Plastic to Brass/alum fitting sealer?

[Joel Jacobs]

Sears Hardware sells a Devcon product called "Plastic welding system". It's
a two part twin syringe dispenser. It works GREAT on plastics and sticks to
metal pretty good too. Hold your nose when you mix it, stinks really bad.
I think it is an epoxy with some type on plastic solvent mixed in. If you
put a bit on some plastic then wipe it off the surface will be dulled like
it etched it or something. I've even used it to repair broken teeth on
plastic gears. Just not sure if it's fuel proof.
Joel Jacobs

----- Original Message -----
From: "Wayne G. O'Shea" <oifa@irishfield.on.ca>
To: <murphy-rebel@dcsol.com>
Sent: Thursday, May 22, 2003 8:38 AM
Subject: Re: Plastic to Brass/alum fitting sealer?

I read a 2 part epoxy package the other day and it stated "does not stick

to

any plastics"! Guess you proved them wrong aye!!!!

Wayne

----- Original Message -----
From: "Mike Davis" <mike.davis@dcsol.com>
To: <murphy-rebel@dcsol.com>
Sent: Thursday, May 22, 2003 2:06 AM
Subject: Re: Plastic to Brass/alum fitting sealer?

This may seem like a bailing wire fix, but I thought I'd share it

anyway.

I

bought a snow machine 3 years ago with a split/leaking plastic fuel

tank...

I took a wire brush to the crack to rough things up, then worked 30

minute

epoxy into the crack and spread it out on the surrounding "roughed up"

area.

3 years later and many hours of bouncing down the trails at -30F, and

it's

still holding.

Sounds to simple... but if it works, why not!

Mike

----- Original Message -----
From: "Wayne G. O'Shea" <oifa@irishfield.on.ca>
To: <murphy-rebel@dcsol.com>
Sent: Wednesday, May 21, 2003 3:53 PM
Subject: Re: Plastic to Brass/alum fitting sealer?

Thanks Dave!

I'm going to tackle it somehow tomorrow and if they still leak I'm

going

to

rip the tank lids off the wings and build him some real aluminum tanks

out

of my own "pocket"....... as in the long run it will cost me less!!

Thanks again everyone,
Wayne

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[rebel]

Wayne,
For future ref. Polyethylene bonding with epoxy, look at McMaster-Carr p/n
7513A1
Rick D.


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[David Ricker]

Wayne

I was thinking more about this problem and remembered using some Parker O-ring
sealed fittings. If there is enough wall thickness to fit them in, the Parker
ZHBA (Alumunum) series might be an option. It is a straight thread fitting
sealed by an O-ring so you would tap the hole and do a counterbore around the
hole for the O-ring to fit into. You might be able to undercut the fitting to
recess the O-ring rather than C'bore the tank. We used this type of fitting on
the oil filled assemblies I mentioned earlier.

They have some face seal products too but with my dial-up connection the
catalogs are too big to download & go through.

Aeroquip has a series (in British std parallel thread or metric!) which uses a
metal ring to capture the O-ring OD so this might be an option for someone like
you who has a lathe and can make up some small parts. The Aeroquip # is GG308
or GG108, JIC 37 deg to metric.

I am thinking more & more that a mechanical seal (O-ring) might be better in the
long run than trying to glue something to the PE of these tanks. In fact, this
might be a better choice than the black goop for the fuel outlet and sight gauge
fittings for the Rebel/SR tanks, what do you think?

Hope this isn't too late to be useful!

Cheers,

Dave


"Wayne G. O'Shea" wrote:

Thanks Dave!

I'm going to tackle it somehow tomorrow and if they still leak I'm going to
rip the tank lids off the wings and build him some real aluminum tanks out
of my own "pocket"....... as in the long run it will cost me less!!

Thanks again everyone,
Wayne

----- Original Message -----
From: "David Ricker" <ricker@dbis.ns.ca>
To: <murphy-rebel@dcsol.com>
Sent: Wednesday, May 21, 2003 7:48 PM
Subject: Re: Plastic to Brass/alum fitting sealer?

Wayne

I don't know about being knowledgable but I might as well toss out a few

ideas

in case it makes someone think of a solution.

On the adhesives I'm not sure if there is anything that will stick to PE

very

well but here are a couple of ideas. Given any though to hot melt

adhesives? I

don't know of any particular one but there might be a formulation that

would

take to the PE tanks. Give your local industrial adhesive rep. a call &

see if

you can get a sample & a gun to apply it. I was looking at using one of

the

"Engineering" grades on a project a while back and the rep for Amisol (?)

was

helpful.

Another idea would be one of the castable polyurethanes like Devcon

Flexane 80.

Cast it around the leaky fitting in a bump covering it and spreading out

around

the fitting. We used to make isolation mounts for electronic enclosures

which

were immersed in mineral & silicone oils and that worked well in that
application. After cure it is about 80 durometer so it can flex with the

tank

if need be. We cast right to the aluminum but I can't say how it would

adhere

to the PE, maybe the Devcon rep can answer that.

You might want to try and put a bulkhead fitting in the tank and use that

as a

via for the fuel line (see US Plastics, usplastic.com, P/N 16421 or

similar)

they use a gasket which is compressed against the side of the tank.

Outside of that, the plastic welding sounds like as good an ideas as any

(except

maybe an aircraft bladder....), perhaps you could weld some robust flanges

on

where the tubes have to pass through and thread fittings into the flange.

US Plastics sell the plastic welding guns (like P/N 41066) and a how to

booklet

(I have it, seems to make sense). They say you need nitrogen to weld PE

though.

Well hope this is useful, be nice to be able to help you for a change!

Cheers,

Dave R.

"Wayne G. O'Shea" wrote:

My turn to ask a question from all you well rounded knowledgeable

people!

Having a problem with a customers Pegastol (read shitbox from K'beck!!)

that

has terrible rotomoulded plastic wing & main tanks. It's been an ongoing
battle to try and seal his outlets and drains to keep them from dripping

or

weeping. Have tried numerous sealers over the last year + and even the

fuel

proof stuff seems to let go with his Esso premium car gas. Seal All,

Goop,

Permatex hardening etc all let the fuel get by.

Tomorrows attempt is going to be proseal, but thought I would throw my

hands

up in case someone has a better solution as I'm not sure if Proseal is

going

to bit into the plastic either.

Tanks are a slippery white polyethylene (I beleive) and some fittings

are

plastic, some brass, some alum.

THANKS!
Wayne O'Shea
www.irishfield.on.ca
oifa@irishfield.on.ca

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--
David A. Ricker P. Eng.
DARTEC Engineering Inc.
3 Tamarac Drive
Fall River, Nova Scotia
Canada, B2T 1E8
ricker@dbis.ns.ca
Ph. 902-860-0256




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[Wayne G. O'Shea]

Dave, nothing is ever too late to be useful, as even if this attempt doesn't
work there is always the next one!!

THANKS ! Dave, Grant, Terry, Dave, Mike, Joel and EVERYONE else that has
offered advise on these PE wing tanks that I have been battling in a
customers Pegastol.

Late last night I (ignored you all and ! ) tackled it with Proseal by
first cleaned everything with spray cleaner for circuit boards. Then I used
a Popsicle stick and lined the inside edge of the threaded hole with proseal
by scrapping it off the stick, coated the female threads and smeared a good
lip around the outside of the hole as well. Then I coated the end of the
fitting with a build up and coated the threads then inserted. Then filleted
the fitting to tank area into the smeared layer of Proseal (using a small
flattened wire as I only had the 3/32 area to work between fitting and wing
skin). When it hardens it >SHOULD< be like a grommet inside to out on the
tank.

There were many good suggestions on various sealers and operations. Grant
has had good luck with Yellow heavy "natural gas/propane" Teflon tape
wrapped about three layers deep etc. The threads on the outlet fittings
inside the wing were pretty much stripped so this was out and other
suggestions like counter boring a spot for O-rings etc were a no go as I was
working through a 4" inspection hole and reaching a foot over for the outlet
hole and the wing drains are through a hole about 3/32 bigger than the
fitting being thread in and if I tried to cut that out with anything I was
bound to be in the bottom of the PE tank. I had also tried machining a
fitting for an O-ring on the last round and even with some Seal-All on it
for reassurance fuel wept by the whole mess as you can't tighten the
fittings enough in to this soft garbage material for a tank!

Hopefully after next weekend I will have good news, when the customer fills
them to head off to the lake. I may even suggest that he takes the fuel can
with him (and land on a lake half way to top his nose tank) and not use the
wing tanks for about 3 weeks to give the Proseal lots of time to harden up
before he hits it with his Esso Premium........ that I'm sure has some
terrible additive in it that has been eating all the previous sealing
attempts with stuff labeled gas proof including fuel tank repair materials!

It's unfortunate with car gas that the game keeps changing. Sunoco used to
have the best premium and then they went and admittedly added alcohol to it.
My trucks engine light comes on if I use Shell products, but nobody else's
gas bars do this to it, so were do you start looking for a good source of
auto-premium for a Rotax?!

Cheers,
Wayne

----- Original Message -----
From: "David Ricker" <ricker@dbis.ns.ca>
To: <murphy-rebel@dcsol.com>
Sent: Friday, May 23, 2003 10:45 AM
Subject: Re: Plastic to Brass/alum fitting sealer?

Wayne

I was thinking more about this problem and remembered using some Parker

O-ring

sealed fittings. If there is enough wall thickness to fit them in, the

Parker

ZHBA (Alumunum) series might be an option. It is a straight thread

fitting

sealed by an O-ring so you would tap the hole and do a counterbore around

the

hole for the O-ring to fit into. You might be able to undercut the

fitting to

recess the O-ring rather than C'bore the tank. We used this type of

fitting on

the oil filled assemblies I mentioned earlier.

They have some face seal products too but with my dial-up connection the
catalogs are too big to download & go through.

Aeroquip has a series (in British std parallel thread or metric!) which

uses a

metal ring to capture the O-ring OD so this might be an option for someone

like

you who has a lathe and can make up some small parts. The Aeroquip # is

GG308

or GG108, JIC 37 deg to metric.

I am thinking more & more that a mechanical seal (O-ring) might be better

in the

long run than trying to glue something to the PE of these tanks. In fact,

this

might be a better choice than the black goop for the fuel outlet and sight

gauge

fittings for the Rebel/SR tanks, what do you think?

Hope this isn't too late to be useful!

Cheers,

Dave

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