Tim Williams wrote:

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"PhysicsGenius" wrote in message


I don't see why (or how) it wouldn't. Pipe threads are made to seal...
As-is, the high surface tension of aluminum would probably hold it in,

I'd side with you on the surface tension thing, but I gotta jump on your
statement that pipe threads "are made to seal..."

They're not, unless they're the somewhat rare "dryseal" or "fuel service"
thread form.

Regular NPT pipe threads cut to spec have a built in "spiral leak path" along
the crests of the threads, and won't seal under normal torquing unless some
sort of sealant, pipe dope or tape, is employed. A glance at the thread form
diagrams in Machinery's Handbook will confirm that.

The "dryseal" threads are made with a thread form which seals tight through
minor deformation of the metal parts. They are usually found on brass parts to
enable that to happen easily. They were developed back when the available pipe
dopes didn't stand up to petroleum products and solvents too well. Nowadays,
teflon tape will enable regular NPT threads to seal many of those fluids ok.

Just my .02,

Jeff


especially with a nice heavy layer of scale which you need to toast onto it
first anyway. (Try for a good orange heat over the whole thing, minimum.)
Aluminum just doesn't tend to flow through pores.
'Course, "probably" isn't good enough, so find some nice monkey wrenches,
tighten it up, toast it, see if that works.

Tim

--
"That's for the courts to decide." - Homer Simpson
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--
Jeff Wisnia (W1BSV + Brass Rat '57 EE)

"If you can keep smiling when things go wrong, you've thought of someone to
place the blame on."