Hydraulic Hose
The tightening torques for union joints and union adaptors with parallel pipe threads (G, PF) are
shown in the table below.
A union joint or adaptor will not become loose or leak as long as it is tightened by the specified
torque.
If fluid leaks from the sealed portion, do not attempt to tighten the union joint or adaptor forcibly.
Examine whether any foreign matter or scratches are present on the seat surface.
Tightening a union joint or adaptor forcibly could damage the connection of the joints.
When tightening a union joint or adaptor, use a torque wrench where possible and firmly tighten it by
an appropriate torque.
Nominal diameter of
the hose size
Nominal diameter of
the parallel pipe
threads (G, PF)
Tightening torque
N-m
kgf-cm
lb-in
6
1/4
24.50
250
221.28
9
3/8
49.03
500
564.91
12
1/2
58.84
600
677.89
15
3/4
117.68
1200
1,355.78
19
3/4
117.68
1200
1,355.78
25
1
137.30
1400
1,581.74
32
1-1/4
166.72
1700
1,920.69
38
1-1/2
205.94
2100
2,372.61
50
2
245.17
2500
2,824.54
Fittings with Parallel Threads (O-Ring Seal Type)
The tightening torques for fittings with parallel threads (O-ring seal method) are shown in the table
below.
Tightening the fitting forcibly with a spanner or other such tool to secure it to a set position could
damage the fitting, its washers, and other parts. Be sure to tighten the fitting to the torque
appropriate to its size.
Nominal diameter
of thread
Tightening torque
N-m
kgf-cm
lb-in.
1/4
34.32 - 49.03
350 - 500
309.79 - 442.55
3/8
68.65 - 78.45
700 - 800
619.57 - 708.08
1/2
98.07 - 117.68
1000 - 1200
885.10 - 1,062.12
3/4
147.10 - 176.52
1500 - 1800
1,327.65 - 1,593.18
1
245.17 - 274.59
2500 - 2800
2,212.75 - 2,478.28
1-1/4
294.20
3000
2,655.30
1-1/2
294.20
3000
2,655.30
2
392.27
4000
3,540.40
LM311
Appended Table
Page 6-4
Tightening Torques
