Need a Gasoline-Proof sealant for Polyethylene

[vonsteimel]

I'm a Mechanical Engineer designing light hovercraft. We are using Polyethylene fuel tanks and have a hard time finding anything that sticks to Polyethylene very well.

We have been experiencing leaks around our fuel sending units and need a sealant that can stand up to constant contact of gasoline/oil and fumes (2-stroke). Most "fuel resistant" sealers just turn to mush or fall apart after a few days. And if they do hold up against the fuel/oil they often lose adhesion with the Polyethylene.

Any recommendations?
Thanks,

CS

 

[Compositepro]

You will not get anything to stick reliably. Use metal fittings and neoprene gaskets.

 

[ScottyUK]

The old red Hermetite - if you can find it - and the newer Hylotyte Red are both fuel-resistant and semi-setting. They won't adhere but being semi-setting they may not need to. You'll need a reasonably accurate threaded fitting or flat sealing faces to achieve a good seal.


----------------------------------

If we learn from our mistakes I'm getting a great education!

 

[MikeHalloran]

1. Put all penetrations through the top of the tank.
2. Use a mechanical joint with a seal, e.g. an o-ring.

Spend a day in a junkyard. Look for plastic fuel tanks. Examine how they're mounted and how the connections are made.



Mike Halloran
Pembroke Pines, FL, USA

 

[MintJulep]

Another vote for a gasket or o-ring mechanical seal.

There are very few adhesives or sealants that stick to polyethylene.

If you can tolerate a "permenant" attachment, look at 3M DP-8500, although I'm not sure about its resistance to gas and oil.

If you need a removable-repairable attachment I doubt that you'll find anything suitable.

 

[unclesyd]

I agree with posts above that using a mechanical seal on the top side would be the ultimate goal.
If you have to go the way of using a sealant you might want to give Reltek a call for a specific recommendation

http://www.reltekllc.com/adhesives-for-polypropylene.htm

 

[Ron]

Mike...I like your advice about the junkyard. It's amazing how much you can learn from such escapades. Haven't done it in years...but should.