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A blind flange is the part that shuts a line. It is a solid disc with no bore, bolted to a mating flange so the pipe, valve or nozzle behind it is sealed off. When that line carries steam or hot process fluid, carbon steel is often not enough, and that is where alloy steel blind flanges come in. We make them from chrome moly forgings under ASTM A182 in grades F5, F9, F11, F22 and F91, so the closure keeps its strength at temperatures where plain carbon steel starts to creep.
Because there is no opening, the whole face takes the pressure and the disc bends towards the centre. That is why a blind flange is thicker than a weld neck or slip on flange of the same size and class. Solitaire Overseas supplies alloy steel blind flanges in Class 150 to 2500, with raised face, flat face and ring type joint facings to ASME B16.5. Every order carries a mill test certificate to EN 10204 3.1, and third party inspection can be arranged when your project asks for it. This page belongs to our wider range of alloy steel flanges.
| Parameter | Specification |
|---|---|
|
Material |
ASTM A182 or ASME SA182 F1, F5, F9, F11 Class 1, 2 and 3, F12, F22 Class 1 and 3, F91 |
|
Dimension Standards |
ASME B16.5 for NPS 0.5 to 24, ASME B16.47 Series A and B for NPS 26 to 60, MSS SP 44 |
|
Pressure Class |
Class 150, 300, 600, 900, 1500, 2500 |
|
Facing |
Raised Face (RF), Flat Face (FF), Ring Type Joint (RTJ) |
|
Types |
Plain blind, hub blind, spectacle blind, paddle spacer, RTJ blind with ring groove |
|
Testing |
Hardness test, PMI, impact test on request, hydrostatic test on request |
|
Certification |
Mill Test Certificate EN 10204 3.1, 3.2 on request, third party inspection on request |
| Grade | C | Mn | P max | S max | Si | Cr | Mo | Other |
|---|---|---|---|---|---|---|---|---|
|
F1 |
0.28 max |
0.60 - 0.90 |
0.045 |
0.045 |
0.15 - 0.35 |
Not specified |
0.44 - 0.65 |
None |
|
F5 |
0.15 max |
0.30 to 0.60 |
0.030 |
0.030 |
0.50 max |
4.0 to 6.0 |
0.44 to 0.65 |
Ni 0.50 max |
|
F9 |
0.15 max |
0.30 to 0.60 |
0.030 |
0.030 |
0.50 to 1.00 |
8.0 to 10.0 |
0.90 to 1.10 |
None |
|
F11 |
0.05 to 0.15 |
0.30 to 0.60 |
0.030 |
0.030 |
0.50 to 1.00 |
1.00 to 1.50 |
0.44 to 0.65 |
None |
|
F22 |
0.05 to 0.15 |
0.30 to 0.60 |
0.040 |
0.040 |
0.50 max |
2.00 to 2.50 |
0.87 to 1.13 |
None |
|
F91 |
0.08 to 0.12 |
0.30 to 0.60 |
0.020 |
0.010 |
0.20 to 0.50 |
8.0 to 9.5 |
0.85 to 1.05 |
V 0.18 to 0.25, Nb 0.06 to 0.10, N 0.030 to 0.070, Ni 0.40 max |
| Grade | Tensile Strength (MPa) | Yield Strength min (MPa) | Elongation min (percent) | Hardness (HBW) |
|---|---|---|---|---|
|
F1 |
485 min |
275 |
20 |
Add from ASTM A182 |
|
F11 Class 1 |
415 min |
205 |
20 |
Add from ASTM A182 |
|
F11 Class 3 |
515 min |
310 |
20 |
Add from ASTM A182 |
|
F5 |
485 min |
275 |
20 |
143 to 217 |
|
F9 |
585 min |
380 |
20 |
179 to 217 |
|
F11 Class 2 |
485 to 660 |
275 |
20 |
197 max |
|
F22 Class 1 |
415 min |
205 |
20 |
170 max |
|
F22 Class 3 |
515 min |
310 |
20 |
156 to 207 |
|
F91 |
620 min |
415 |
20 |
190 to 248 |
| Nominal Size |
Outside Diameter (OD) |
Min. Thickness (T) |
RF Dia. (R) |
No. of Bolt Holes | Diameter of Holes |
Bolt Circle (BC) |
SO Bore ID (SB) |
WN Bore ID (WB) |
Dia. Hub Base (HB) |
Dia. of Hub Top (HT) |
SO LTH (SL) |
WN LTH (WL) |
|
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
|
1&frasl |
2 |
3.50 |
0.38 |
1.38 |
4 |
0.62 |
2.38 |
0.88 |
0.62 |
1.19 |
0.84 |
0.56 |
1.81 |
|
3&frasl |
4 |
3.88 |
0.44 |
1.69 |
4 |
0.62 |
2.75 |
1.09 |
0.82 |
1.50 |
1.05 |
0.56 |
2.00 |
|
1 |
4.25 |
0.50 |
2.00 |
4 |
0.62 |
3.12 |
1.36 |
1.05 |
1.94 |
1.32 |
0.62 |
2.12 |
|
|
11&frasl |
4 |
4.62 |
0.56 |
2.50 |
4 |
0.62 |
3.50 |
1.70 |
1.38 |
2.31 |
1.66 |
0.75 |
2.19 |
|
11&frasl |
2 |
5.00 |
0.62 |
2.88 |
4 |
0.62 |
3.88 |
1.95 |
1.61 |
2.56 |
1.90 |
0.81 |
2.38 |
|
2 |
6.00 |
0.69 |
3.62 |
4 |
0.75 |
4.75 |
2.44 |
2.07 |
3.06 |
2.38 |
0.94 |
2.44 |
|
|
21&frasl |
2 |
7.00 |
0.81 |
4.12 |
4 |
0.75 |
5.50 |
2.94 |
2.47 |
3.56 |
2.88 |
1.06 |
2.69 |
|
3 |
7.50 |
0.88 |
5.00 |
4 |
0.75 |
6.00 |
3.57 |
3.07 |
4.25 |
3.50 |
1.12 |
2.69 |
|
|
31&frasl |
2 |
8.50 |
0.88 |
5.50 |
8 |
0.75 |
7.00 |
4.07 |
3.55 |
4.81 |
4.00 |
1.19 |
2.75 |
|
4 |
9.00 |
0.88 |
6.19 |
8 |
0.75 |
7.50 |
4.57 |
4.03 |
5.31 |
4.50 |
1.25 |
2.94 |
|
|
5 |
10.00 |
0.88 |
7.31 |
8 |
0.88 |
8.50 |
5.66 |
5.05 |
6.44 |
5.56 |
1.38 |
3.44 |
|
|
6 |
11.00 |
0.94 |
8.50 |
8 |
0.88 |
9.50 |
6.72 |
6.07 |
7.56 |
6.63 |
1.50 |
3.44 |
|
|
8 |
13.50 |
1.06 |
10.62 |
8 |
0.88 |
11.75 |
8.72 |
7.98 |
9.69 |
8.63 |
1.69 |
3.94 |
|
|
10 |
16.00 |
1.12 |
12.75 |
12 |
1.00 |
14.25 |
10.88 |
10.02 |
12.00 |
10.75 |
1.88 |
3.94 |
|
|
12 |
19.00 |
1.19 |
15.00 |
12 |
1.00 |
17.00 |
12.88 |
12.00 |
14.38 |
12.75 |
2.12 |
4.44 |
|
|
14 |
21.00 |
1.31 |
16.25 |
12 |
1.12 |
18.75 |
14.14 |
13.25 |
15.75 |
14.00 |
2.19 |
4.94 |
|
|
16 |
23.50 |
1.38 |
18.50 |
16 |
1.12 |
21.25 |
16.16 |
15.25 |
18.00 |
16.00 |
2.44 |
4.94 |
|
|
18 |
25.00 |
1.50 |
21.00 |
16 |
1.25 |
22.75 |
18.18 |
17.25 |
19.88 |
18.00 |
2.62 |
5.44 |
|
|
20 |
27.50 |
1.62 |
23.00 |
20 |
1.25 |
25.00 |
20.20 |
19.25 |
22.00 |
20.00 |
2.81 |
5.62 |
|
|
22 |
29.50 |
1.75 |
25.25 |
20 |
1.38 |
27.25 |
22.22 |
21.25 |
24.25 |
22.00 |
3.07 |
5.82 |
|
|
24 |
32.00 |
1.81 |
27.25 |
20 |
1.38 |
29.50 |
24.25 |
23.25 |
26.12 |
24.00 |
3.19 |
5.94 |
Alloy steel blind flanges are used to close pipeline ends and provide secure isolation in demanding industrial environments.
Solitaire Overseas also supplies alloy steel fittings in matching grades, helping buyers source compatible piping components from one supplier.
It closes the end of a pipe, valve or vessel nozzle. Chrome moly material holds pressure at temperatures where carbon steel weakens, and the flange unbolts for inspection.
F11 suits moderate heat, F22 handles higher steam duty, and F91 covers the hottest lines with a thinner section. Match the grade to your pipe, such as P11 or P22.
The blind flange is bolted, not welded, so it needs none itself. The mating weld neck flange or nozzle may need PWHT under your project code.
A slip on flange has a bore and slides over the pipe to be welded. A blind flange has no bore and closes the line, taking full pressure.
We supply alloy steel blind flanges in Class 150, 300, 600, 900, 1500 and 2500 to ASME B16.5, with raised face, flat face and ring type joint facings.
Each order ships with a mill test certificate to EN 10204 3.1. Type 3.2, PMI reports and third party inspection are available when your project requires them.
Contact Solitaire Overseas for expert guidance and the right alloy steel blind flange for your project, or send your enquiry here.