undue and irreversible
> stretching and or tearing of the material not to mention
> warping or bending of the plates, and rails, loosening and
> retorqing is a wait as if damage is done its done, the best
> solution is to replace all the stressed hardware. I have seen
> unirac "T" bolts crack the the rails with a bad result, so the
> question is how far do you want to dig and risk to take.
> Regarding cracked glass, I have only seen this with incorrect
> use of the clamps but over torqing will also crush the frames.
> I have inspected arrays after high wind events that resulted
> in destruction of the array and the manufacture in all cases
> used over torq as thier out so warranty are only as good as
> the installers.
> Jerry
> NABCEP PV inspector
>
> On Sun, Sep 5, 2021, 8:56 PM Corey Shalanski
> <coresolar at gmail.com <mailto:coresolar at gmail.com>> wrote:
>
> August,
>
> Thanks for your feedback.The racking model is EcoFoot2+
> <https://ecolibriumsolar.com/ecofoot2plus/> by Ecolibrium
> Solar (now part of Unirac). These module clamps are also
> self-grounding with teeth to bite into the module frame. I
> reached out to the manufacturer, who confirmed that
> the clamp material is aluminum extrusion and the hardware
> is stainless steel.
>
> The modules were installed about 2 weeks ago, so not very
> much time has elapsed to be able to observe potential
> resultant damage. We haven't seen any problems so far.
>
> --
> Corey
>
>
> On Fri, Sep 3, 2021 at 6:35 AM August Goers
> <august at luminalt.com <mailto:august at luminalt.com>> wrote:
>
>
> Hi Corey -
>
> For many years we used Pro Solar racking and Unirac
> Solarmount and tightened the clamps with impact
> drivers. At some point maybe roughly 8 years ago,
> Unirac switched its mid clamps to stainless steel self
> grounding clamps with teeth to bite into the module
> frame. We continued to use impacts with no issue.
> Then, starting around 4 years ago, we started to have
> module glass failures with our SunPower commercial
> systems and these Unirac clamps. We immediately
> switched to torque wrenches for tightening the clamps.
> However, the failures continued. My guess is that the
> poor design of the Unirac mid clamps in conjunction
> with thinner “weaker” module frames exasperated the
> issue. We now have stopped using those mid clamps and
> continue to hand tighten all clamps. We primarily
> install SunPower, and their residential module frames
> have a lip so all the pressure from the clamp doesn’t
> go to the glass.
>
> Getting to your question - what kind of mid clamps
> do you have? If they are aluminum, there may be less
> risk than the stainless clamps. I would be worried
> that the process of loosening and then re-tightening
> might cause more damage than good if there aren’t any
> problems that have occurred to date. It’s a good question.
>
> August
> Luminalt
>
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