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Carbon steel blind flanges are solid, forged steel discs engineered without an inner bore, designed specifically to cap pipe ends, seal pressure vessel openings, and isolate fluid flow in high-pressure piping systems. Manufactured with high tensile strength and superior yield resistance, these flanges feature exceptional mechanical durability and are available in various facing configurations including Raised Face (RF), Ring Type Joint (RTJ), and Flat Face (FF). They strictly conform to dimensional standards such as ASME B16.5, ASME B16.47, EN 10921, and DIN specs, making them an economical and dependable sealing solution for demanding oil, gas, chemical, and industrial operations. Solitaire Overseas is a globally trusted manufacturer, stockist, and exporter of high-grade carbon steel flanges. We maintain a complete inventory ready for rapid worldwide delivery to meet your project specifications.
Request a Quote for Carbon Steel Flanges| Technical Parameter | Specification Details |
|---|---|
ASME / ANSI Standards |
ASME B16.5 (NPS 1/2 inch to 24 inch), ASME B16.47 Series A & B (NPS 26 inch to 60 inch) |
Pressure Classes |
Class 150, Class 300, Class 600, Class 900, Class 1500, Class 2500 |
European Standards |
EN 10921 Type 05, DIN 2527 |
Pressure Ratings (PN) |
PN6, PN10, PN16, PN25, PN40, PN64, PN100 |
Facing Types |
Raised Face (RF), Ring Type Joint (RTJ), Flat Face (FF), Male & Female (M&F), Tongue & Groove (T&G) |
Value Addition |
Custom drilling, NPT threaded tapings for instrument connections, galvanizing, black rust preventive coating, and epoxy lining |
| Element | ASTM A105 (Standard Temp) | ASTM A350 LF2 (Low Temp) | ASTM A694 F52 (High Yield) |
|---|---|---|---|
Carbon (C) max |
0.35 |
0.30 |
0.20 |
Manganese (Mn) |
0.60 to 1.05 |
0.60 to 1.35 |
1.35 max |
Phosphorus (P) max |
0.035 |
0.035 |
0.025 |
Sulfur (S) max |
0.040 |
0.040 |
0.025 |
Silicon (Si) |
0.10 to 0.35 |
0.15 to 0.30 |
0.15 to 0.35 |
Nickel (Ni) max |
0.40 |
0.40 |
0.50 |
Chromium (Cr) max |
0.30 |
0.30 |
0.30 |
Molybdenum (Mo) max |
0.12 |
0.12 |
0.12 |
| Mechanical Property | ASTM A105 | ASTM A350 LF2 Class 1 | ASTM A694 F52 |
|---|---|---|---|
Tensile Strength min |
485 MPa (70 ksi) |
485 to 655 MPa (70 to 95 ksi) |
455 MPa (66 ksi) |
Yield Strength min |
250 MPa (36 ksi) |
250 MPa (36 ksi) |
360 MPa (52 ksi) |
Elongation min % |
22% |
22% |
20% |
Reduction of Area min |
30% |
30% |
40% |
Impact Test Temp |
N/A |
minus 46°C (minus 50°F) |
N/A |
Hardness max (HBW) |
197 |
197 |
225 |
| Nominal Size (NPS) | Outside Dia (O) | Thickness (T) min | Raised Face Dia (G) | Bolt Circle Dia (C) | Number of Bolts | Bolt Hole Dia | Approx Weight (Kg) |
|---|---|---|---|---|---|---|---|
1/2 inch |
89 mm |
11.2 mm |
35.0 mm |
60.3 mm |
4 |
15.9 mm |
0.45 |
3/4 inch |
98 mm |
12.7 mm |
42.9 mm |
69.9 mm |
4 |
15.9 mm |
0.68 |
1 inch |
108 mm |
14.2 mm |
50.8 mm |
79.2 mm |
4 |
15.9 mm |
0.90 |
1.5 inch |
127 mm |
17.5 mm |
73.0 mm |
98.6 mm |
4 |
15.9 mm |
1.81 |
2 inch |
152 mm |
19.1 mm |
92.1 mm |
120.7 mm |
4 |
19.1 mm |
2.27 |
3 inch |
191 mm |
23.9 mm |
127.0 mm |
152.4 mm |
4 |
19.1 mm |
4.54 |
4 inch |
229 mm |
23.9 mm |
157.2 mm |
190.5 mm |
8 |
19.1 mm |
7.00 |
6 inch |
279 mm |
25.4 mm |
215.9 mm |
241.3 mm |
8 |
22.4 mm |
12.25 |
8 inch |
343 mm |
28.6 mm |
269.9 mm |
298.5 mm |
8 |
22.4 mm |
21.77 |
10 inch |
406 mm |
30.2 mm |
323.8 mm |
362.0 mm |
12 |
25.4 mm |
34.00 |
12 inch |
483 mm |
31.8 mm |
381.0 mm |
431.8 mm |
12 |
25.4 mm |
48.00 |
The carbon steel blind flange is a steel disk used to close up or seal the ends of pipes or flanges in a safe manner, so that there will be no flow of media during periodic maintenance.
The distinction between ASTM A105 and ASTM A350 LF2 is that ASTM A105 is made for both ambient and high-temperature applications, while ASTM A350 LF2 is a low-temperature impact-tested carbon steel which functions in subzero temperatures down to -46 degree Celcius.
For high-pressure blind flanges, the Ring Type Joint (RTJ) facing is recommended because the metal ring of the gasket creates a secure seal.
Yes, it is possible to drill holes in flanges for the installation of pressure gauge, venting of liquids, or drainage.
Carbon steel blind flanges are manufactured per ASME B16.5 for sizes up to 24 inches, ASME B16.47 for larger sizes, EN 10921, and DIN 2527 standards.
Forged flanges offer continuous grain flow, superior mechanical toughness, and higher pressure resistance, whereas plate-cut flanges risk internal lamination flaws under heavy stress.