External British Pipe Threads (Whitworth Form) Table per. BS EN ISO 228

ISO Metric Hardware Engineering Data
Fastener and Screw / Bolt Design, Formula and Calculations

External Pipe Threads per. ISO 228-1, Pipe threads where pressure-tight joints are not made by the threads. These pipe threads are also known as Whitworth pipe threads.

External Pipe Threads per. ISO 228-1

Where:

D = Major Dia.internal thread
D1 = Minor Dia.internal thread
D2 = Pitch diameter internal thread
d = Major Dia.external thread
d1 = Minor Dia.external thread
d2 = Pitch diameter external thread
TD1 = Tolerance internal thread minor diameter
TD2 = Tolerance on the pitch diameter of the internal thread
Td = Tolerance on the major diameter of the external thread
TD2 = Tolerance on the pitch diameter of the external thread
P = Pitch
H = Height of the fundamental triangle of the thread
h = Height of the thread profile with rounded crests and roots

ISO Pipe Thread
Designation
Size x Pitch
TPI
External ISO Pipe Thread Design Chart
Class
Major Dia
Pitch Dia
Minor Dia
Max
Min
Max
Min
Max
Min
G 1/16
G7.723 x 0.907
28
A
7.723
7.509
7.142
7.035
6.561
-
G 1/16
G7.723 x 0.907
28
B
7.723
7.509
7.142
6.928
6.561
-
G 1/8
G9.728 x 0.907
28
A
9.728
9.514
9.147
9.040
8.566
-
G 1/8
G9.728 x 0.907
28
B
9.728
9.514
9.147
8.933
8.566
-
G 1/4
G13.157 x 1.337
19
A
13.157
12.907
12.301
12.176
11.445
-
G 1/4
G13.157 x 1.337
19
B
13.157
12.907
12.301
12.051
11.445
-
G 3/8
G16.662 x 1.337
19
A
16.662
16.412
15.806
15.681
14.950
-
G 3/8
G16.662 x 1.337
19
B
16.662
16.412
15.806
15.556
14.950
-
G 1/2
G20.955 x 1.814
14
A
20.955
20.671
19.793
19.651
18.631
-
G 1/2
G20.955 x 1.814
14
B
20.955
20.671
19.793
19.509
18.631
-
G 5/8
G22.911 x 1.814
14
A
22.911
22.627
21.749
21.607
20.587
-
G 5/8
G22.911 x 1.814
14
B
22.911
22.627
21.749
21.465
20.587
-
G 3/4
G26.441 x 1.814
14
A
26.441
26.157
25.279
25.137
24.117
-
G 3/4
G26.441 x 1.814
14
B
26.441
26.157
25.279
24.995
24.117
-
G 7/8
G30.201 x 1.814
14
A
30.201
29.917
29.039
28.897
27.877
-
G 7/8
G30.201 x 1.814
14
B
30.201
29.917
29.039
28.755
27.877
-
G 1
G33.249 x 2.309
11
A
33.249
32.889
31.770
31.590
30.291
-
G 1
G33.249 x 2.309
11
B
33.249
32.889
31.770
31.410
30.291
-
G 1 1/8
G37.897 x 2.309
11
A
37.897
37.537
36.418
36.238
34.939
-
G 1 1/8
G37.897 x 2.309
11
B
37.897
37.537
36.418
36.058
34.939
-
G 1 1/4
G41.91 x 2.309
11
A
41.910
41.550
40.431
40.251
38.952
-
G 1 1/4
G41.91 x 2.309
11
B
41.910
41.550
40.431
40.071
38.952
-
G 1 1/2
G47.803 x 2.309
11
A
47.803
47.443
46.324
46.144
44.845
-
G 1 1/2
G47.803 x 2.309
11
B
47.803
47.443
46.324
45.964
44.845
-
G 1 3/4
G53.746 x 2.309
11
A
53.746
53.386
52.267
52.087
50.788
-
G 1 3/4
G53.746 x 2.309
11
B
53.746
53.386
52.267
51.907
50.788
-
G 2
G59.614 x 2.309
11
A
59.614
59.254
58.135
57.955
56.656
-
G 2
G59.614 x 2.309
11
B
59.614
59.254
58.135
57.775
56.656
-
G 2 1/4
G65.71 x 2.309
11
A
65.710
65.276
64.231
64.014
62.752
-
G 2 1/4
G65.71 x 2.309
11
B
65.710
65.276
64.231
63.797
62.752
-
G 2 1/2
G75.184 x 2.309
11
A
75.184
74.750
73.705
73.488
72.226
-
G 2 1/2
G75.184 x 2.309
11
B
75.184
74.750
73.705
73.271
72.226
-
G 2 3/4
G81.534 x 2.309
11
A
81.534
81.100
80.055
79.838
78.576
-
G 2 3/4
G81.534 x 2.309
11
B
81.534
81.100
80.055
79.621
78.576
-
G 3
G87.884 x 2.309
11
A
87.884
87.450
86.405
86.188
84.926
-
G 3
G87.884 x 2.309
11
B
87.884
87.450
86.405
85.971
84.926
-
G 3 1/2
G100.33 x 2.309
11
A
100.330
99.896
98.851
98.634
97.372
-
G 3 1/2
G100.33 x 2.309
11
B
100.330
99.896
98.851
98.417
97.372
-
G 4
G113.03 x 2.309
11
A
113.030
112.596
111.551
111.334
110.072
-
G 4
G113.03 x 2.309
11
B
113.030
112.596
111.551
111.117
110.072
-
G 4 1/2
G125.73 x 2.309
11
A
125.730
125.296
124.251
124.034
122.772
-
G 4 1/2
G125.73 x 2.309
11
B
125.730
125.296
124.251
123.817
122.772
-
G 5
G138.43 x 2.309
11
A
138.430
137.996
136.951
136.734
135.472
-
G 5
G138.43 x 2.309
11
B
138.430
137.996
136.951
136.517
135.472
-
G 5 1/2
G151.13 x 2.309
11
A
151.130
150.696
149.651
149.434
148.172
-
G 5 1/2
G151.13 x 2.309
11
B
151.130
150.696
149.651
149.217
148.172
-
G 6
G163.83 x 2.309
11
A
163.830
163.396
162.351
162.134
160.872
-
G 6
G163.83 x 2.309
11
B
163.830
163.396
162.351
161.917
160.872
-

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