| N.P.T. |
American Standard Taper Pipe Thread. |
| N.P.T.F. |
Dryseal American Standard Taper Pipe Thread. |
| P.T.F. |
Same as N.P.T.F. except full thread length has been shortened by one thread on small end of thread—also designated as P.T.F-SAE Short. |
| P.T.F Special Short |
Same as N.P.T.F Short except one full thread has been shortened from large end of thread. |
| P.T.F Special Extra Short |
Same as P.T.F Short except two full threads have been shortened from large end of thread. |
| N.P.S.F. |
Dryseal American Fuel Internal Straight Pipe Thread. |
| N.P.S.I. |
Dryseal American Intermediate Internal Straight Pipe Thread. |
| N.P.S.M. |
American Standard Straight Mechanical Pipe Thread. |
| 1/4″-28 Taper Thread (SAE-LT) |
Thread has a 3/4″ taper per foot and a pitch diameter of .2257 / .2224 at small end. The mating tapped hole is 1/4″-28 U.N.F. 3B straight thread. Tap drill must not exceed .215″ diameter. |
| 1/4″-28 Special Taper Drive Thread |
Thread Forming—Forms thread in mating part during installation—when removed can be replaced by standard 1/4″-28 taper thread (SAE-LT) fitting. |
| 1/8″ Pipe Special Taper Drive Thread |
Thread Forming—Forms thread in mating part during installation—when removed can be replaced by standard 1/8″-27 P.T.F series fitting. |
