ASME B16.20 Type BX Ring Gasket
ASME B16.20 Type BX ring gaskets are pressure-energized ring-type joint (RTJ) gaskets designed for use with API 6A Type BX RTJ flanges. They provide a metal-to-metal sealing solution specifically developed for very high-pressure applications and are designed to withstand pressures up to 20,000 psi, depending on size and specification.
Types: BX (pressure-energized, high-pressure RTJ profile)
Materials: Soft iron, carbon steel, low alloy steels, stainless steels, and corrosion-resistant alloys (CRAs)
Standards: API 6A, ASME B16.20
The ASME B16.20 Type BX ring gasket is a precision-machined metal gasket engineered to deliver a fully confined, pressure-energized seal in BX-type RTJ flanges. The BX gasket is designed with a pressure-relief hole and a robust geometry that ensures a high-integrity seal under extreme pressure conditions. Once installed in the BX groove, the gasket is compressed, and internal pressure further enhances sealing performance.
Type BX gaskets are widely used in ultra-high-pressure systems, including oil & gas wellhead equipment, Christmas trees, subsea systems, high-pressure manifolds, petrochemical units, and other applications where maximum sealing integrity and reliability are required.
Types of ASME B16.20 Type BX Ring Gaskets
They are available in the following variations:
Standard BX Rings (BX-150 to BX-303)
- The most common BX type.
- Designed exclusively for API 6A Type BX RTJ flanges.
- Suitable for very high-pressure systems up to 20,000 psi.
- Used in wellheads, Christmas trees, manifolds, high-pressure valves, and critical oil & gas equipment.
BX Rings with Pressure-Relief Hole
- BX gaskets always include a pressure-relief hole (a mandatory feature in Type BX design).
- The hole prevents pressure lock during installation and operation.
- Ensures safe depressurization and avoids trapped cavity pressure.
- Required for all BX applications due to extreme pressure conditions.
ASME B16.20 Type BX Ring Gaskets Dimensions
ASME B16.20 Type BX ring gaskets are pressure-energized RTJ (Ring Type Joint) gaskets designed for API 6A Type BX flanges. They look similar to Type RX but are engineered for much higher pressure service, providing a fully confined, pressure-energized seal capable of handling pressures up to 20,000 psi, depending on size.
| Ring Number | Nominal Size,mm (in.) | Outside Diameter of Ring, 0.D.,mm (in.) | Height of Ring, H,mm(in.) | Width of Ring, A,mm(in.) | Outside Diameter of Flat, 0.D.T.,mm (in.) | Width of Flat, C,mm (in.) | Hole Size,D,mm (in.) [Note(1)] |
|---|---|---|---|---|---|---|---|
| BX-150 | 43(1 11/16) | 72.19(2.842) | 9.30(0.366) | 9.30(0.366) | 70.87(2.790) | 7.98(0.314) | 1.5(0.06) |
| BX-151 | 46(1 13/16) | 76.40(3.008) | 9.63(0.379) | 9.63(0.379) | 75.03(2.954) | 8.26(0.325) | 1.5(0.06) |
| BX-152 | 52(2 1/16) | 84.68(3.334) | 10.24(0.403) | 10.24(0.403) | 83.24(3.277) | 8.79(0.346) | 1.5(0.06) |
| BX-153 | 65(2 9/16) | 100.94(3.974) | 11.38(0.448) | 11.38(0.448) | 99.31(3.910) | 9.78(0.385) | 1.5(0.06) |
| BX-154 | 78(3 1/16) | 116.84(4.600) | 12.40(0.488) | 12.40(0.488) | 115.09(4.531) | 10.64(0.419) | 1.5(0.06) |
| BX-155 | 103(4 1/16) | 147.96(5.825) | 14.22(0.560) | 14.22(0.560) | 145.95(5.746) | 12.22(0.481) | 1.5(0.06) |
| BX-156 | 179(7 1/16) | 237.92(9.367) | 18.62(0.733) | 18.62(0.733) | 235.28(9.263) | 15.98(0.629) | 3.0(0.12) |
| BX-157 | 229(9) | 294.46(11.593) | 20.98(0.826) | 20.98(0.826) | 291.49(11.476) | 18.01(0.709) | 3.0(0.12) |
| BX-158 | 279(11) | 352.04(13.860) | 23.14(0.911) | 23.14(0.911) | 348.77(13.731) | 19.86(0.782) | 3.0(0.12) |
| BX-159 | 346(13 5/8) | 426.72(16.800) | 25.70(1.012) | 25.70(1.012) | 423.09(16.657) | 22.07(0.869) | 3.0(0.12) |
| BX-160 | 346(13 5/8) | 402.59(15.850) | 23.83(0.938) | 13.74(0.541) | 399.21(15.717) | 10.36(0.408) | 3.0(0.12) |
| BX-161 | 422(16 5/8) | 491.41(19.347) | 28.07(1.105) | 16.21(0.638) | 487.45(19.191) | 12.24(0.482) | 3.0(0.12) |
| BX-162 | 422(16 5/8) | 475.49(18.720) | 14.22(0.560) | 14.22(0.560) | 473.48(18.641) | 12.22(0.481) | 1.5(0.06) |
| BX-163 | 476(18 3/4) | 556.16(21.896) | 30.10(1.185) | 17.37(0.684) | 551.89(21.728) | 13.11(0.516) | 3.0(0.12) |
| BX-164 | 476(18 3/4) | 570.56(22.463) | 30.10(1.185) | 24.59(0.968) | 566.29(22.295) | 20.32(0.800) | 3.0(0.12) |
| BX-165 | 540(21 1/4) | 624.71 (24.595) | 32.03(1.261) | 18.49(0.728) | 620.19(24.417) | 13.97(0.550) | 3.0(0.12) |
| BX-166 | 540(21 1/4) | 640.03(25.198) | 32.03(1.261) | 26.14(1.029) | 635.51(25.020) | 21.62(0.851) | 3.0(0.12) |
| BX-167 | 680(26 3/4) | 759.36(29.896) | 35.86(1.412) | 13.11(0.516) | 754.28(29.696) | 8.03(0.316) | 1.5(0.06) |
| BX-168 | 680(26 3/4) | 765.25(30.128) | 35.86(1.412) | 16.05(0.632) | 760.17(29.928) | 10.97(0.432) | 1.5(0.06) |
| BX-169 | 130(5 1/8) | 173.51(6.831) | 15.85(0.624) | 12.93(0.509) | 171.27(6.743) | 10.69(0.421) | 1.5(0.06) |
| BX-170 | 168(6 5/8) | 218.03(8.584) | 14.22(0.560) | 14.22(0.560) | 216.03(8.505) | 12.22(0.481) | 1.5(0.06) |
| BX-171 | 218(8 9/16) | 267.44(10.529) | 14.22(0.560) | 14.22(0.560) | 265.43(10.450) | 12.22(0.481) | 1.5(0.06) |
| BX-172 | 283(11 5/32) | 333.07(13.113) | 14.22(0.560) | 14.22(0.560) | 331.06(13.034) | 12.22(0.481) | 1.5(0.06) |
| BX-303 | 762(30) | 852.75(33.573) | 37.95(1.494) | 16.97(0.668) | 847.37(33.361) | 11.61(0.457) | 1.5(0.06) |
GENERAL NOTES:
(a) Radius, R, shall be 8% to 12% of the gasket height, H.
(b) Tolerances:
- 23 deg = angle, ±0 deg 15 min (±1 ∕ 4 deg)
- A = width of ring, +0.20 mm, −0.00 mm (+0.008 in., −0 in.) Variation in width throughout the entire circumference of any ring shall not exceed 0.10 mm (0.004 in.) within these tolerances.
- C = width of flat, +0.15 mm, −0.00 mm (+0.006 in., −0 in.)
- D = hole size, ±0.5 mm (±0.02 in.)
- H = height of ring, +0.20 mm, −0.00 mm (+0.008 in., −0 in.) Variation in height throughout the entire circumference of any ring shall not exceed 0.10 mm (0.004 in.) within these tolerances.
- O.D. = outside diameter of ring, +0.00 mm, −0.15 mm (+0 in., −0.005 in.)
- O.D.T. = outside diameter of flat, ±0.05 mm (±0.002 in.)
- R = radius of ring [see General Note (a)]
NOTE: (1) One pressure passage hole is required per gasket as illustrated. The centerline of the hole shall be located at the midpoint of dimension C.
Pipe Size, NPS, by API 6BX Pressure Class
| Ring Number | 2000 | 3000 | 5000 | 10000 | 15000 | 20000 |
|---|---|---|---|---|---|---|
| BX-150 | 1 11/16 | 1 11/16 | ||||
| BX-151 | 1 13/16 | 1 13/16 | 1 13/16 | |||
| BX-152 | 2 1/16 | 2 1/16 | 2 1/16 | |||
| BX-153 | 2 9/16 | 2 9/16 | 2 9/16 | |||
| BX-154 | 3 1/16 | 3 1/16 | 3 1/16 | |||
| BX-155 | 4 1/6 | 4 1/6 | 4 1/6 | |||
| BX-156 | 7 1/16 | 7 1/16 | 7 1/16 | |||
| BX-157 | 9 | 9 | 9 | |||
| BX-158 | 11 | 11 | 11 | |||
| BX-159 | 13 5/8 | 13 5/8 | 13 5/8 | |||
| BX-160 | 13 5/8 | |||||
| BX-161 | 16 3/4 | |||||
| BX-162 | 16 3/4 | 16 3/4 | 16 3/4 | |||
| BX-163 | 18 3/4 | |||||
| BX-164 | 18 3/4 | 18 3/4 | ||||
| BX-165 | 21 1/4 | |||||
| BX-166 | 21 1/4 | |||||
| BX-167 | 26 3/4 | |||||
| BX-168 | 26 3/4 | |||||
| BX-169 | 5 1/8 | |||||
| BX-170 | 6 5/8 | 6 5/8 | ||||
| BX-171 | 8 9/16 | 8 9/16 | ||||
| BX-172 | 11 5/32 | 11 5/32 | ||||
| BX-303 | 30 | 30 |
NOTES:
- Class 720, 960, and 2900 flanges to API 6B are obsolete. Data are for information only.
- Crossover flange connection.
Materials Used for ASME B16.20 Type BX Ring Gaskets
- Soft Iron
- Carbon Steel & Low Alloy Steels
- Stainless Steel
In the oil and gas, chemical, and seawater system industries, CRA (Corrosion-Resistant Alloy) refers to special metallic materials with high corrosion resistance, such as:
- Inconel series (e.g., 625, 718)
- Incoloy series (e.g., 825, 925)
- Monel 400
- Hastelloy series (e.g., C276, C22)
- Duplex / Super Duplex (e.g., 2205, 2507)
- 904L
- Alloy 20
- Titanium alloys
| Material | Identification | DIN | B.S. | ASTM / UNS | Hardness Max (HB) | Hardness Max (HRB) | Min Temp (C) | Max Temp (C) | Density (g/cm3) |
|---|---|---|---|---|---|---|---|---|---|
| Soft Iron | D | 90 | 56 | -60 | 500 | 7.85 | |||
| Low Carbon Steel | S | 120 | 68 | -40 | 500 | 7.85 | |||
| ASTM A182 F5 | F5 | 1.7362 | F5 | 130 | 72 | -40 | 650 | 7.9 | |
| SS304 | S304 | 1.4301 | 304S15/16 | S30400 | 160 | 83 | -250 | 550 | 7.9 |
| SS304L | S304L | 1.4306 | 304S11 | S30403 | 160 | 83 | -250 | 550 | 7.9 |
| SS309 | S309 | 1.4828 | 309S24 | S30900 | 160 | 83 | -250 | 1000 | 7.9 |
| SS316 | S316 | 1.4401 | 316S16 | S31600 | 160 | 83 | -100 | 1000 | 7.9 |
| SS316L | S316L | 1.4404 | 316S11/13 | S31603 | 160 | 83 | -100 | 550 | 7.9 |
| SS316Ti | S316Ti | 1.4571 | 320S31 | S31635 | 160 | 83 | -100 | 550 | 7.8 |
| SS321 | S321 | 1.4541 | 321S12/49/87 | S32100 | 160 | 83 | -250 | 850 | 7.9 |
| SS347 | S347 | 1.455 | 347S31 | S34700 | 160 | 83 | -250 | 850 | 7.9 |
| SS410 | S410 | 1.4006 | 410S21 | S41000 | 170 | 86 | -20 | 650 | 7.8 |
| 254 SMO | 6Mo | 1.4547 | S31254 | 180 | 89 | -100 | 550 | 8 | |
| 904L | S904L | 1.4539 | SUS890L | N08904 | 180 | 89 | -250 | 400 | 8 |
| Duplex F51 | F51 | 1.4462 | 31853 | S31803 / S32205 | 230 | 99 | -40 | 300 | 7.8 |
| Super Duplex F53 | F53 | 1.441 | S32750 | 230 | 99 | -40 | 300 | 7.8 | |
| Super Duplex F55 | F55 | 1.4501 | S32760 | 250 | 102 | -40 | 300 | 7.8 | |
| Brass (CuZn37) | CuZn37 | 2.0321 | CZ108 | C27200 | 60 | -100 | 350 | 8.5 | |
| Nickel 200 | Ni200 | 2.4066 | NA11 | N02200 | 110 | 62 | -250 | 600 | 8.9 |
| Monel 400 | MONEL400 | 2.436 | NA13 | N04400 | 160 | 83 | -250 | 600 | 8.8 |
| Inconel 600 | INC600 | 2.4816 | NA14 | N06600 | 160 | 83 | -100 | 950 | 8.4 |
| Inconel 625 | INC625 | 2.4856 | NA21 | N06625 | 210 | 95 | -50 | 650 | 8.44 |
| Inconel 718 | INC718 | N07718 | 160 | 83 | -125 | 700 | 8.24 | ||
| Incoloy 800 | INC800 | 1.4876 | NA15 | N08800 | 160 | 83 | -100 | 850 | 8 |
| Incoloy 825 | INC825 | 2.4858 | NA16 | N08825 | 195 | 92 | -100 | 450 | 8.14 |
| Hastelloy B2 | HB2 | 2.4617 | N10665 | 230 | 99 | -200 | 450 | 9.2 | |
| Hastelloy C276 | HC276 | 2.4819 | N10276 | 210 | 95 | -200 | 400 | 8.9 | |
| Titanium Grade 2 | Ti2 | 3.7035 | TA2 | R50400 | 215 | 96 | -250 | 350 | 4.5 |
Application
ASME B16.20 Type BX ring gaskets are pressure-energized RTJ gaskets designed for extremely high-pressure, high-temperature, and critical sealing environments. They are used exclusively with API 6A Type BX flanges and are suitable for ultra-high-pressure operations where maximum leak integrity is essential.
- Oil & Gas Wellhead Equipment
- High-Pressure Christmas Trees & Manifolds
- High-Pressure Valves & Connectors
- Drilling, Completion & Production Systems
- Subsea & Offshore High-Pressure Installations
- Ultra-High-Pressure Pipelines & Flowlines
Markings & Identification
Standard markings typically include:
- Gasket Type – e.g., BX
- Ring Number / Size – e.g., BX-155
- Material Grade – e.g., CS, SS316, Inconel 625, Duplex, etc.
- Manufacturer’s Name or Trademark
- Heat / Batch Number – ensures full traceability
- Standard Reference – ASME B16.20
- Hardness (when required)
Example marking:
BX-155 • SS316 • ASME B16.20 • Heat No. 12345 • MillsForge
Why Choose MillsForge for ASME B16.20 Type BX Ring Gaskets?
MillsForge provides high-performance ASME B16.20 Type BX Ring Gaskets, engineered for ultra-high-pressure RTJ flange applications up to API 6A / ASME Class 20,000 psi. Manufactured under ISO 9001:2005 quality control, our BX gaskets feature a pressure-energized sealing structure that ensures superior metal-to-metal tightness under extreme internal pressures.
What We Offer
- Fully compliant ASME B16.20 / Type BX ring gaskets
- Pressure-energized sealing design for ultra-high-pressure systems
- Wide selection of materials suitable for sour-service, H₂S, and offshore corrosion environments
- Precision machining with controlled hardness and strict dimensional tolerances
- Fast delivery and worldwide supply capability
MillsForge ensures every Type BX ring gasket meets the toughest industry requirements for sealing performance, reliability, and operational safety.
