Page 417 - 4300 Catalog Cover.pdf

4300 Catalog Assembly / Installation
Parker Hannifin Corporation
Tube Fittings Division
Columbus, Ohio
http://www.parker.com/tfd
T7
The variety of thread forms available under taper threads in-
clude:
NPT – American Standard Taper Pipe Thread (ANSI B1.20.1).
NPTF – Dryseal American Standard Taper Pipe Thread (SAE
J476, ANSI B1.20.3).
BSPT or JIS “PT” – British Standard Pipe, Tapered (BS21,
JIS B 0203, ISO 7), also known as “R” for male and “Rc” for
female.
M-Keg – Metric taper threads (DIN 158).
The vast majority of ParkerTubeFittingsDivision’s standard pipe
thread fittings are machined with the NPTF thread form. NPTF
thread is also referred to as Dryseal Pipe Thread.
The full threadprofile contact of NPTF threads is designed togive
the tapered threads self-sealing ability without thread sealant.
However, variations in condition of mating threads, fitting and
port materials, assembly procedures and operating conditions
make self-sealing highly improbable. Some type of thread seal-
ant is, therefore, required to achieve proper seal and, in some
cases, additional lubricity to prevent galling.
Types of Sealant/Lubricant
Sealant/Lubricants assist in sealing and provide lubrication
during assembly, reducing the potential for galling. Pipe thread
sealants are available in various forms such as dry pre-applied,
tape, paste and anaerobic liquid.
Pre-applied sealants, suchas “Vibraseal” (registered trade-mark
of Loctite Corporation) and powdered PTFE are usually applied
to connectors by the manufacturer. Connectors with some of
these sealants may be remade a few times without needing
additional sealant. Vibraseal may also help reduce loosening
due to vibration.
PTFE tape, if not applied properly, can contribute to system
contamination during assembly and installation. In addition,
because of PTFE’s high lubricity, fittings can bemore easily over
tightened; and it does not offer much resistance to loosening
due to vibration.
Paste sealants can also contribute to system contamination,
if not applied properly. They are also messy to work with; and
some types require a cure period after component installation,
prior to system start up.
Anaerobic liquids are available from several manufacturers and
perform sealing as well as thread locking functions. They are
applied to the connectors by the user and require a cure period
prior to system start up. Some are soluble in common hydraulic
fluidsandwill not contaminate thesystem.Forproperperformance
they need to be applied to clean and dry components, carefully
following the manufacturer’s directions.
Tapered Thread Port Assembly
The proper method of assembling tapered threaded connectors
is to assemble them finger tight and then wrench tighten further
to the specifiednumber of turns fromfinger tight (T.F.F.T.) given in
TableT5.The following assembly procedure is recommended to
minimize the risk of leakage and/or damage to components.
1. Inspect components to ensure that male and female port
threads and sealing surfaces are free of burrs, nicks and
scratches, or any foreign material.
2. Apply sealant/lubricant to male pipe threads if not pre-ap-
plied. For stainless steel fittings, the use of Parker Thread-
mate sealant/lubricant is strongly recommended. (Pre-ap-
plied dry sealants are preferred over other sealants). With
any sealant, the first one to two threads should be left
uncovered to avoid system contamination. If PTFE tape
is used it should be wrapped 1-1/2 to 2 turns in clockwise
direction when viewed from the pipe thread end.
Caution: More than two turns of tape may cause distortion
or cracking of the port.
3. Screw the connector into the port to the finger tight posi-
tion.
4. Wrench tighten the connector to the appropriate T.F.F.T.
values shown in Table T5,making sure that the tube end of
a shaped connector is aligned to receive the incoming tube
or hose assembly. Never back off (loosen) pipe threaded
connectors to achieve alignment.
5. If leakage persists after following the above steps, check
for damaged threads and total number of threads engaged.
If threads on the fitting are badly nicked or galled, replace the
fitting. If port threads are damaged, re-tap, if possible, or replace
the component. If the port is cracked, replace the component.
Normally, the total number of tapered threads engaged should
be between 3-1/2 and 6. Any number outside of this range may
indicate either under or over tightening of the joint or out of toler-
ance threads.If the joint isunder tightened, tighten it further but no
more than one full turn. If it is over tightened, check both threads,
and replace the part which has out-of-tolerance threads.
As a general rule, pipe fittings with tapered threads should not
be assembled to a specific torque because the torque required
for a reliable joint varies with thread quality, port and fitting
materials, sealant used, and other factors. Where many of
these factors are well-controlled, such as particular jobs on an
assembly floor, a torque range that produces the desired results
may be determined by test and used in lieu of turns count for
proper joint assembly.
Port End Assembly
Table T5 – Assembly Turns From
Finger Tight (T.F.F.T) Values For
Steel, Stainless Steel and Brass Pipe
Fittings
Tapered Pipe
Thread Size
T.F.F.T. BSPT NPTF
1/8-28 1/8-27 2 - 3
1/4-19 1/4-18 2 - 3
3/8-19 3/8-18 2 - 3
1/2-14 1/2-14 2 - 3
3/4-14 3/4-14 2 - 3
1-11 1-11 1/2 1.5 - 2.5
1 1/4-11 1 1/4-11 1/2 1.5 - 2.5
1 1/2-11 1 1/2-11 1/2 1.5 - 2.5
2-11 2-11 1/2 1.5 - 2.5
Dimensions and pressures for reference only, subject to change.