Vent Pipe/Glue

[GallenH]

My 97 PW has always had vent pipes to the roof that are simply PCV tubing; open at the top. I've been thinking about augmenting them with something like this as I've noticed that the pipe is discoloring and probably on its way to brittle:

https://www.amazon.com/dp/B0735N1BTW...v_ov_lig_dp_it

But......I'm always hesitant to screw into the fiberglass roof. I believe that I've read on this forum about adhesives (GM?) that would do the job without screws.

Advice, please.

[GeorgeRa]

I would use 3M VHB double sided type with leveling sealant such as https://www.campingworld.com/dicor-s...SABEgKjXvD_BwE

Another option would be to use polyurethane sealant/adhesive like for example 3M 5200 which would almost become a permanent assembly https://www.amazon.com/3M-5200FC-Mar...35578797&psc=1 or Sikaflex equivalent. Both would be very difficult to remove, a piano wire tool like one use for windshield removal would be an option.

[mikeehlert]

Try 3M VHB tape. Clean roof and cap well with IPA

[Ron J. Moore]

Take a look at Lipperort Industries 398380 on Amazon, fit right in and held without screws. I have seen it installed by other B owners. Ron

[GallenH]

okay, I thought I had read something previously about the tape.

mikeehlert: IPA = alcohol?

GeorgeRa: If I was taping and not screwing, would I need sealant?

[GeorgeRa]

Originally Posted by GallenH

okay, I thought I had read something previously about the tape.

mikeehlert: IPA = alcohol?

GeorgeRa: If I was taping and not screwing, would I need sealant?

Yes, I would use it to seal VHB edge, but it is not necessary, VHB will last years without it. Regarding Isopropyl alcohol I would suggest 99%.

[lmittell]

I'm probably missing something, but why wouldn't this cap work? Installation is simple--push it on the vent tube. A spring clip holds it securely in place.

https://smile.amazon.com/gp/product/...?ie=UTF8&psc=1

EDIT-- I didn't read the OP's message thoroughly and missed the fact that the vent tube has deteriorated, so this cap probably isn't suitable

[GallenH]

The vent tube hasn't broken down. But it's starting to discolor and I'm afraid that getting brittle is probably the upcoming stage.

So on my 97 PW there is no base. It's just a 1-1/4-1-1/2 tube sticking out of the van roof with sealant around the exit.

I was thinking about adding a base around the tube with a cap over it. IOW one of the assemblies that you see by many mfgs on Amazon.

So my OP was.....given that situation....was there some way that I could secure the base of the assembly to the roof without using screws.

Sorry for all the confusion re what my precise situation was.

I think that I'll try to dry fit the base/cap assembly and make sure it clears the existing pipe; put 3M tape on the base, cutting to fit contours; clean with
IPA and stick it on. Then follow GeorgeRa's suggestion of sealant around the base rim to protect the tape.

[magicbus]

In my boating days when mounting antennas, searchlights and such we always drilled, filled the holes and bedded the base with 3M Marine Adhesive Sealant 5200. Excellent stuff.

[mikeehlert]

Originally Posted by GallenH

okay, I thought I had read something previously about the tape.



mikeehlert: IPA = alcohol?



GeorgeRa: If I was taping and not screwing, would I need sealant?

IPA = IsoPropyl Alcohol. I prefer the 92% strength from the Drug store.
Seal everything, even if using tape. Then you don’t forget something.

[Brad1998RD]

Just remember one simple thing. Anything plastic will need to be replaced at some point. So it needs to be able to be removed.

[GallenH]

Thanks everyone. Re Brad's post: Is that 3M tape hard to get off if/when the replacement vent goes?

[mikeehlert]

Not really, rub it and it rolls up. ISO Propol Alcohol removes any residue.

[GeorgeRa]

3 sealants/adhesives are notoriously difficult to remove, silicone, epoxy and polyurethane (3M 5200, Sika etc.). Most of them are crosslinked polymers.

Silicones can be softened with isopropyl alcohol 99% and removed mechanically, piano steel wire tool is best to separate polyurethanes (windshield removal) – there is no solvent, and epoxies need to be removed mechanically. Aqua regia; nitric and hydrochloric acids potent mixture will dissolve epoxy but substrates as well .

[Jill Ellis]

I'm confused why Vent Pipe get damage. its a disturbing fact for me!

looking for a sustainable solution.

[GallenH]

Plastics often don't do very well against the weather. In the Southwest where I'm located, PVC often gets brittle and cracks. The fiberglass top on my RV is fine. My desire to put a cap on has to do with the fact that my RV never had one to begin with. It just has a piece of PVC pipe sticking out the top of the van. That has always bothered me because we frequently park/store under desert trees which have very fine leaves (less than 1/4" sq.) which are held onto the branches by thin stems (like small pine needles) both of which fall continuously (Desert trees that are "evergreen" drop all year round). I'm thinking that a cap would be good protection.

As one responder pointed out, even these caps eventually get damaged by the sun/weather and need replacing. But I figure that it would be a fast fix to buy another unit and just use the cap if the base is still good.

[GeorgeRa]

You can increase life of PVC and prevent yellowing by coating it with a UV resistant paint like for example this one https://www.amazon.com/Rust-Oleum-32...27&s=hi&sr=1-3

On my previous RV I always painted external plastics prone to ugly yellowing. This is another paint good for plastics with color choices. https://www.krylon.com/products/fusion-allinone/