Dave wrote:

Resent.

Got it this time.

It's the same round threaded cap I'm familiar with, but the first time
I've ever seen any "ears" on it. I still have a couple in a box of
assorted odds and ends... I just took a look to make sure I hadn't
forgotten what they look like...no "ears" on them. The rubber
o-ring--which should be round (not just the round ring, but the rubber
"band" that is the ring) and about 1/4" thick--is what provides the
seal. We always just hand-tightened 'em...and never had a problem with
'em leaking, even when we pressure tested a tank to higher pressure than
is required.

But if you want to use a wooden mallet to tighten it a BIT more, it
can't hurt. Just don't overdo it...'cuz the more you flatten an o-ring
or gasket, the less sealing ability it has. And to answer your original
question...no, don't use any lubricant.

The following doesn't apply to an o-ring under the flange on a threaded
cap, but while I have the floor and we're on the subject of gaskets and
o-rings... If you over-tighten a rubber gasket between two pieces held
together with screws, you'll cause it to leak because it'll
"pucker"...people do it all the time when they replace a joker valve and
think that tightening it even more will solve the problem, when it does
just the opposite....makes the pucker even more pronounced, which causes
it leak even more. The right solution is to back it off till it stops
leaking.

--
Peggie
----------
Peggie Hall
Specializing in marine sanitation since 1987
Author "Get Rid of Boat Odors - A Guide To Marine Sanitation Systems and
Other Sources of Aggravation and Odor"
http://www.seaworthy.com/store/custo...0&cat=6&page=1
http://shop.sailboatowners.com/books...ku=90&cat=1304