ASME B16.20 Type R Ring Gasket

ASME B16.20 Type R ring gaskets are basic octagonal or oval ring-type joint (RTJ) gaskets used with API 6B and ASME B16.5/B16.47 RTJ flanges. They are manufactured according to a specific profile and hardness to ensure metal-to-metal sealing under high pressure.

Types: Oval or Octagonal 
Materials: Soft iron, carbon and low alloy steels, stainless steels, and other CRAs
Standards: API 6A, ASME B16.20

ASME B16.20 Type R ring gasket is a metal RTJ gasket designed to create a high-integrity, metal-to-metal seal in RTJ flanges.
It is compressed into the groove of an RTJ flange, where the gasket undergoes controlled deformation, forming a tight and leak-proof seal even under extreme conditions.

The Type R gasket is the original and most common RTJ design, used extensively across industries that require reliable sealing in critical operations.

Types of ASME B16.20 Type r Ring Gaskets

Oval Ring Gasket

  • Traditional oval-shaped cross section.
  • Provides a reliable metal-to-metal seal.
  • Fits only oval-shaped RTJ grooves.
  • Used in older installations or where oval grooves are specified.

 Octagonal Ring Gasket

  • Most commonly used Type R gasket.
  • Octagonal cross section improves sealing efficiency.
  • Fits modern standard RTJ grooves (both octagonal and some oval-compatible grooves).
  • Provides better pressure resistance and tighter sealing than oval type.
Type R Ring Gasket Dimensions and Tolerances

ASME B16.20 Type r Ring Gaskets Dimensions

Ring Number Average Pitch Diameter of Ring, P Width of Ring, A Height of Ring, Oval B Height of Ring, Octagonal H Height of Ring, C Height of Ring, R1
R-11 34.14(1.344) 6.35(0.250) 11.2(0.44) 9.7(0.38) 4.32(0.170) 1.5(0.06)
R-12 39.70(1.563) 7.95(0.313) 14.2(0.56) 12.7(0.50) 5.23(0.206) 1.5(0.06)
R-13 42.88(1.688) 7.95(0.313) 14.2(0.56) 12.7(0.50) 5.23(0.206) 1.5(0.06)
R-14 44.45(1.750) 7.95(0.313) 14.2(0.56) 12.7(0.50) 5.23(0.206) 1.5(0.06)
R-15 47.63(1.875) 7.95(0.313) 14.2(0.56) 12.7(0.50) 5.23(0.206) 1.5(0.06)
R-16 50.80 (2.000) 7.95(0.313) 14.2(0.56) 12.7(0.50) 5.23(0.206) 1.5(0.06)
R-17 57.15(2.250) 7.95(0.313) 14.2(0.56) 12.7(0.50) 5.23(0.206) 1.5(0.06)
R-18 60.33(2.375) 7.95(0.313) 14.2(0.56) 12.7(0.50) 5.23(0.206) 1.5(0.06)
R-19 65.10(2.563) 7.95(0.313) 14.2(0.56) 12.7(0.50) 5.23(0.206) 1.5(0.06)
R-20 68.28(2.688) 7.95(0.313) 14.2(0.56) 12.7(0.50) 5.23(0.206) 1.5(0.06)
R-21 72.24(2.844) 11.13(0.438) 17.5(0.69) 16.0(0.63) 7.75(0.305) 1.5(0.06)
R-22 82.55(3.250) 7.95(0.313) 14.2(0.56) 12.7(0.50) 5.23(0.206) 1.5(0.06)
R-23 82.55(3.250) 11.13(0.438) 17.5(0.69) 16.0(0.63) 7.75(0.305) 1.5(0.06)
R-24 95.25(3.750) 11.13(0.438) 17.5(0.69) 16.0(0.63) 7.75(0.305) 1.5(0.06)
R-25 101.60(4.000) 7.95(0.313) 14.2(0.56) 12.7(0.50) 5.23(0.206) 1.5(0.06)
R-26 101.60(4.000) 11.13(0.438) 17.5(0.69) 16.0 (0.63) 7.75(0.305) 1.5(0.06)
R-27 107.95(4.250) 11.13(0.438) 17.5(0.69) 16.0(0.63) 7.75(0.305) 1.5(0.06)
R-28 111.13(4.375) 12.70(0.500) 19.1(0.75) 17.5(0.69) 8.66(0.341) 1.5(0.06)
R-29 114.30(4.500) 7.95(0.313) 14.2(0.56) 12.7(0.50) 5.23(0.206) 1.5(0.06)
R-30 117.48(4.625) 11.13(0.438) 17.5(0.69) 16.0(0.63) 7.75(0.305) 1.5(0.06)
R-31 123.83(4.875) 11.13(0.438) 17.5(0.69) 16.0(0.63) 7.75(0.305) 1.5(0.06)
R-32 127.00 (5.000) 12.70(0.500) 19.1(0.75) 17.5(0.69) 8.66(0.341) 1.5(0.06)
R-33 131.78(5.188) 7.95(0.313) 14.2(0.56) 12.7(0.50) 5.23(0.206) 1.5(0.06)
R-34 131.78(5.188) 11.13(0.438) 17.5(0.69) 16.0 (0.63) 7.75(0.305) 1.5(0.06)
R-35 136.53(5.375) 11.13(0.438) 17.5(0.69) 16.0(0.63) 7.75(0.305) 1.5(0.06)
R-36 149.23(5.875) 7.95(0.313) 14.2(0.56) 12.7(0.50) 5.23(0.206) 1.5(0.06)
R-37 149.23(5.875) 11.13(0.438) 17.5(0.69) 16.0(0.63) 7.75(0.305) 1.5(0.06)
R-38 157.18(6.188) 15.88(0.625) 22.4(0.88) 20.6(0.81) 10.49(0.413) 1.5(0.06)
R-39 161.93(6.375) 11.13(0.438) 17.5(0.69) 16.0(0.63) 7.75(0.305) 1.5(0.06)
R-40 171.45(6.750) 7.95(0.313) 14.2(0.56) 12.7(0.50) 5.23(0.206) 1.5(0.06)
R-41 180.98(7.125) 11.13(0.438) 17.5(0.69) 16.0(0.63) 7.75(0.305) 1.5(0.06)
R-42 190.50(7.500) 19.05(0.750) 25.4 (1.00) 23.9(0.94) 12.32(0.485) 1.5(0.06)
R-43 193.68(7.625) 7.95(0.313) 14.2(0.56) 12.7(0.50) 5.23(0.206) 1.5(0.06)
R-44 193.68(7.625) 11.13(0.438) 17.5(0.69) 16.0(0.63) 7.75(0.305) 1.5(0.06)
R-45 211.15(8.313) 11.13(0.438) 17.5(0.69) 16.0(0.63) 7.75(0.305) 1.5(0.06)
R-46 211.15(8.313) 12.70(0.500) 19.1(0.75) 17.5(0.69) 8.66(0.341) 1.5(0.06)
R-47 228.60(9.000) 19.05(0.750) 25.4(1.00) 23.9(0.94) 12.32(0.485) 1.5(0.06)
R-48 247.65(9.750) 7.95(0.313) 14.2(0.56) 12.7(0.50) 5.23(0.206) 1.5(0.06)
R-49 269.88(10.625) 11.13(0.438) 17.5(0.69) 16.0(0.63) 7.75(0.305) 1.5(0.06)
R-50 269.88(10.625) 15.88(0.625) 22.4(0.88) 20.6(0.81) 10.49(0.413) 1.5(0.06)
R-51 279.40(11.000) 22.23(0.875) 28.7(1.13) 26.9(1.06) 14.81(0.583) 1.5(0.06)
R-52 304.80(12.000) 7.95(0.313) 14.2(0.56) 12.7(0.50) 5.23(0.206) 1.5(0.06)
R-53 323.85(12.750) 11.13(0.438) 17.5(0.69) 16.0(0.63) 7.75(0.305) 1.5(0.06)
R-54 323.85(12.750) 15.88(0.625) 22.4(0.88) 20.6(0.81) 10.49(0.413) 1.5(0.06)
R-55 342.90(13.500) 28.58(1.125) 36.6(1.44) 35.1(1.38) 19.81(0.780) 2.3(0.09)
R-56 381.00(15.000) 7.95(0.313) 14.2(0.56) 12.7(0.50) 5.23(0.206) 1.5(0.06)
R-57 381.00(15.000) 11.13(0.438) 17.5(0.69) 16.0(0.63) 7.75(0.305) 1.5(0.06)
R-58 381.00(15.000) 22.23(0.875) 28.7(1.13) 26.9(1.06) 14.81(0.583) 1.5(0.06)
R-59 396.88(15.625) 7.95(0.313) 14.2(0.56) 12.7(0.50) 5.23(0.206) 1.5(0.06)
R-60 406.40(16.000) 31.75(1.250) 39.6(1.56) 38.1(1.50) 22.33(0.879) 2.3(0.09)
R-61 419.10(16.500) 11.13(0.438) 17.5(0.69) 16.0(0.63) 7.75(0.305) 1.5(0.06)
R-62 419.10(16.500) 15.88(0.625) 22.4(0.88) 20.6(0.81) 10.49(0.413) 1.5(0.06)
R-63 419.10(16.500) 25.40(1.000) 33.3(1.31) 31.8(1.25) 17.30(0.681) 2.3(0.09)
R-64 454.03(17.875) 7.95(0.313) 14.2(0.56) 12.7(0.50) 5.23(0.206) 1.5(0.06)
R-65 469.90(18.500) 11.13(0.438) 17.5(0.69) 16.0(0.63) 7.75(0.305) 1.5(0.06)
R-66 469.90(18.500) 15.88(0.625) 22.4(0.88) 20.6(0.81) 10.49(0.413) 1.5(0.06)
R-67 469.90(18.500) 28.58(1.125) 36.6(1.44) 35.1(1.38) 19.81(0.780) 2.3(0.09)
R-68 517.53 (20.375) 7.95(0.313) 14.2(0.56) 12.7(0.50) 5.23(0.206) 1.5(0.06)
R-69 533.40(21.000) 11.13(0.438) 17.5(0.69) 16.0(0.63) 7.75(0.305) 1.5(0.06)
R-70 533.40(21.000) 19.05(0.750) 25.4 (1.00) 23.9(0.94) 12.32(0.485) 1.5(0.06)
R-71 533.40(21.000) 28.58(1.125) 36.6(1.44) 35.1(1.38) 19.81(0.780) 2.3(0.09)
R-72 558.80(22.000) 7.95(0.313) 14.2(0.56) 12.7(0.50) 5.23(0.206) 1.5(0.06)
R-73 584.20(23.000) 12.70(0.500) 19.1(0.75) 17.5(0.69) 8.66(0.341) 1.5(0.06)
R-74 584.20(23.000) 19.05(0.750) 25.4(1.00) 23.9(0.94) 12.32(0.485) 1.5(0.06)
R-75 584.20(23.000) 31.75(1.250) 39.6(1.56) 38.1(1.50) 22.33(0.879) 2.3(0.09)
R-76 673.10(26.500) 7.95(0.313) 14.2(0.56) 12.7(0.50) 5.23(0.206) 1.5(0.06)
R-77 692.15(27.250) 15.88(0.625) 22.4(0.88) 20.6(0.81) 10.49(0.413) 1.5(0.06)
R-78 692.15(27.250) 25.40(1.000) 33.3(1.31) 31.8(1.25) 17.30(0.681) 2.3(0.09)
R-79 692.15(27.250) 34.93(1.375) 44.5(1.75) 41.4(1.63) 24.82(0.977) 2.3(0.09)
R-80 615.95(24.250) 7.95(0.313) 12.7(0.50) 5.23(0.206) 1.5(0.06)
R-81 635.00 (25.000) 14.30(0.563) 19.1(0.75) 9.58(0.377) 1.5(0.06)
R-82 57.15(2.250) 11.13(0.438) 16.0(0.63) 7.75(0.305) 1.5(0.06)
R-84 63.50(2.500) 11.13(0.438) 16.0(0.63) 7.75(0.305) 1.5(0.06)
R-85 79.38(3.125) 12.70(0.500) 17.5(0.69) 8.66(0.341) 1.5(0.06)
R-86 90.50(3.563) 15.88(0.625) 20.6(0.81) 10.49(0.413) 1.5(0.06)
R-87 100.03(3.938) 15.88(0.625) 20.6(0.81) 10.49(0.413) 1.5(0.06)
R-88 123.83(4.875) 19.05(0.750) 23.9(0.94) 12.32(0.485) 1.5(0.06)
R-89 114.30(4.500) 19.05(0.750) 23.9(0.94) 12.32(0.485) 1.5(0.06)
R-90 155.58(6.125) 22.23(0.875) 26.9(1.06) 14.81(0.583) 1.5(0.06)
R-91 260.35(10.250) 31.75(1.250) 38.1(1.50) 22.33(0.879) 2.3(0.09)
R-92 228.60(9.000) 11.13(0.438) 17.5(0.69) 16.0(0.63) 7.75(0.305) 1.5(0.06)
R-93 749.30(29.500) 19.05(0.750) 23.9(0.94) 12.32(0.485) 1.5(0.06)
R-94 800.10(31.500) 19.05(0.750) 23.9(0.94) 12.32(0.485) 1.5(0.06)
R-95 857.25(33.750) 19.05(0.750) 23.9(0.94) 12.32(0.485) 1.5(0.06)
R-96 914.40(36.000) 22.23(0.875) 26.9(1.06) 14.81(0.583) 1.5(0.06)
R-97 965.20(38.000) 22.23(0.875) 26.9(1.06) 14.81(0.583) 1.5(0.06)
R-98 1022.35(40.250) 22.23(0.875) 26.9(1.06) 14.81(0.583) 1.5(0.06)
R-99 234.95(9.250) 11.13(0.438) 16.0(0.63) 7.75(0.305) 1.5(0.06)
R-100 749.30(29.500) 28.58(1.125) 35.1(1.38) 19.81(0.780) 2.3(0.09)
R-101 800.10(31.500) 31.75(1.250) 38.1(1.50) 22.33(0.879) 2.3(0.09)
R-102 857.25(33.750) 31.75(1.250) 38.1(1.50) 22.33(0.879) 2.3(0.09)
R-103 914.40(36.000) 31.75(1.250) 38.1(1.50) 22.33(0.879) 2.3(0.09)
R-104 965.20(38.000) 34.93(1.375) 41.4(1.63) 24.82(0.977) 2.3(0.09)
R-105 1022.35(40.250) 34.93(1.375) 41.4(1.63) 24.82(0.977) 2.3(0.09)

GENERAL NOTE: Tolerances:

  • 23 deg = angle, ±0 deg 30 min (±1 /2 deg)
  • A = width of ring, ±0.20 mm (±0.008 in.)
  • B, H = height of ring, +1.3 mm, −0.5 mm (+0.05 in., −0.02 in.)
  • Variation in height throughout the entire circumference of any given ring shall not exceed 0.5 mm (0.02 in.) within these tolerances.
  • C = width of flat on octagonal ring, ±0.20 mm (±0.008 in.)
  • P = average pitch diameter of ring, ±0.18 mm (±0.007 in.)
  • R1 = radius in ring, ±0.5 mm (±0.02 in.)
Ring Number ASME B16.5 150 ASME B16.5 300-600 ASME B16.5 900 ASME B16.5 1500 ASME B16.5 2500 API 6B 720-960 [Note(1)] API 6B 2000 API 6B 3000 API 6B 5000 ASME B16.47 Series A 150 ASME B16.47 Series A 300-600 ASME B16.47 Series A 900
R-11 1/2
R-12 [Note (2)] 1/2
R-13 3/4 1/2
R-14 [Note (2)] 3/4
R-15 1
R-16 1 1 1 3/4 1 1 1 1
R-17 1 1/4
R-18 1 1/4 [Note (2)] 1 1/4 1 14 1 1/4 1 1/4 1 1/4
R-19 1 1/2
R-20 112 [Note(2)] 1 1/2 1 1/2 1 1/2 1 1/2 1 1/2
R-21 114
R-22 2
R-23 2 1 1/2 2 2
R-24 [Note (2)] 2 2 2
R-25 2 1/2
R-26 212 2 2 1/2 2 1/2
R-27 [Note (2)] 2 1/2 2 1/2 2 1/2
R-28 2 1/2
R-29 3
R-30 [Note (3)] 3
R-31 3 3 3 3 3
R-32 3
R-33 3 1/2
R-34 3 1/2
R-35 3 3
R-36 4
R-37 4 4 4 4 4 3 1/2
R-38 4
R-39 4 4
R-40 5
R-41 5 5 5 5 5
R-42 5
R-43 6
R-44 5 5
R-45 6 6 6 6 6
R-46 6 6
R-47 6
R-48 8
R-49 8 8 8 8 8
R-50 8 8
R-51 8
R-52 10
R-53 10 10 10 10 10
R-54 10 10
R-55 10
R-56 12
R-57 12 12 12 12 12
R-58 12
R-59 14
R-60 12
R-61 14 14 14 14
R-62 14
R-63 14
R-64 16
R-65 16 16 16
R-66 16 16
R-67 16
R-68 18
R-69 18 18 18
R-70 18 18
R-71 18
R-72 20
R-73 20 20 20
R-74 20 20
R-75 20
R-76 24
R-77 24
R-78 24
R-79 24
R-80 22
R-81 22
R-82 1
R-84 1 1/2
R-85 2
R-86 2 1/2
R-87 3
R-88 4
R-89 35
R-90 5
R-91 10
R-92
R-93 26
R-94 28
R-95 30
R-96 32
R-97 34
R-98 36
R-99 8 8
R-100 26
R-101 28
R-102 30
R-103 32
R-104 34
R-105 36

GENERAL NOTE: End flanges to API 6D and API 600 use gaskets for equivalent pipe size under ASME B16.5 or ASME B16.47 Series A.

NOTES:

  1. Class 720, 960, and 10000 flanges to API 6B are obsolete. Data are for information only.
  2. There are no Class 900 flanges in NPS 1 ∕ 2 through NPS 21 ∕ 2 (use Class 1500).
  3. R-30 is for lapped joint only.

Materials Used for ASME B16.20 Type r 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

  • Oil & Gas: Wellhead equipment, manifolds, valves, API 6A systems

  • Refinery & Petrochemical: High-temperature steam, high-pressure reactors

  • Marine & Offshore: Subsea equipment, FPSO systems, corrosive media

  • Power Generation: Boilers, heat exchangers, turbines

  • High-Pressure Piping: Class 600–2500 flange connections

Refinery & Petrochemical

Markings & Identification

Each gasket includes clear markings according to ASME B16.20:

  • Gasket Number (e.g., R-21)
  • Profile (Octagonal / Oval)
  • Material Code (e.g., S316, INC625)
  • Heat Number
  • Manufacturer Mark: MILLSFORGE
  • Standard: ASME B16.20

Example marking:
R-45 OCT S316 ASME B16.20 HEAT 2548 MILLSFORGE

r ring gasket

Why Choose MillsForge for ASME B16.20 Type r Ring Gaskets?

MillsForge provides high-quality ASME B16.20 Type R Ring Gaskets, manufactured in compliance with ASME standards and supported by ISO 9001:2005 quality management. Whether you need octagonal or oval profiles, and regardless of material—carbon steel, stainless steel, or advanced corrosion-resistant alloys—MillsForge can meet your high-pressure, high-temperature, refinery, and offshore application requirements.

What We Offer

  • Fully compliant ASME B16.20 Type R ring gaskets
  • Octagonal and oval profile options
  • Wide material selection for high-pressure and corrosive environments
  • Precision machining with strict dimensional and surface-finish control
  • Fast delivery and global supply capability

MillsForge ensures that every Type R ring gasket meets the highest industry standards for sealing reliability, durability, and safety.

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