GENERAL HYDRAULIC SYSTEM REPAIR - Continued
Do not apply sealant to the leading edge or the first thread of hydraulic fitting, or sealant may
get into the hydraulic system and contaminate it. Failure to comply may result in damage to
National Pipe Thread (NPT) is commonly found in hydraulic systems. It differs from other fittings because it is
tapered. In order to obtain a proper seal with this thread, you must use a sealant. The sealant should be applied
to the male fitting (Figure 1). Torque value guide is NOT to be used.
DO NOT APPLY
NATIONAL PIPE THREAD (NPT)
National Pipe Thread (NPT) Fittings.
The 37 degree flare termination has a male straight thread that mates with a female straight thread. The sealing
surface for this termination is the angled nose at the end of the male fitting. This nose mates with a similar
surface in the female 37 degree flare fitting (Figure 2). These sealing surfaces must be free of nicks and
scratches in order to seal properly. If nicked or scratched, item must be replaced. For torque requirements,
see guide in appendix.
37º FLARE NUT
Figure 2. 37 Degree Flare Termination Fitting.