Water tank access ports still leaking

[JOHNMARDALL]

Originally Posted by SVRocinante

Not sure if it will help, but here are two suggestions:

1. If you can, switch to something like these ports from Vetus; they're great, easy to install and don't leak - period!

https://www.vetus.com/blog/inspection-port-ilt.html

2. If you can't, then my suggestion is to pull it all out and do it again, but using a lot less of the adhesive. More is not better - you want the proper amount of sealant such that you get just a bit of squeeze out when you put them together.

BTW, what are the tanks made of?
It's my understanding that 5200 is not good for Polypropylene and worse for Polyethylene.

Regards,

Thanks for the good word on the ILT ports, Carlos and Maria. A couple of points for the original poster:


1. The ILT ports work by compressing a gasket against the side of the hole in the tank, so it's critically important to buy a holes saw that is exactly the right diameter (look on our website: www.vetus.com). Yes, we sell a hole saw, but you may be able to source one elsewhere. If you go this route, you'll need to use a hole saw of the original size to center the new hole saw - sounds complicated but is not.

2. If you're talking about dripping from the existing ports it might be best to put up with is until you get to somewhere you can work with equipment. I'm a bit concerned that at some point you'll damage the tanks by repeatedly taking the ports out and sanding, and it may be that the internal backing plates are not flat or strong enough to stop the hole edges from distorting as you tighten down, so that nothing will make a watertight seal.


Good luck
John Mardall
Vetus Maxwell Boat Equipment


PS The tanks are probably linear polyethylene.

[a64pilot]

To keep from ruining the trip unless the tanks leak onto something important, I’d let sleeping dogs lie and fix after the trip, once down a few gls they shouldn’t leak much unless in a seaway?

[Emouchet]

I solved my issues with this:
Seabuilt - Access Plate Systems

it is a bit expensive, but boy I like then. A 2 hours project and done!

[Terra Nova]

I've had excellent results from the Henderson access plates. You can reach right through and thru-bolt them.

[Cliffhanger]

Your tanks are almost certainly made of polyethylene (PE) which has a very low surface energy and therefore extremely difficult to glue or bond anything to. Silicone will just peel straight off. The tanks are most likely constructed by heat welding and this is the best way to attach anything to polyethylene. Heat welding really only works when attaching the same material and the inspection hatches are most likely ABS or PVC. As others have said, a mechanical gasket is probably the best option but as PE is quite flexible it will need a lot of fasteners to give an even pressure. There are some bonding adhesives that claim to work well on PE, but I haven't tried them myself. Surface preparation is important. Flame treatment rather than sanding because you are making a chemical bond rather than a mechanical one.

Google "bonding polypropylene"

e.g.

https://www.permabond.com/2015/03/31...-polyethylene/

Hope this is a bit more helpful than some of the other comments.

[SSgtPitt]

Thanks again for the replies.
There is no backing plate inside the tank, so the two rolls of butyl tape I have won’t help this issue. These 3” access ports are all just set into some kind of adhesive. I’d take another picture but I’ve set them and am hoping for the best.
The Henderson access panels look like my winter project, so thanks for that.

We’re at the point now where we’re leaving....period. It’s taken three years to get to this point and leakey water tanks ain’t stopping us. 133 gals minus a little to stop the overflowing should still be ok.

The pressure issue was a good observation. All the vents are operable but the tanks do pressurize a little until they “burp”.

I’ll get some G-Flex and try thatnext.

[captnknopf]

If you search for bonding to poly plastics, one trick that usually helps is to slightly brown the area with a torch before bonding.

[DeepFrz]

One of the problems with sanding an area that has silicone on it is that you just grind the silicone into the plastic, you don't remove it.

[clockwork orange]

I can't tell from the pictures if the ports are bolted but I assume so. I have installed a few ports in tanks and with plastic tanks the tops are usually fairly flexible even though some are quite thick so I make up a backing ring out of 1/4" G10 to bolt to. I will be replacing the ports in my two plastic water tanks this winter, not because they leak but because at 4" I can't get my arm past the elbow so I can't do a proper job of cleaning them out so I want to up them to 5" or 6". The existing ones are plastic welded in with clear lids so a really good install so since I have the tanks out I may see if I can find someone to weld new ones in otherwise I will look in to those Vetus ones.


Steve.

[Compass790]

Yea 5200 wont work on some plastics as you've found out. Better to have the sort of ports you can squeeze up to an o-ring or gasket. Otherwise try something like aquadhere or PVC dinghy adhesive but unless you know what sort of plastic it is it will be a guess as to wether it will work or not.

[thinwater]

Oh dear.

Gaskets are best. If silicone was used in the past, any attempts with adhesives are doomed.

There is an article in Practical Sailor this month on bonding PE. https://www.practical-sailor.com/iss...s_12522-1.html
* 3M5200 is one of the worst bonding agents for PE. It is adhesive for fiberglass, but there are better choices for practically everything else. Sika 291 and Locktite PL S30 are several times stronger on PE.

* The plastic needs to be flamed after sanding to denature the surface. Big difference.

* Silicone is a "no" for this.
* More never solves a sealing problem. Get a fresh start.

[Pete7]

Originally Posted by Terra Nova

I've had excellent results from the Henderson access plates. You can reach right through and thru-bolt them.

I too have used Hendersons lots of times with good results. However, there are a series of shallow protuding rings under the flange which may cause problems with a gasket material. Also there is no inside clamping ring. Vetus used to do an aluminium tank hatch which bolted with gaskets to an inside ring.

Now you are probably wondering how an inside ring wide enough to take bolts from the hatch will fit inside the tank. the answer is there was a cut out which cleverly allowed the inside ring to be slipped into the tank, held in place and then bolted up. I used one of these on a diesel fuel tank on a rib, so subject to quite testing conditions and never had a problem.

If you have time, making a GRP inside ring to bolt to may be the solution if bolts and washers on a Henderson hatch still leaks. BTW Hendersons have altered the number of bolt holes in the hatch. Old ones had something like 20 holes and later models only 10 which makes life a little easier to fit.

Pete

[gmakhs]

Why use 5200 and not a rubber casket or seal ?
Are they leaking from the bottom of from the cap ?
I had a leak on my boat from the depth sounder through hole case , the previous owner was trying to solve it with 5200 and always failing , j just added an o ring .

[Squanderbucks]

What you may need to do is make an inner backing ring to screw/bolt the outer sealing ring with. The inner ring is usually made in two parts to fit inside the opening. If you don’t want to fabricat this there are commercially available kits that are usually sold as fuel tank inspection ports. These come with the gaskets needed.

[clockwork orange]

As I mentioned above, G10 is the best material to make your inside ring as it is very flat and impervious to pretty much any liquid you are likely to have in a tank and you can either through bolt or drill and tap it, I think most inspection ports use either a #8 or maybe #10 fastener. The thing is only a backing plate for clamping purposes so to install it you just cut through it in one spot between fasteners and twist it sideways and wind it in through the hole if that makes sense, no need to cut it in two, that's just silly and makes it harder to install unless its bonded to a gasket which is unnecessary although a gasket can't hurt as long as the holes are a little smaller than the fastener. Cutting G10 does require a carbide blade in a jigsaw, we use a diamond blade on the bandsaw for G10 as we use a lot of it but a boatowner is not likely to have access to this. My sons catamaran has a lot of the Henderson ports in the built in fuel and water tanks and they are indeed excellent.

Steve.