This article provides a list of 347 stainless steel forged caps and couplings, with a precise focus on their dimensional data as governed by the ASME B16.11 standard.
Dimensions of 347 Stainless Steel Caps
Caps are end-closure fittings, available in threaded or socket-weld types, designed to cap off pipes or fittings securely. Threaded caps feature NPT threads for easy installation, while socket-weld variants offer stronger, fillet-welded joints for high-pressure systems.
Dimensions follow ASME B16.11, with tables below in millimeters for clarity. Sizes range from DN 6 (1/8") to DN 100 (4").
Threaded Caps
|
NPS |
DN |
Length (E) |
End Wall Thickness (G Min) |
Minimum Length of Thread (B) |
|
1/8" |
6 |
19 |
4.8 |
6.7 |
|
1/4" |
8 |
25 |
4.8 |
10.2 |
|
3/8" |
10 |
25 |
4.8 |
10.4 |
|
1/2" |
15 |
32 |
6.4 |
13.6 |
|
3/4" |
20 |
35 |
6.4 |
13.9 |
|
1" |
25 |
38 |
9.7 |
17.3 |
|
1-1/4" |
32 |
44 |
9.7 |
18.0 |
|
1-1/2" |
40 |
44 |
9.7 |
18.4 |
|
2" |
50 |
48 |
11.2 |
19.2 |
|
2-1/2" |
65 |
60 |
12.7 |
28.9 |
|
3" |
80 |
64 |
12.7 |
30.5 |
|
4" |
100 |
76 |
15.7 |
33.0 |
These dimensions ensure adequate thread engagement for pressure retention, with tolerances of ±0.8 mm on lengths. For instance, a 1" NPS threaded cap with a 38 mm length provides a robust seal in thermal cycling applications.
Socket-Weld Caps
|
NPS |
DN |
Bore Diameter Socket (B) |
Depth Socket (J Min) |
Length (E) |
End Wall Thickness (G Min) |
|
1/8" |
6 |
10.9-10.7 |
9.5 |
19 |
4.8 |
|
1/4" |
8 |
14.3-14.0 |
9.5 |
25 |
4.8 |
|
3/8" |
10 |
17.7-17.4 |
9.5 |
25 |
4.8 |
|
1/2" |
15 |
21.9-21.5 |
12.5 |
32 |
6.4 |
|
3/4" |
20 |
27.2-26.9 |
12.5 |
35 |
6.4 |
|
1" |
25 |
34.0-33.7 |
15.5 |
38 |
9.7 |
|
1-1/4" |
32 |
42.7-42.3 |
15.5 |
44 |
9.7 |
|
1-1/2" |
40 |
48.8-48.4 |
15.5 |
44 |
9.7 |
|
2" |
50 |
61.1-60.7 |
19.0 |
48 |
11.2 |
|
2-1/2" |
65 |
73.9-73.4 |
19.0 |
60 |
12.7 |
|
3" |
80 |
89.8-89.3 |
22.5 |
64 |
12.7 |
|
4" |
100 |
115.1-114.5 |
25.5 |
76 |
15.7 |
Socket bores are precision-machined for slip-fit assembly, with minimum depths ensuring fillet weld strength. A 2" NPS socket-weld cap, for example, withstands high vibrations in turbine exhausts.
Dimensions of 347 Stainless Steel Couplings
Couplings connect two pipes end-to-end and are available as full couplings (joining equal sizes) or reducing couplings. Threaded couplings offer quick assembly, while socket-weld types deliver superior joint integrity for cyclic loading.
Per ASME B16.11, dimensions include outside diameter (A), length (F min for threaded, E min for socket-weld), and end wall thickness.
Threaded Full Couplings
|
NPS |
DN |
Outside Diameter (A) |
Minimum Length (F) |
Minimum Wall Thickness (G) |
|
1/8" |
6 |
16 |
19 |
3.2 |
|
1/4" |
8 |
19 |
25 |
3.2 |
|
3/8" |
10 |
22 |
25 |
3.2 |
|
1/2" |
15 |
28 |
32 |
4.1 |
|
3/4" |
20 |
35 |
35 |
4.3 |
|
1" |
25 |
44 |
38 |
5.0 |
|
1-1/4" |
32 |
57 |
44 |
5.3 |
|
1-1/2" |
40 |
64 |
44 |
5.6 |
|
2" |
50 |
76 |
51 |
7.0 |
|
2-1/2" |
65 |
92 |
64 |
7.7 |
|
3" |
80 |
108 |
64 |
8.9 |
|
4" |
100 |
140 |
76 |
11.2 |
Lengths provide sufficient thread for secure joints, with tolerances ±1.6 mm.
Socket-Weld Full Couplings
|
NPS |
DN |
Bore Diameter Socket (B) |
Depth Socket (J Min) |
Outside Diameter (D) |
Minimum Length (E) |
|
1/8" |
6 |
10.9-10.7 |
9.5 |
16 |
32 |
|
1/4" |
8 |
14.3-14.0 |
9.5 |
22 |
35 |
|
3/8" |
10 |
17.7-17.4 |
9.5 |
25 |
35 |
|
1/2" |
15 |
21.9-21.5 |
12.5 |
32 |
44 |
|
3/4" |
20 |
27.2-26.9 |
12.5 |
38 |
51 |
|
1" |
25 |
34.0-33.7 |
15.5 |
48 |
51 |
|
1-1/4" |
32 |
42.7-42.3 |
15.5 |
57 |
64 |
|
1-1/2" |
40 |
48.8-48.4 |
15.5 |
64 |
64 |
|
2" |
50 |
61.1-60.7 |
19.0 |
76 |
70 |
|
2-1/2" |
65 |
73.9-73.4 |
19.0 |
92 |
76 |
|
3" |
80 |
89.8-89.3 |
22.5 |
108 |
76 |
|
4" |
100 |
115.1-114.5 |
25.5 |
140 |
102 |
For half couplings and reducing types, dimensions scale accordingly, with custom options available.
ASME B16.11 Cap, Half-Coupling and Coupling
|
Nominal size |
End-to-end |
End-to-end |
Outside diameter |
End wall |
Length of thread |
|||||
|
DN |
NPS |
W |
P |
D |
G |
L5min |
L2min |
|||
|
3000 & 6000 |
3000 |
6000 |
3000 |
3000 |
3000 |
3000 |
||||
|
6 |
1/8 |
32 |
19 |
- |
16 |
22 |
4.8 |
- |
6.4 |
6.7 |
|
8 |
1/4 |
35 |
25 |
27 |
19 |
25 |
4.8 |
6.4 |
8.1 |
10.2 |
|
10 |
3/8 |
38 |
25 |
27 |
22 |
32 |
4.8 |
6.4 |
9.1 |
10.4 |
|
15 |
1/2 |
48 |
32 |
33 |
28 |
38 |
6.4 |
7.9 |
10.9 |
13.6 |
|
20 |
3/4 |
51 |
37 |
38 |
35 |
44 |
6.4 |
7.9 |
12.7 |
13.9 |
|
25 |
1 |
60 |
41 |
43 |
44 |
57 |
9.7 |
11.2 |
14.7 |
17.3 |
|
32 |
11/4 |
67 |
44 |
46 |
57 |
64 |
9.7 |
11.2 |
17.0 |
18.0 |
|
40 |
11/2 |
79 |
44 |
48 |
64 |
76 |
11.2 |
12.7 |
17.8 |
18.4 |
|
50 |
2 |
86 |
48 |
51 |
76 |
92 |
12.7 |
15.7 |
19.0 |
19.2 |
|
65 |
21/2 |
92 |
60 |
64 |
92 |
108 |
15.7 |
19.0 |
23.6 |
28.9 |
|
80 |
3 |
108 |
65 |
68 |
108 |
127 |
19.0 |
22.4 |
25.9 |
30.5 |
|
100 |
4 |
121 |
68 |
75 |
140 |
159 |
22.4 |
28.4 |
27.7 |
33.0 |
ASME B16.11 SW Coupling, Half Coupling and Cap
|
Nominal size |
Socket bore diameter |
Bore diameter of fittings |
Socket wall thickness |
Body wall |
Min. Depth |
Laying lengths |
Laying lengths |
End Wall thickness |
Center to bottom of socket |
|||||||||||||||
|
DN |
NPS |
B |
D |
C |
Gmin |
Jmin |
E |
F |
Kmin |
A |
H |
|||||||||||||
|
3000 |
6000 |
9000 |
3000 |
6000 |
9000 |
3000 |
6000 |
9000 |
3000 |
6000 |
9000 |
3000 |
6000 |
3000 |
6000 |
|||||||||
|
Avg |
Min |
Avg |
Min |
Avg |
Min |
|||||||||||||||||||
|
6 |
1/8 |
10.9 |
6.1 |
3.2 |
- |
3.18 |
3.18 |
3.96 |
3.43 |
- |
- |
2.41 |
3.15 |
- |
9.5 |
6.5 |
16.0 |
4.8 |
6.4 |
- |
- |
- |
- |
- |
|
8 |
1/4 |
14.3 |
8.5 |
5.6 |
- |
3.78 |
3.30 |
4.60 |
4.01 |
- |
- |
3.03 |
3.68 |
- |
9.5 |
6.5 |
16.0 |
4.8 |
6.4 |
- |
- |
- |
- |
- |
|
10 |
3/8 |
17.7 |
11.8 |
8.4 |
- |
4.01 |
3.50 |
5.03 |
4.37 |
- |
- |
3.20 |
4.01 |
- |
9.5 |
6.5 |
17.5 |
4.8 |
6.4 |
- |
37 |
- |
9.5 |
- |
|
15 |
1/2 |
21.9 |
15.0 |
11.0 |
5.6 |
4.67 |
4.09 |
5.97 |
5.18 |
9.53 |
8.18 |
3.73 |
4.78 |
7.47 |
9.5 |
9.5 |
22.5 |
6.4 |
7.9 |
11.2 |
41 |
51 |
9.5 |
11 |
|
20 |
3/4 |
27.3 |
20.2 |
14.8 |
10.3 |
4.90 |
4.27 |
6.96 |
6.04 |
9.78 |
8.56 |
3.91 |
5.56 |
7.82 |
12.5 |
9.5 |
24.0 |
6.4 |
7.9 |
12.7 |
51 |
60 |
11 |
13 |
|
25 |
1 |
34.0 |
25.9 |
19.9 |
14.4 |
5.69 |
4.98 |
7.92 |
6.93 |
11.38 |
9.96 |
4.55 |
6.35 |
9.09 |
12.5 |
12.5 |
28.5 |
9.6 |
11.2 |
14.2 |
60 |
71 |
13 |
16 |
|
32 |
11/4 |
42.8 |
34.3 |
28.7 |
22.0 |
6.07 |
5.28 |
7.92 |
6.93 |
12.14 |
10.62 |
4.85 |
6.35 |
9.70 |
12.5 |
12.5 |
30.0 |
9.6 |
11.2 |
14.2 |
71 |
81 |
16 |
17 |
|
40 |
11/2 |
48.9 |
40.1 |
33.2 |
27.2 |
6.35 |
5.54 |
8.92 |
7.80 |
12.70 |
11.12 |
5.08 |
7.14 |
10.15 |
12.5 |
12.5 |
32.0 |
11.2 |
12.7 |
15.7 |
81 |
98 |
17 |
21 |
|
50 |
2 |
61.2 |
51.7 |
42.1 |
37.4 |
6.93 |
6.04 |
10.92 |
9.50 |
13.85 |
12.12 |
5.54 |
8.74 |
11.07 |
16.0 |
19.0 |
41.0 |
12.7 |
15.7 |
19.0 |
98 |
151 |
21 |
30 |
|
65 |
21/2 |
73.9 |
61.2 |
- |
- |
8.76 |
7.62 |
- |
- |
- |
7.01 |
- |
- |
16.0 |
19.0 |
43.0 |
15.7 |
19.0 |
- |
151 |
- |
30 |
- |
|
|
80 |
3 |
89.9 |
76.4 |
- |
- |
9.52 |
8.30 |
- |
- |
- |
7.63 |
- |
- |
16.0 |
19.0 |
44.5 |
19.0 |
32.4 |
- |
184 |
- |
57 |
- |
|
|
100 |
4 |
115.5 |
100.7 |
- |
- |
10.69 |
9.35 |
- |
- |
- |
8.56 |
- |
- |
19.0 |
19.0 |
48.0 |
22.4 |
28.4 |
- |
201 |
- |
66 |
- |
|
Pressure Ratings and Application
The allowable pressure rating of a fitting is a function of its class, material, and temperature. For 347 Stainless Steel under B16.11:
Threaded fittings are commonly available in 2000, 3000, and 6000 lb pressure classes.
Socket weld fittings are typically rated for higher pressures, commonly 3000, 6000, and 9000 lbs.
Selection must align with the system's design pressure and temperature. Furthermore, these fittings are designed for services where their specific material properties are needed:
High-Temperature Steam Lines: Where resistance to scaling and oxidation is required.
Refinery and Petrochemical Processes: Particularly in heater tubes and piping subjected to cyclic heating.
Power Plant Piping: In sections exposed to continuous high temperatures.
I hope this technical guide provides a clear and rigorous overview of 347 stainless steel caps and couplings. Should you require more detailed information on a specific pressure class size or have questions about their application in a particular service, please feel free to ask.
