Fitting in fiberglass diesel fuel tanks

[motion30]

I'm making plans to build fiberglass fuel tank to replace my leaking steel tank . one question I have..... what is the best way to put fittings in a fiberglass tank?

[tronic72]

I'd suggest using stainless or brass fittings and glueing them on top of your holes in the glass. There are fuel resistant glues or an epoxy but you'd have to check with manufacturers. I'd do some trials on sons other glass before you install on the final tank. I'd make a small box and attach fittings to ensure that ever product you use doesn't leak. It wouldn't need to be thick or pretty.

[DeepFrz]

West Systems has a must read article (IMO) on building fiberglass/epoxy tanks. It's on their web site.

[thinwater]

You can buy fiberglass couplings and cast them in. The bond is more sure. I have also bonded brass fittings. ALWAYS internal threads, because you won't bung them up during installation. NEVER use nipples.

Install a inspection port for cleaning right now, 4" minimum.

[motion30]

Originally Posted by thinwater

You can buy fiberglass couplings and cast them in. The bond is more sure. I have also bonded brass fittings. ALWAYS internal threads, because you won't bung them up during installation. NEVER use nipples.

Install a inspection port for cleaning right now, 4" minimum.

I was thinking about using brass bulkhead fittings. How did you bed them in with epoxy or flexible sealer?

[GILow]

I started a thread on my day tank build here a while back, there were some excellent suggestions posted to that thread. In summary, I ended up bedding in the brass fittings I needed using epoxy. But according to advice I received on the thread, doing it this way can weep diesel. There were suggestions on how to avoid this posted to the thread, I cannot remember what was recommended. I am fortunate as my tank build allowed me to put all the fittings at the top of the tank which remains mainly dry so there has not been even a hint of weeping fuel around any of the fittings yet.

[GRIT]

We built our tanks in epoxy/glass, with 1/2" core. We pressure tested them as per ABYC and Canadian regulations, at 4psi overnight, and had no loss in pressure. All but one fitting are located at the top of the tanks. We also have one on the bottom of the tank.

All fittings are potted in thickened epoxy, with a generous buffer between the fitting and the core.

Notice the pressure gauge peeking out at the bottom of the tank on the left.

We've been using one of the tanks for our espar heater since last winter.

Cheers.
Paul.

[GordMay]

Originally Posted by DeepFrz

West Systems has a must read article (IMO) on building fiberglass/epoxy tanks. It's on their web site.

“... All types and variations of tanks have been successfully constructed with WEST SYSTEM® Brand epoxy and used in the field with great results. However, Gougeon Brothers does not condone or recommend that certain tanks be built because of various issues noted above. In our testing, various epoxy combinations have proven to be resistant to various liquids, including gasoline, diesel fuel, motor oil, potable water, sea water, sewage, gray water, etc...” ➥ WEST SYSTEM | Modifying and Customizing Boats - Wood/epoxy composite tank guidelines

ABYC Standard H-33-Diesel Fuel Systems
➥ http://newboatbuilders.com/docs/H-33_Diesel_2005.pdf

[GRIT]

Thanks Gord. I should have posted that.

I'm not going to re-read the rules, but here are a few points:

If I remember correctly, ABYC gives more leeway for tanks that are "built-in", which is why ours are thoroughly glassed to the hulls, which makes them "built-in".

I believe the primary problem was the fire test, but as "built-in" tanks don't have to pass that test, it's the best option for home builders building their own tanks.

Also, if it's a gasoline tank, you must have all fittings on the top. For diesel, like ours, you can have fittings anywhere.

Cheers, and good luck.
Paul.