[SEL] NPT taps

[Judge Tommy Turner]

Rick,

    Part of this would depend on if you threaded the pipe yourself or 
purchased one already threaded.  If you thread yourself, then you also 
have to determine how far up to thread (and if you're like me and have 
an adjustable set of pipe dies, it really can make you scratch your 
head).  A thread you make will sometimes have a slightly larger diameter 
than a "factory thread".   I usually run the tap 1/2 way in.  Since pipe 
threads are tapered, as long as you are able to get 4 to 5 threads 
started good and then are able to tighten the pipe without "bottoming 
out" the treads on it, you're in good shape.  Another key is to always 
use teflon tape.  One it will seal the treads and two, it sure makes 
taking this stuff apart easier after its been setting for 10 years.  If 
you are sealing gasoline, natural gas, or propane, be sure the teflon 
tape is suitable for that use.

Tommy Turner
Magnolia, KY


Ron Frost, Kersey, PA wrote:

>Good question Rick.  Can't tell you just how far it should go in, but a professional pipefitter told me once that you should be able to ingage a pipe thread into its fitting 4 to 5 turns by hand to get a proper seal. I guess you could fit and try until you got the 4-5 turns then check the tap to see just how many threads are showing.
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