Taper Pipe Threads

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Taper Pipe Threads

Basic profile, formula and basic dimensions of taper pipe threads

Unit : mm

1
Nominal
Diameter of
Thread
Screw Thread Gauge diameter Gauge diameter position
Number of
screw
threads
(per 25.4㎜)
n
Pitch
P
(Reference)
Height of
screw
thread
Radius
r or r'
Male Screw Male Screw Female Screw
Outside
diameter
d
Effective
diameter
d2
Root
diameter
d1
From pipe end Pipe edge
Reference
length
a
Tolerance in
axial line
direction
b
Tolerance in
axial line
direction
c
Female Screw 
Root
diameter
D
Effective
diameter
D2
Inside
diameter
D1
R 1/16
R 1/8
R 1/4
28
28
19
0.9071
0.9071
1.3368
0.581
0.581
0.856
0.12
0.12
0.18
  7.723
  9.728
13.157
  7.142
  9.147
12.301
  6.561
  8.566
11.445
3.97
3.97
6.01
±0.91
±0.91
±1.34
±1.13
±1.13
±1.67
R 3/8
R 1/2
R 3/4
19
14
14
1.3368
1.8143
1.8143
0.856
1.162
1.162
0.18
0.25
0.25
16.662
20.955
26.441
15.806
19.793
25.279
14.950
18.631
24.117
6.35
8.16
9.53
±1.34
±1.81
±1.81
±1.67
±2.27
±2.27
R1
R1 1/4
R1 1/2
11
11
11
2.3091
2.3091
2.3091
1.479
1.479
1.479
0.32
0.32
0.32
33.249
41.910
47.803
31.770
40.431
46.324
30.291
38.952
44.845
10.39
12.70
12.70
±2.31
±2.31
±2.31
±2.89
±2.89
±2.89

1 This nominal diameter is for taper male screws. For taper female screws and parallel females screws, the symbol R shall be changed to RC or RP



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