Ring gaskets are also known as RTJ gaskets or O-ring Gaskets. These gaskets are used for high-pressure services. They are solid rings of metal (cut from plate, pipe, or a forged ring) in different cross-sections such as the oval, round, and octagonal.

A special RTJ gasket comes with a hole in the center for pressure equalization in the subsea pipeline application. You can see the different types of RTJ gaskets in the image below.

rtj gaskets Types - Oval, RX, BX, Octagonal type

Ring Joint Gaskets are used with Ring Type Joint (RTJ) flanges. High surface stress is developed between an RTJ gasket and the flange groove when the RTJ gasket is bolted to a flange. This leads to the plastic deformation of this gasket.

Thus, the hardness of the gasket is kept less than the hardness of the flange groove. The only thing you have to take care of is that the hardness of the gasket shall always be less than flange material by at least 50 BHN. For more info, visit –Lamons

RTJ Gasket Materials and Hardness

A list of materials that can be used for metallic gaskets and the maximum acceptable hardness for these materials is given in ASME B16.20. Refer to the below table for more information.

GASKET MATERIALS BRINELL HARDNESS NUMBER (max) ROCKWELL HARDNESS NUMBER -B Scale (max) IDENTIFICATION
Soft iron 90 56 D
Low carbon steel 120 68 S
4-6% Chrome 1/2% molybdenum 130 72 F5
Type 410 Stainless Steel 170 86 S410
Type 304 Stainless Steel 160 83 S304
Type 316 Stainless Steel 160 83 S316
Type 347 Stainless Steel 160 83 S347
Type 410 Stainless Steel 170 86 S410

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RTJ Gasket Dimension Chart

Dimensions of RTJ Ring gaskets are covered in ASME B16.20. You can see the dimension chart below. Please check with the standard before using the chart.

During dimension inspection of the gasket, you should check for

  • Diameter – Inside / Outside
  • Width / Height
  • Thickness
  • Centering ring dimensions
  • Permissible Variations of Gasket dimensions are covered in ASME B16.20.
rtj gasket dimension inspection

Oval Ring Metal Gasket Dimensions

Oval Ring Gasket Dimensions
R no P-Pitch Dia A-Width B-Height Oval Ring
R-11 34.14 6.35 11.2
R-12 39.7 7.95 14.2
R-13 42.88 7.95 14.2
R-14 44.45 7.95 14.2
R-15 47.63 7.95 14.2
R-16 50.8 7.95 14.2
R-17 57.15 7.95 14.2
R-18 60.33 7.95 14.2
R-19 65.1 7.95 14.2
R-20 68.28 7.95 14.2
R-21 72.24 11.13 17.5
R-22 82.55 7.95 14.2
R-23 82.55 11.13 17.5
R-24 95.25 11.13 17.5
R-25 101.6 7.95 14.2
R-26 101.6 11.13 17.5
R-27 107.95 11.13 17.5
R-28 111.13 12.7 19.1
R-29 114.3 7.95 14.2
R-30 117.48 11.13 17.5
R-31 123.83 11.13 17.5
R-32 127 12.7 19.1
R-33 131.78 7.95 14.2
R-34 131.78 11.13 17.5
R-35 136.53 11.13 17.5
R-36 149.23 7.95 14.2
R-37 149.23 11.13 17.5
R-38 157.18 15.88 22.4
R-39 161.93 11.13 17.5
R-40 171.45 7.95 14.2
R-41 180.98 11.13 17.5
R-42 190.5 19.05 25.4
R-43 193.68 7.95 14.2
R-44 193.68 11.13 17.5
R-45 211.15 11.13 17.5
R-46 211.15 12.7 19.1
R-47 228.6 19.05 25.4
R-48 247.65 7.95 14.2
R-49 269.88 11.13 17.5
R-50 269.88 15.88 22.4
R-51 279.4 22.23 28.7
R-52 304.8 7.95 14.2
R-53 323.85 11.13 17.5
R-54 323.85 15.88 22.4
R-55 342.9 28.58 36.6
R-56 381 7.95 14.2
R-57 381 11.13 17.5
R-58 381 22.23 28.7
R-59 396.88 7.95 14.2
R-60 406.4 31.75 39.6
R-61 419.1 11.13 17.5
R-62 419.1 15.88 22.4
R-63 419.1 25.4 33.3
R-64 454.03 7.95 14.2
R-65 469.9 11.13 17.5
R-66 469.9 15.88 22.4
R-67 469.9 28.58 36.6
R-68 517.53 7.95 14.2
R-69 533.4 11.13 17.5
R-70 533.4 19.05 25.4
R-71 533.4 28.58 36.6
R-72 558.8 7.95 14.2
R-73 584.2 12.7 19.1
R-74 584.2 19.05 25.4
R-75 584.2 31.75 39.6
R-76 673.1 7.95 14.2
R-77 692.15 15.88 22.4
R-78 692.15 25.4 33.3
R-79 692.15 34.93 44.5
R-92 228.6 11.13 17.5

Octagonal Type Metal Gasket Dimensions

Octagonal Ring Gasket Dimensions
R no P-Pitch Dia A-Width H- Height Octagonal Ring C- Width of Flat on Octagonal Ring R1 – Radius Octagonal Ring
R-11 34.14 6.35 9.7 4.32 1.5
R-12 39.7 7.95 12.7 5.23 1.5
R-13 42.88 7.95 12.7 5.23 1.5
R-14 44.45 7.95 12.7 5.23 1.5
R-15 47.63 7.95 12.7 5.23 1.5
R-16 50.8 7.95 12.7 5.23 1.5
R-17 57.15 7.95 12.7 5.23 1.5
R-18 60.33 7.95 12.7 5.23 1.5
R-19 65.1 7.95 12.7 5.23 1.5
R-20 68.28 7.95 12.7 5.23 1.5
R-21 72.24 11.13 16 7.75 1.5
R-22 82.55 7.95 12.7 5.23 1.5
R-23 82.55 11.13 16 7.75 1.5
R-24 95.25 11.13 16 7.75 1.5
R-25 101.6 7.95 12.7 5.23 1.5
R-26 101.6 11.13 16 7.75 1.5
R-27 107.95 11.13 16 7.75 1.5
R-28 111.13 12.7 17.5 8.66 1.5
R-29 114.3 7.95 12.7 5.23 1.5
R-30 117.48 11.13 16 7.75 1.5
R-31 123.83 11.13 16 7.75 1.5
R-32 127 12.7 17.5 8.66 1.5
R-33 131.78 7.95 12.7 5.23 1.5
R-34 131.78 11.13 16 7.75 1.5
R-35 136.53 11.13 16 7.75 1.5
R-36 149.23 7.95 12.7 5.23 1.5
R-37 149.23 11.13 16 7.75 1.5
R-38 157.18 15.88 20.6 10.49 1.5
R-39 161.93 11.13 16 7.75 1.5
R-40 171.45 7.95 12.7 5.23 1.5
R-41 180.98 11.13 16 7.75 1.5
R-42 190.5 19.05 23.9 12.32 1.5
R-43 193.68 7.95 12.7 5.23 1.5
R-44 193.68 11.13 16 7.75 1.5
R-45 211.15 11.13 16 7.75 1.5
R-46 211.15 12.7 17.5 8.66 1.5
R-47 228.6 19.05 23.9 12.32 1.5
R-48 247.65 7.95 12.7 5.23 1.5
R-49 269.88 11.13 16 7.75 1.5
R-50 269.88 15.88 20.6 10.49 1.5
R-51 279.4 22.23 26.9 14.81 1.5
R-52 304.8 7.95 12.7 5.23 1.5
R-53 323.85 11.13 16 7.75 1.5
R-54 323.85 15.88 20.6 10.49 1.5
R-55 342.9 28.58 35.1 19.81 2.3
R-56 381 7.95 12.7 5.23 1.5
R-57 381 11.13 16 7.75 1.5
R-58 381 22.23 26.9 14.81 1.5
R-59 396.88 7.95 12.7 5.23 1.5
R-60 406.4 31.75 38.1 22.33 2.3
R-61 419.1 11.13 16 7.75 1.5
R-62 419.1 15.88 20.6 10.49 1.5
R-63 419.1 25.4 31.8 17.3 2.3
R-64 454.03 7.95 12.7 5.23 1.5
R-65 469.9 11.13 16 7.75 1.5
R-66 469.9 15.88 20.6 10.49 1.5
R-67 469.9 28.58 35.1 19.81 2.3
R-68 517.53 7.95 12.7 5.23 1.5
R-69 533.4 11.13 16 7.75 1.5
R-70 533.4 19.05 23.9 12.32 1.5
R-71 533.4 28.58 35.1 19.81 2.3
R-72 558.8 7.95 12.7 5.23 1.5
R-73 584.2 12.7 17.5 8.66 1.5
R-74 584.2 19.05 23.9 12.32 1.5
R-75 584.2 31.75 38.1 22.33 2.3
R-76 673.1 7.95 12.7 5.23 1.5
R-77 692.15 15.88 20.6 10.49 1.5
R-78 692.15 25.4 31.8 17.3 2.3
R-79 692.15 34.93 41.4 24.82 2.3
R-80 615.95 7.95 12.7 5.23 1.5
R-81 635 14.3 19.1 9.58 1.5
R-82 57.15 11.13 16 7.75 1.5
R-84 63.5 11.13 16 7.75 1.5
R-85 79.38 12.7 17.5 8.66 1.5
R-86 90.5 15.88 20.6 10.49 1.5
R-87 100.03 15.88 20.6 10.49 1.5
R-88 123.83 19.05 23.9 12.32 1.5
R-89 114.3 19.05 23.9 12.32 1.5
R-90 155.58 22.23 26.9 14.81 1.5
R-91 260.35 31.75 38.1 22.33 2.3
R-92 228.6 11.13 16 7.75 1.5
R-93 749.3 19.05 23.9 12.32 1.5
R-94 800.1 19.05 23.9 12.32 1.5
R-95 857.25 19.05 23.9 12.32 1.5
R-96 914.4 22.23 26.9 14.81 1.5
R-97 965.2 22.23 26.9 14.81 1.5
R-98 1022.35 22.23 26.9 14.81 1.5
R-99 234.95 11.13 16 7.75 1.5
R-100 749.3 28.58 35.1 19.81 2.3
R-101 800.1 31.75 38.1 22.33 2.3
R-102 857.25 31.75 38.1 22.33 2.3
R-103 914.4 31.75 38.1 22.33 2.3
R-104 965.2 34.93 41.4 24.82 2.3
R-105 1022.35 34.93 41.4 24.82 2.3

Tolerances in millimeters

  • Width of ring +/- 0.20 mm
  • Height of ring +1.3 mm to -0.5 mm
  • Width of end flat on octagonal ring +/- 0.20 mm
  • Average pith diameter of ring +/- 0.18 mm
  • Corner radius on octagonal ring +/- 0.50 mm
  • Angle +/- 1/2 degree
  • Angle +/- 1/2 degree

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Varun Patel - HardHat Engineer

About Author: Varun Patel is a Mechanical Engineer and an Oil & Gas Professional. He is a Certified Project Management Professional – PMP® from PMI® USA. With over nineteen years of experience, he has worked with Fortune 500 Oil & Gas Companies. Know more.