On Oct 4, 10:45*pm, matt_colie wrote:
Tom Dacon wrote:
What's your favorite diesel-resistant gasket sealant?

*This is for the nitrile gasket on a clean-out port on the top ofa small diesel fuel tank.
I wouldn't mind something that worked well for pipe threads, too.

Thanks,
Tom Dacon

Tom,
Why do you think it needs a sealant in addition to the gasket.
If you are having a distinct problem with the assembly,
there may be some other issue here.
Matt

Most threaded connections is a fuel system shouldnt ever need gaskets,
sealants, etc. Compression fittings, double flared fittings, etc.
are *dry* metal to metal 'ring sealed', and the 'threads' on these are
ONLY to apply force to the rings seal (compression faces). So, if you
need to seal such fitting with goo/glop/dope, etc. then you have a BAD
fitting or a fitting that is worn-out .... and you should replace the
fitting in its entirety.

Compression fittings are designed for 'one time tighten only' and if
you need to open and reconnect you 'should' cut off the tubing area
that the 'compression ferrule' fits and put the compression ferrule
back onto 'uncompressed' (copper) tube; copper tube deforms under
these ferrules and you 'should' always cut off any part of the tube
that WAS previously compressed.

Double flared fittings can be opened/retightened, etc. many times;
and, should be the 'choice' for boat installations.

On Mon, 5 Oct 2009 06:49:06 -0700 (PDT), RichH
wrote:

On Oct 4, 10:45*pm, matt_colie wrote:
Tom Dacon wrote:
What's your favorite diesel-resistant gasket sealant?

*This is for the nitrile gasket on a clean-out port on the top ofa small diesel fuel tank.
I wouldn't mind something that worked well for pipe threads, too.

Thanks,
Tom Dacon

Tom,
Why do you think it needs a sealant in addition to the gasket.
If you are having a distinct problem with the assembly,
there may be some other issue here.
Matt

Most threaded connections is a fuel system shouldnt ever need gaskets,
sealants, etc. Compression fittings, double flared fittings, etc.
are *dry* metal to metal 'ring sealed', and the 'threads' on these are
ONLY to apply force to the rings seal (compression faces). So, if you
need to seal such fitting with goo/glop/dope, etc. then you have a BAD
fitting or a fitting that is worn-out .... and you should replace the
fitting in its entirety.

Compression fittings are designed for 'one time tighten only' and if
you need to open and reconnect you 'should' cut off the tubing area
that the 'compression ferrule' fits and put the compression ferrule
back onto 'uncompressed' (copper) tube; copper tube deforms under
these ferrules and you 'should' always cut off any part of the tube
that WAS previously compressed.

Double flared fittings can be opened/retightened, etc. many times;
and, should be the 'choice' for boat installations.

That's fine for gasoline engines but many large diesels and their
external filtration systems used ordinary pipe threads. Diesel
mechanics routinely use something like blue Permatex goop to seal the
pipe threads. Supposedly teflon tape is a big no-no with diesel.

"matt_colie" wrote in message
...
Tom Dacon wrote:
What's your favorite diesel-resistant gasket sealant? This is for the
nitrile gasket on a clean-out port on the top of
a small diesel fuel tank. I wouldn't mind something that worked well for
pipe threads, too.

Thanks,
Tom Dacon

Tom,
Why do you think it needs a sealant in addition to the gasket.
If you are having a distinct problem with the assembly,
there may be some other issue here.
Matt

Matt, I don't actually KNOW that it needs a sealant in addition to the
gasket. The clean-out port is on top of the tank, and the seal would be only
under stress when the boat is operating in a heavy seaway, where the area
might be subject to impact loading from the fuel sloshing in the tank. The
tank's 316L CRES of either 12 or 16 gauge, so flexing is a possibility in
heavy conditions. The dynamic loads are difficult to determine, and my only
other practical way to test it would be to fill the tank, close off all the
plumbing fittings, and invert it. Even then I'd be applying only a static
load.

So I'm thinking that if I could run a small bead of sealant around the
gasket it might help in maintaining a good seal in those circumstances.
Couldn't hurt, might help, and if it does it'll help keep the smell of
diesel out of the living spaces.

Tom

"Wayne.B" wrote in message
...
On Mon, 5 Oct 2009 06:49:06 -0700 (PDT), RichH
wrote:


That's fine for gasoline engines but many large diesels and their
external filtration systems used ordinary pipe threads. Diesel
mechanics routinely use something like blue Permatex goop to seal the
pipe threads. Supposedly teflon tape is a big no-no with diesel.


Right - standard pipe threads, and this is the off-engine plumbing - fuel
transfer between tanks, etc.

Previously, I was using a teflon-based paste of some sort, but my supply is
long gone and I no longer remember what it was called or where I got it.
Hence my request for suggestions.

Tom

On Mon, 5 Oct 2009 08:54:08 -0700, "Tom Dacon"
wrote:

Previously, I was using a teflon-based paste of some sort, but my supply is
long gone and I no longer remember what it was called or where I got it.
Hence my request for suggestions.

Check with NAPA auto parts. Tell them it is for pipe threads with a
diesel fuel system.

On Mon, 5 Oct 2009 08:51:28 -0700, "Tom Dacon"
wrote:



So I'm thinking that if I could run a small bead of sealant around the
gasket it might help in maintaining a good seal in those circumstances.
Couldn't hurt, might help, and if it does it'll help keep the smell of
diesel out of the living spaces.

I look at Permatex first for this kind of thing.
This is probably what you're after.
http://www.permatex.com/documents/td...tive/85249.pdf

--Vic

Tom,
Loktite pipe sealer is Teflon based and I use it extensively for NPT joints in Diesel fuel systems. It is expensive though.
Steve

"Tom Dacon" wrote in message ...

"matt_colie" wrote in message
...
Tom Dacon wrote:
What's your favorite diesel-resistant gasket sealant? This is for the
nitrile gasket on a clean-out port on the top of
a small diesel fuel tank. I wouldn't mind something that worked well for
pipe threads, too.

Thanks,
Tom Dacon

Tom,
Why do you think it needs a sealant in addition to the gasket.
If you are having a distinct problem with the assembly,
there may be some other issue here.
Matt

Matt, I don't actually KNOW that it needs a sealant in addition to the
gasket. The clean-out port is on top of the tank, and the seal would be only
under stress when the boat is operating in a heavy seaway, where the area
might be subject to impact loading from the fuel sloshing in the tank. The
tank's 316L CRES of either 12 or 16 gauge, so flexing is a possibility in
heavy conditions. The dynamic loads are difficult to determine, and my only
other practical way to test it would be to fill the tank, close off all the
plumbing fittings, and invert it. Even then I'd be applying only a static
load.

So I'm thinking that if I could run a small bead of sealant around the
gasket it might help in maintaining a good seal in those circumstances.
Couldn't hurt, might help, and if it does it'll help keep the smell of
diesel out of the living spaces.

Tom

"Vic Smith" wrote in message
...
On Mon, 5 Oct 2009 08:51:28 -0700, "Tom Dacon"
wrote:



So I'm thinking that if I could run a small bead of sealant around the
gasket it might help in maintaining a good seal in those circumstances.
Couldn't hurt, might help, and if it does it'll help keep the smell of
diesel out of the living spaces.

I look at Permatex first for this kind of thing.
This is probably what you're after.
http://www.permatex.com/documents/td...tive/85249.pdf

--Vic

Whoo - that looks pretty good.

Thanks,
Tom

"Steve Lusardi" wrote in message
...
Tom,
Loktite pipe sealer is Teflon based and I use it extensively for NPT
joints in Diesel fuel systems. It is expensive though.
Steve


Thanks, Steve - I'll see what my local NAPA can do for me.

Tom

Tom Dacon wrote:
"matt_colie" wrote in message
...
Tom Dacon wrote:
What's your favorite diesel-resistant gasket sealant? This is for the
nitrile gasket on a clean-out port on the top of
a small diesel fuel tank. I wouldn't mind something that worked well for
pipe threads, too.

Thanks,
Tom Dacon

Tom,
Why do you think it needs a sealant in addition to the gasket.
If you are having a distinct problem with the assembly,
there may be some other issue here.
Matt

Matt, I don't actually KNOW that it needs a sealant in addition to the
gasket. The clean-out port is on top of the tank, and the seal would be only
under stress when the boat is operating in a heavy seaway, where the area
might be subject to impact loading from the fuel sloshing in the tank. The
tank's 316L CRES of either 12 or 16 gauge, so flexing is a possibility in
heavy conditions. The dynamic loads are difficult to determine, and my only
other practical way to test it would be to fill the tank, close off all the
plumbing fittings, and invert it. Even then I'd be applying only a static
load.

So I'm thinking that if I could run a small bead of sealant around the
gasket it might help in maintaining a good seal in those circumstances.
Couldn't hurt, might help, and if it does it'll help keep the smell of
diesel out of the living spaces.

Tom

Tom,

The problem is that if you put a pipe thread dressing on the gasket,
those things are all some manner of lubricant and may invite the gasket
to slide in the joint.

If you sue any type of dressing that is has adhesive properties (most
all that are not lubricants do), it may make future use of the access
port difficult at best. It may cause the gasket to be destroyed during
a future service.

Without seeing the situation, I'm afraid I can't be much more help than
that.

Matt