Date Published:Jun. 18. 2015

Taper Pipe Threads

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Taper Pipe Threads

Basic profile, formula and basic dimensions of taper pipe threads

Basic profile applicable to taper male screws and taper female screws

Fitting of taper male screw with taper female screw or parallel female screw

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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