Introduction
01-20
79033093 D Rev.
TIGHTENING STRAIGHT THREAD
FITTINGS
Straight thread hydraulic fittings require precise
tightening. Overtightening ruins sealing surfaces and
require replacement of damaged parts.
Proper initial tightening depends on mating parts to be
connected. Proceed as follows:
An adapter fitting (37 degree flare) connected to a double
flare tube assembly, fitting must be tightened finger tight
and wrenched 1/2 turn (for single flare, 1/4 turn).
An adapter fitting (37 degree flare) connected to a hose,
fitting must be tightened finger tight and wrenched 1/4
turn.
An o-ring adapter fitting connected to a solid port, fitting
must be tightened so backup washer contacts face of
boss after fitting has been properly positioned.
To retighten after initial tightening, as in service work, both
tube and hose connnections should be tightened finger
tight and wrenched 1/4 turn. O-ring fittings should be
tightened as for initial assembly.
JIC SWIVEL NUTS (37 degree SEAT). Following values
are maximum recommended torque values for JIC (37
degree seat) swivel nuts either swaged or brazed type.
Swivel nuts normally withstand torque for a minimum of
15 repeated assemblies.
Torque required to seal swivel female fittings or hose
couplings to a male connector depends on many
variables such as medium, pressure, surface finish, etc.
Following values are intended only as a guide for
maximum values fittings may be subjected to.
DASH SIZE
TUBE O. D.
(REF.)
TORQUE MAX
Nm
lbf in
lbf ft
-4
1/4
12
110
9
-5
5/16
20
180
15
-6
3/8
27
240
20
-8
1/2
40
360
30
-10
5/8
54
480
40
-12
3/4
95
840
70
-14
7/8
110
980
80
-16
1
120
1080
90
-20
1 1/4
160
1440
120
-24
1 1/2
180
1575
130
-32
2
400
3600
300
-40
2 1/2
540
4800
400
-48
3
680
6000
500
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