Fuel Tank Acces Ports

[Joli]

Might want to consider making the threading blind on your retaining ring. Diesel seems to find a way to wick up the thread no matter what.

[Charlie]

Thanks Gord
Joli what is a blind thread?

[GordMay]

A Blind Fastening is one that does not penetrate through the host (substrate) material.
A Blind thread is cut with a Bottoming tap, wherein the thread stops short of penetrating the backer. The bolt goes into to the threaded backer, but does not penetrate to the inside, obviating the requirement for a sealant (there is no through hole).

[Charlie]

Thanks again Gord. I assume that will require a special bit and tap. I don't know if it would work on a 1/4" plate. Don't think there would be enough threads.

[GordMay]

Yes, square ended "bottoming" taps are required.

I think you’re right.
Notwithstanding, that an access plate might be an unloaded (static) fastening application, I would still recommend 5 full threads of engagement.
Hence, a ¼-20 bolt should be threaded at least ¼” deep, which precludes a “blind” fastening in ¼” plate. In this application, you'd have to rely upon a sealant.

[Joli]

As Gord mentioned, use a bottom tap. Maybe go up in material thickness to 3/8 or 1/2" for your base?

Originally Posted by GordMay

Yes, square ended "bottoming" taps are required.

I think you’re right.
Notwithstanding, that an access plate might be an unloaded (static) fastening application, I would still recommend 5 full threads of engagement.
Hence, a ¼-20 bolt should be threaded at least ¼” deep, which precludes a “blind” fastening in ¼” plate. In this application, you'd have to rely upon a sealant.

[Pblais]

I noticed that the commercial port uses Buna N material for the gasket. This is the better choice over sealant. It makes it possible to reseal the tank with the same gasket. Given at some point down the road you will of course open it up and you will need to close it too. bet you won't have replacement sealant handy then? It's 100% suited for fuel and you can buy the material yourself. Try McMaster-Carr

[Charlie]

Someone on th forum PMed me with a different idea. Instead of working inside the tank with 1/4" plate he suggexted working outside of the tank with 3/4 x 1 stock. From there I would use Joli's idea of blind threading.

1) Drill holes every 1/2 on alternate side of the 3/4 x 1 stock. Blind tap (?) all the holes on both sides of the stock. (Thanks Joli)

2) Weld stock into a rectangle. (thanks Pat)

3) cut access hole in tank.

4) Drill holes in the tank aligned with tapped holes on the bottom of the rectangle of 3/4 x 1 stock

5) apply permatex to the bottom of rectangle and then fasten to the outside of the tank. (thanks David M and Gord)

6) Cut plate to cover rectangle with holes drilled so that they are aligned with tapped holes on top of rectangle.

7) Use Buna N material as gasket. Then fasten plate to cover rectangle. (thanks Paul)
Wow what a great team effort. Thanks for all the help and advice

[Pblais]

Sounds like plan. We will be out in the morning to complete the job. You will require a large quantity of beer to test the tank.

[Charlie]

Sounds good Paul. I will probably need to get a keg of that really good PNW Beer and we can test a prototype on the aluminum keg to verify we have drank every last drop.

[delmarrey]

Originally Posted by Charlie

Someone on th forum PMed me with a different idea. Instead of working inside the tank with 1/4" plate he suggexted working outside of the tank with 3/4 x 1 stock. From there I would use Joli's idea of blind threading.

1) Drill holes every 1/2 on alternate side of the 3/4 x 1 stock. Blind tap (?) all the holes on both sides of the stock. (Thanks Joli)

2) Weld stock into a rectangle. (thanks Pat)

3) cut access hole in tank.

4) Drill holes in the tank aligned with tapped holes on the bottom of the rectangle of 3/4 x 1 stock

5) apply permatex to the bottom of rectangle and then fasten to the outside of the tank. (thanks David M and Gord)

6) Cut plate to cover rectangle with holes drilled so that they are aligned with tapped holes on top of rectangle.

7) Use Buna N material as gasket. Then fasten plate to cover rectangle. (thanks Paul)
Wow what a great team effort. Thanks for all the help and advice

That will work too! the only down fall is your trying to line up the bolts thru the rubber and twisting the rubber as the bolt goes in unless the rubber has an over size clearance hole. The industry has pretty much went with the studs sticking out routine unless it is a deck hatch where people have to walk over it.

Either way works!

PS: Buy the Red Hook

[Charlie]

Hi Del:

Red Hook. One of my favorites. I had this nagging feeling I was forgetting someone when I wrote that last post. And Now I know who. Thanks for your input. I thought studs would be easier maybe I should buy all thread (for the top) rather than bolts to make it work.