Blind Flange — ASME B16.5
Also written BLRF
Blind flange — a solid disc that closes the end of a pipe, valve or vessel nozzle. Use a blind flange to terminate a line, close a nozzle for future connection, or allow pressure testing. It takes the full line pressure plus bolting load, so it is often the heaviest flange in a class.
- ASME B16.5
- 23 grades
- EN 10204 3.1 / 3.2
Reviewed by the Kanak Steel & Engineering Co. technical team · Updated October 2026
What is a blind flange?
A blind flange is a solid disc that closes the end of a pipe, valve or vessel nozzle. Use a blind flange to terminate a line, close a nozzle for future connection, or allow pressure testing. It takes the full line pressure plus bolting load, so it is often the heaviest flange in a class.
Standards for blind flanges
| Dimensions | ASME B16.5 · B16.47 · EN 1092-1 |
|---|---|
| Material — stainless & duplex | ASTM A182 (F304L, F316L, F904L, F51, F53) |
| Material — nickel alloys | ASTM B564 (825, 625, 600, Monel 400, C276) |
| Material — carbon steel | ASTM A105 · ASTM A350 LF2 for low temperature |
| Certificate | EN 10204 3.1, or 3.2 with third-party inspection |
Blind Flange: What to Know Before Ordering
- No bore; thickness set by the pressure class
- Can be drilled and tapped for an instrument connection
- Often cut from plate in large sizes or special alloys
Blind Flange Materials & Grades
| Grade | Material standard | Best for |
|---|---|---|
| Inconel 825 blind flange | ASTM B564 | Sulphuric and phosphoric acid service, chloride stress-corrosion cracking and sour gas |
| SS 904L blind flange | ASTM A182 F904L | Dilute sulphuric acid, phosphoric acid and chloride-bearing cooling water |
| SS 304 blind flange | ASTM A182 F304 | General corrosion resistance, food, water and architectural work |
| SS 304L blind flange | ASTM A182 F304L | Welded tanks, piping and vessels in general corrosive service |
| SS 310 / 310S blind flange | ASTM A182 F310 | Furnaces, burners and heat treatment at high temperature |
| SS 316 / 316L blind flange | ASTM A182 F316L | Chloride-bearing process fluids, marine air and pharmaceutical service |
| SS 321 blind flange | ASTM A182 F321 | High-temperature service between 425 and 815 °C |
| SS 347 blind flange | ASTM A182 F347 | Welded high-temperature piping in refineries and power plants |
| Duplex 2205 blind flange | ASTM A182 F51 / F60 | Strength with chloride resistance at a stainless-steel budget |
| Super Duplex 2507 blind flange | ASTM A182 F53 | Seawater and high-chloride service where strength also matters |
| Inconel 600 blind flange | ASTM B564 | High-temperature oxidation, caustic and nuclear service |
| Inconel 625 blind flange | ASTM B564 | Seawater, high strength and high temperature in one alloy |
| Inconel 718 blind flange | project / purchase specification dependent | Very high strength at temperatures up to about 650 °C |
| Incoloy 800 / 800H / 800HT blind flange | ASTM B564 | Furnaces, petrochemical heaters and high-temperature piping |
| Hastelloy C276 blind flange | ASTM B462 / B564 | The most aggressive mixed acids, wet chlorine and hypochlorite |
| Hastelloy C22 blind flange | ASTM B462 / B564 | Mixed oxidising and reducing acids, and weld overlays |
| Monel 400 blind flange | ASTM B564 | Seawater, hydrofluoric acid and marine service |
| Monel K500 blind flange | project / purchase specification dependent | High-strength pump shafts, bolting and springs in seawater |
| Super Duplex S32760 blind flange | ASTM A182 F55 | Seawater firewater, injection and offshore piping |
| ASTM A106 Gr B blind flange | ASTM A105 | High-temperature process and steam piping in refineries and power plants |
| ASTM A333 Gr 6 blind flange | ASTM A350 LF2 | Cold-climate and refrigerated piping down to −45 °C |
| ASTM A335 P11 blind flange | ASTM A182 F11 | Steam and hot-oil piping up to about 550 °C |
| ASTM A335 P22 blind flange | ASTM A182 F22 | High-pressure steam and hydrogen service up to about 580 °C |
Other flanges
Blind Flange dimensions — ASME B16.5 Class 150 & 300
Outside diameter, thickness and bolting are set by size and class. Values in mm; thickness excludes the 1.6 mm raised face.
| NPS | Cl 150 OD | Cl 150 thickness | Cl 150 bolt circle | Cl 150 bolts | Cl 300 OD | Cl 300 thickness | Cl 300 bolt circle | Cl 300 bolts |
|---|---|---|---|---|---|---|---|---|
| ½" | 90 | 9.6 | 60.3 | 4 × ½" | 95 | 12.7 | 66.7 | 4 × ½" |
| 1" | 110 | 12.7 | 79.4 | 4 × ½" | 125 | 15.9 | 88.9 | 4 × ⅝" |
| 1½" | 125 | 15.9 | 98.4 | 4 × ½" | 155 | 19.1 | 114.3 | 4 × ¾" |
| 2" | 150 | 17.5 | 120.7 | 4 × ⅝" | 165 | 20.7 | 127.0 | 8 × ⅝" |
| 3" | 190 | 22.3 | 152.4 | 4 × ⅝" | 210 | 27.0 | 168.3 | 8 × ¾" |
| 4" | 230 | 22.3 | 190.5 | 8 × ⅝" | 255 | 30.2 | 200.0 | 8 × ¾" |
| 6" | 280 | 23.9 | 241.3 | 8 × ¾" | 320 | 35.0 | 269.9 | 12 × ¾" |
| 8" | 345 | 27.0 | 298.5 | 8 × ¾" | 380 | 39.7 | 330.2 | 12 × ⅞" |
| 10" | 405 | 28.6 | 362.0 | 12 × ⅞" | 445 | 46.1 | 387.4 | 16 × 1" |
| 12" | 485 | 30.2 | 431.8 | 12 × ⅞" | 520 | 49.3 | 450.8 | 16 × 1⅛" |
Full chart: ASME B16.5 flange dimensions.
Blind flange — questions buyers ask
What is a blind flange?
A blind flange is a solid disc that closes the end of a pipe, valve or vessel nozzle. Use a blind flange to terminate a line, close a nozzle for future connection, or allow pressure testing. It takes the full line pressure plus bolting load, so it is often the heaviest flange in a class.
Can a blind flange be cut from plate?
For many sizes and classes, yes — especially in nickel alloys where forgings are expensive. The material then follows the plate standard and must be approved by the purchaser.
Which grades are blind flanges available in?
Inconel 825, SS 904L, SS 304, SS 304L, SS 310 / 310S, SS 316 / 316L, SS 321, SS 347, Duplex 2205, Super Duplex 2507, Inconel 600, Inconel 625, Inconel 718, Incoloy 800 / 800H / 800HT, Hastelloy C276, Hastelloy C22, Monel 400, Monel K500, Super Duplex S32760, ASTM A106 Gr B, ASTM A333 Gr 6, ASTM A335 P11, ASTM A335 P22.
Which standard covers blind flange dimensions?
ASME B16.5 · B16.47 · EN 1092-1. The material standard depends on the grade.
Sources: the ASTM / ASME specifications named on this page and producer datasheets · Last updated October 2026