NTP (National Taper Pipe?) uses an intereference-fit tapered
thread which will self-seal when threaded (Teflon(r) sealant
highly recommended). IMS, BSP (British Straight Pipe) uses
straight threads and crush washers to give a seal.
AN (Army/Navy) uses precision-machined fittings to provide
a self-sealing angled face joint.
Again, I highly recommend:
_Carroll Smith's Nuts, Bolts, Fasteners, and Plumbing Handbook_
(colloquially known as "Screw to Win"), Motorbooks International,
Osceola, WI, 1990. ISBN 0-87938-406-9
For those thinking of plumbing brake systems with SS braided
hose, the AN fittings use a 37 degree flare, while the standard
flare for brake lines is 45 degrees. Most race shops sell adapter
fittings, Carroll Smith also mentions an AN-spec "crush washer"
from Earl's that may be used to mate the different angles.
Dave Williamson (silikal@aol.com) Spits in bits
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