Self sealing Rivet nuts. Anybody ever used them?

[Mas78]

So I've been thinking about putting a LED light bar on the top of the roof of our combine. I've already got the Astro ADN38 and I've used it a few times with great results and I'm thinking this is the way I want to mount an LED bar, most likely for next years harvest at this point.
I did some searching on here for sealing washers for the rivet nuts and I didn't come up with anything and doing a Google search I came up with some flange sealing rivet nuts on Mcmaster Carr and Fasteners.sherex.com
On Mcmaster they run about $1 each for a 10 pack of 1/4-20 ones, which isn't horrible as one 10 pack should be enough for what I desire to do for now.

McMaster-Carr

McMaster-Carr is the complete source for your plant with over 595,000 products. 98% of products ordered ship from stock and deliver same or next day.

www.mcmaster.com

I was originally just thinking maybe somebody sold a thin washer with rubber/pvc foam ect in the center to seal for this application but haven't found those yet.

Just curious if anybody has ever used any of these flange sealing rivet nuts and if they do weather seal reasonably well or not.
We store the combine in a shed year round, only this time of year does it sit out sometimes at night and get dew and occasional light rain showers so 100% water tight isn't required, just would like to do my best at sealing it up the first time.

 

[GeoBruin]

Never used one and never thought about it before today but it makes sense. I'm sure you probably could source some foam or rubber gaskets with approximately the right ID/OD but if these are readily available, why not make it easy.

 

[Radio Flyer]

I have never used them before either.

Depending on on the mounting, the threads may also be a source of water leaks.

I would look into laying some sealer over the top of the fastener.

Typically, warning light bars on emergency vehicles, that I have seen, us a product like Sikaflex 715 to seal the wire loom through the roof, and a goober over the mounting hardware. Maybe it's just easier for them during assembly?

 

[Mas78]

I thought about the threads as well. Until my searching tonight I didn't know they made blind rivet nuts that encapsulate the bolt.

Thanks for the name of a good speaker for this application. There's still a fair chance I'll use the rivet nuts I already have and silicone them after installing the bolts.

I'm still curious though if these self sealing ones are great or just an added expense that's not really needed.