"Ned Simmons" wrote in message
...
On Thu, 09 Feb 2012 19:28:51 -0600, Robert Nichols
wrote:

On 02/09/2012 12:13 PM, Jim Wilkins wrote:
"Stanley wrote

Both are tapered, at least the ones I have on hand are. Make sure
what you have, there's a straight series as well. ...
Stan

Outside of hydraulics I've seen straight pipe-sized threads only on
screw-in
water heater elements and shower head adapters.

Electrical conduit & fittings and lamp parts are NPS.

Conduit uses a tapered male thread; female threads on conduit fittings
are generally NPS.
Ned Simmons

I'm fairly sure I've seen both straight and tapered, depending on if it was
indoor or liquid-tight, cast metal or plastic box. The plastic imitation
Sealtite that Lowe's sells uses straight male threads and an O ring. I don't
have other samples handy to check.

I should have qualified my statement with "plumbing" though he's not likely
to use an electrical conduit fitting on the radiator.

jsw