Inflatable SUP Valve Air Leakage and Repair with Household Silicone Sealant

[elef8eros]

Hello to everyone!
I have a consistent problem with the valve of my inflatable SUP.  It has air leakage around the valve and the cap string (like the one in case "B").

"check photo 2.jpg"

The problem is that after making a special metal tool to tighten and untighten the valve, I tighten it really hard but the problem insists.

Analytically the procedure that I followed is the following:

Untighten the valve, clean all the surfaces, check the rubber seal ring and then tighten it again. After I pumped the SUP, I tighten a bit more the valve to be really tight and to stop the air leakage. Unfortunately, after many tries I didn't managed to fix the air leakage... ☹

I then used teflon thread sealant tape around the black ring on the bottom of the threads and a little bit the first 1-2 threads of the valve. The result did not last long and the air leakage started again.

"check photo 3.jpg"

Some photos from my SUP:

"check photo 4.jpg"
"check photo 5.jpg"

In the following site http://www.boatstogo.com/faq.asp you can find some ideas to fix the problem:
"If you are observing air bubbles around the valve housing perimeter while applying a soapy mixture, there is a possibility that the valve needs to be tightened with a specialized valve tool.

You can also quickly seal the slowly leaking air valve by applying a thin layer of glue around the valve housing perimeter, or putting a drop of glue inside the opening, where the string that secures the valve cover enters the valve housing, if you observe air bubbles at that particular place. Household silicone sealant may also be applied in place of the glue."

So, I'm thinking to fix ones and forever the problem using household silicone sealant around the valve housing and inside the opening of the string.

Has anyone tried this before?

What silicone sealant I must use to have good result and to not destroy my SUP?
For sure I guess I must use a transparent silicone sealant which can be used on PVC material, is water, UV, moisture and temperature resistant.

I'm thinking to use the silicone sealant that you can find on the website http://www.bison.net/static/products/assets/asset_5364_3.pdf with its technical characteristics.

"check photo 6.jpg"

Field of application
Suitable for sealing moving joints, dilatation and connection joints, seams and
cracks in construction, houses, cars, boats and caravans. Ideal for synthetics
(PVC door and window frames, polycarbonate and plexiglas domes), stone and
masonry and (sensitive) metal (copper, zinc, iron, aluminium, brass, stainless
steel). Universal adhesion without primer on all common building materials,
such as concrete, stone, (natural) stone, ceramics, enamel, glass, metal, rubber,
wood and synthetics (acrylic, PVC, ABS, polystyrene, polyester). Does not bond
to bitumen, polyethylene, polypropylene and PTFE.

Properties
· (Sea)water resistant
· UV and all-weather resistant
· Mould resistant
· Neutral, acid-free
· Excellent bonding without primer
· Permanently elastic
· Chemical resistant
· Colourfast
  Resistant to temperatures between -40°C and +100°C
· Easy to apply

What do you think? It is the right silicone sealant to use?

Thank you in advance for your patience and your valuable advices! 😊

[Bean]

Maybe they mean for you to use a silicone lubricant...you can't seriously be thinking about caulking a seal.

I would replace the seal with a fresh one or use a seal conditioner like Autosol, Gummi Pflege.

[elef8eros]

Like silicone paste on this video?



The valve it's like new and I haven't used the SUP so many times, so I don't find any good reason to buy a new valve.

[elef8eros]

Please also check this website:

http://www.nrs.com/boating_tips/valve_know_how.asp

You can read the following:

"When replacing a Military Valve, clean the face of the valve boot and spread a thin layer of silicone sealant around the opening before screwing on the valve. This will help ensure a good seal."

Also check the following in another website:

https://saturninflatableboats.ca/inflatable-boats/how-to-repair/how-to-fix-water-slowly-leaking-into-an-inflatable-boat/

"3.   Drain plug assembly got loose or not enough sealant under the drain valve. Tighten screws on a drain plug while avoiding cracking plastic part. Apply door/window clear silicone sealant around drain valve assembly. Replacement drain plug assemblies are also available on request."



Am I so wrong that I want to use silicone sealant? 

[Bean]

Am I so wrong that I want to use silicone sealant? 

No, its perfect for the purpose that you described. Perhaps I misunderstood where the leak was coming from.

[Green Water Sports]

I would follow the advice in the posted video.

[elef8eros]

I will try to keep you updated about the solutions that I'm working to fix the air leak from the valve.

Please advise and help me if you know a better solution or you have tried any of the solutions that I'm working and you know that it's not gonna work!

First of all I'm uploading some photos of the valve and tomorrow I will upload some solutions that I have tried and failed.

[elef8eros]

As you can see above on photos "Valve 9, 10 & 13" there is a manufacturing defect.

The engineers that designed the mold for the valve to produce it in a injection mold machine, they put the entry of the thermoplastic material directly into the threads!!! Instead they could selected another spot except the threads...! The result is that 4 threads are flattened and they can't do what they are supposed to do... 

I'm thinking that this manufacturing defect of the valve perhaps is the reason of the slow air leaking around the valve.

Below are also some photos of my 1st and 2nd attempt to fix the valve with PTFE (TEFLON) tape.

All the tries were unsuccessful.

[elef8eros]

I tried also to apply silicone sealant around a valve that I don't need and a piece of PVC (piece for repairing inflatable SUP) to test what will happen. I didn't want to apply the silicone directly to my SUP because I didn't know how it will behave.

For one more time my try wan't successful. The silicone come off very easily. So, it has no meaning to try it on the valve of my SUP.

[Green Water Sports]

Valve photo 2, it does not look like you have a good seat for the valve. The white seems to dip back and the red is notched in places. The o ring at the base of the threads and a good seat for the valve to seal against the pvc, negates any thread issue.

I'm trying to visualize this as I don't have a spare valve handy...

[elef8eros]

Yes I have noticed all of these.

I agree especially about the white which dip back and don't provide a good seat for the valve. The red  which is notched in places it's from the inside and I doubt that it has a key role on the air leakage.

The thing is that I used the SUP (which is brand new) for 2-3 months and then the air leakage problem come out.

Let's agree that the thread issue doesn't effect the valve at all and also the red which is notched. How can I provide a better seat for the valve? Which material should I use or what should I do?

[Green Water Sports]

Well the red is presumably the inner PVC layer and sits against the inner part of the valve, the white sits against the outer part. Without a good seat on both sides the seal isn't going to be perfect. The notching may create thicker sections meaning the valve can't tighten down well. I would try to flatten out the red and white PVC as best as possible and center them better when screwing the valve back together.

It is possible that the valve was a bit loose or the board was wrapped to tightly or bent right at the valve section causing the PVC to move and creating the leak after it had been working fine.

[elef8eros]

What you are saying it makes sense.

I will try to flatten out the white and red PVC and center them better before screwing the valve.

Thank you very much for help. 

I want to ask if I put rubber cement like on the video, could this help? If I put rubber cement, will be easy on the future to unscrew again the valve?

[Bean]

To me, it looks like the sealing surface for the main body of that valve is the black O - ring and corresponding seat.  You would likely find a suitable (or slight oversize) replacement at Lowes or H-D.  There could also be grit hidden behind the O - ring that's allowing air to escape. 

As you have already figured out, the body is only threaded in order to provide mechanical pressure on the seal.

[elef8eros]

I just did the job but probably I will have the same problem on the future...

I cut small pieces from the red inner pvc where it was notched to make an even surface for the valve to seat.

Then I screwed really well the valve  and then pumped the SUP. When the pressure was about 10-12 psi, the air leakage began again. I stopped pumping and screw a little bit more the valve. Unfortunately the air leakage in some points increased and in other points decreased.   I guess this is because of the bad construction. The surface where the valve seats is thicker in some points and thinner in other points...

I unscrewed the valve till the air leakage stopped. I left the SUP pumped at 14 psi and I will check it again later to see if it has been eventually fixed. 

I don't think so that there is a grit hidden behind the O-ring because I checked it again and again. Although, the oversized O-ring is a good idea and I will search to buy one because I will need it!

From my point of view, if the valve will be slightly moved or unscrewed, the air leakage will begin again.

Whatever happens I will let you know!