Triple-Lok
®
and Triple-Lok
®
2
37
° Flare Tube Fittings
B6
Parker Hannifin Corporation
Tube Fittings Division
Columbus, Ohio
http://www.parker.com/tfd
4300
Catalog
Triple-Lok
Parker Triple-Lok fittings meet the strict requirements of SAE
J514 and ISO 8434-2 industry standards for 37° flare fittings.
Its design is simple. It uses an easily produced flare at the
tube end to seal and hold fluid under high pressure. The fitting
consists of three pieces: the body, sleeve and nut. The tube
is flared at a 37° angle (74° included angle) and held between
the fitting nose (seat) and the sleeve (support) with the nut as
shown in Fig. B1, providing a very effective seal between the
fitting nose and the tube flare.
The design of Triple-Lok fittings is very efficient. The fitting in-
corporates the smallest seal area of all fitting types. This seal
area, as seen in Fig. B1, is only slightly larger than the fluid
flow area. The small seal area results in a compact design,
low assembly torque, and a relatively high-pressure capability.
How Triple-Lok Fittings Work
Tightening of the nut clamps the tube flare between the body
nose (seat) producing a leak tight connection. This clamping on
the 37° taper provides a measure of elasticity to the joint helping
it to resist loosening under vibration. The clamping force results
in a small radial load that tends to deform the fitting nose radi-
ally. The resistance of the nose to elastic deformation provides
a constant preload (similar to a lockwasher) keeping it tight.
The clamping forceprovidedby thenut resists theopposing force
of the fluid under pressure. The joint remains leak tight as long
as the clamping force is higher than the opposing pressure load.
Properly assembled Triple-Lok fittings with appropriate tube will
seal consistently under pressure until tube bursts.
Sealing in Triple-Lok fittings takes place between two smooth
metal surfaces, the fitting nose and inside of the tube flare.
Therefore, the sealing surfaces have to be smooth, free of
any nicks, scratches, spiral tool marks, splits or weld beads.
Seamless or welded and drawn fully annealed tube is recom-
mended for Triple-Lok fittings for ease in flaring and bending.
Certain types of harder tubes that are not fully annealed may
not be suitable for flaring due to the potential for immediate or
long-term cracking of the tube flare. For specific tube type and
wall thickness recommendations, please see
Table U3
in the
Appendix Section.
Sleeve
Clamping and Seal-
ing Surface of tube
flare against body
nose
Flare Support
resisting “opening”
of flare
Bearing
Surface
Small seal area allows for
adequate clamping load
applied with relatively
low assembly torques
Fig. B1 – Triple-Lok Design and Features
Flared
Tube
Seal
International Acceptance
The versatility of 37° flare fittings is a primary reason for its
worldwide acceptance. To illustrate the versatility of Triple-Lok,
refer to Fig.B2.The Triple-Lok adapter is attachable to either inch
tube, metric tube, or a hose assembly. To adapt to metric tube,
simply change the sleeve (using the standard inch adapter and
nut). Please see
Table U4
in the
Appendix Section
for a clear
illustration of every “convertible sleeve” connection for the 37°
design. For example, for a 25 mm tube assembly, a standard
SAE -16 (1”) flare fitting and nut would be used, however, a 25
mm metric sleeve (TXS25) would replace the inch size sleeve.
Triple-Lokfittingsareavailablewithmanydifferent port options for
the various international hydraulic ports available, such as SAE
straight thread, NPT/NPTF, BSPP, BSPT and Metric (including
ISO 6149).
Inch Tube
Metric Tube
Hose Assembly
Fig. B2 – Triple-Lok’s Adaptability to Inch Tube, Metric Tube, or
Hose Assemblies
Inch
Sleeve
Metric
Sleeve
Universal
Tube Nut
Universal
Triple-Lok Body
link