Introduction
01-20
79026547 Rev. A
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° 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° 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° SEAT). Following values are
maximum recommended torque values for JIC (37° 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
N-m
lb-in
lb-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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