Holding tank connections

[pitlaw]

My poly holding tank has leaked repeatedly at the fittings. The leak is coming between the nylon fitting and the female poly threads. Should I glue the fitting in with something like 5200 or use more pipe joint tape ( the soft white type)? The threads are not as robust as new ones might be but they are not stripped. Any suggestions appreciated.


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[a64pilot]

I'd go with the teflon tape first, 5200 is sort of permanent when used on something like this, but if you don't mind the permenance, it may be the best chance of success. Teflon tape is easy to undo, and since there should be no pressure, it should work.


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[Conall63]

A few wraps of tape in the correct direction, followed with wiping over the tape with a quality thread sealant, such as "rector seal", also clockwise as for right hand threads. Some quality thread sealants are rector seal, mega lock, gasoila. Thread tape alone is not enough and paste is also needed.

I wouldn't glue the fitting in place. You might want to buy a new fitting or get a die to clean up the threads if threads are questionable. Along looking at fitting threads, running a tap into the tank bung to also clean up those threads. One can rent or borrow taps and dies, or purchase for not much money import sets that are actually decent quality ( think harbor freight) You don't need to tighten extreme, with a turn or two past hand tight with pliers. It's not hard to damage plastic threads. Sometimes when starting a fitting, turn it in counter clockwise until you feel the fitting drop into the male thread, then start turning in the correct direction ( right had threads).

Cheers,

Conall
Conall's Boat Build

[Sailmonkey]

I've installed mine with a Teflon paste pipe dope, hand tight and leak free for 5 years.
A word if caution though, if you over tighten tank fittings, or have over tightened the fittings 5200 may be your only hope, and it will be a permanent "fix".


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[pitlaw]

Pipe dope sounds interesting since tape has not worked in the past, although it
Was maybe just one or two wraps. Part of my problem is the position. The hose
Gets bumped now and then causing flexing and pressure on the fitting. Thanks for the opinions.

[rwidman]

Originally Posted by pitlaw

Pipe dope sounds interesting since tape has not worked in the past, although it
Was maybe just one or two wraps. Part of my problem is the position. The hose
Gets bumped now and then causing flexing and pressure on the fitting. Thanks for the opinions.

One or two wraps is not enough so that may be your problem. Pipe dope (get the kind made for plastic) sounds like a better idea.

[Ziggy]

If the tank is polyethylene, 5200 and most other adhesives will not stick. There are some epoxies that will work, but the surface needs to be flame treated to get strong bond.

[pitlaw]

I think I will try the Teflon paste first. If it works I'll let you know. 5200 doesn't seem like the answer. Thanks.

[pitlaw]

Ok I bought and used "Hercules Real Tuff". PTFE pipe dope. I did not use teflon tape first as some have advised but so far it is not leaking. Thanks.


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[Lepke]

Teflon tape is slick, so it's easier to tighten a fitting with the same effort. Plastic fittings are sometimes damaged because the tape allows tightening beyond the ability of the plastic threads. Standard USA plumbing threads are tapered. The more you tighten, the smaller the hole it's going into. Metal stands over-tightening better.
If I remember right, teflon tape came along as a replacement for pipe dope on metal pipe before plastic plumbing became common.
Some type of paste is the only way I have been able to get a flawless plastic thread seal every time.

[denverd0n]

Originally Posted by pitlaw

I did not use teflon tape first as some have advised but so far it is not leaking.

No need for both. In fact, professional plumbers will tell you to use one or the other, but never both.

[rwidman]

Originally Posted by denverd0n

No need for both. In fact, professional plumbers will tell you to use one or the other, but never both.

I would think even the village idiot would know better than to use Teflon tape and pipe dope on the same connection.

[pitlaw]

I think confusion on that issue comes from the difference between metal threads vs plastics. I have seen CF authorities like Maine Sail suggest both in regards metal to metal. My reading suggests Teflon tape is more of a lubricant that can provide some sealing and pPTFE paste is more sealant in plastic applications. FWIW. Time will tell.

[SVNeko]

Will 5200 even stick to the tank? I doubt it. Anyway, I have used 5200 on bronze fittings and was able to separate them with enough force.

[rwidman]

Originally Posted by pitlaw

I think confusion on that issue comes from the difference between metal threads vs plastics. I have seen CF authorities like Maine Sail suggest both in regards metal to metal. My reading suggests Teflon tape is more of a lubricant that can provide some sealing and pPTFE paste is more sealant in plastic applications. FWIW. Time will tell.

Pipe dope was invented the day after threaded pipe was introduced. Teflon tape is a more recent introduction.

You do not use teflon tape on fuel line connections because of the danger of bits of tape entering the fuel system.

If you want to ensure the electrical continuity of metal to metal connections, pipe dope is preferred.