Boss, Face, and Flange O-Rings Overview

Used commonly in hydraulic settings, Boss o-rings, O-Ring Face Seals, and Flange o-rings are relied on to provide an efficient, secure seal in high-pressure applications. All three types have their own specific set of sizes related to their associated fittings. These o-ring sizes can be bought in kits or individual sizes. Click any of the following o-ring types to jump to their respective sections.

Boss O-Rings                                          O-Ring Face Seals                                           Flange O-Rings

Boss O-Rings

900 Series Boss o-rings are used in sealing straight thread tube Boss fittings (ORB) associated with hydraulic equipment. Boss o-rings are recommended by the National Fire Protection Association (NFPA) for medium and high-pressure hydraulic systems. Boss o-ring sizes fall under the AS568 900 Series classification. Nitrile 90 Durometer o-rings are typically used, however, a multitude of o-ring compounds come in Boss sizes.

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Boss O-Ring Size Chart

Boss o-ring sizes and corresponding dimensions are shown in the interactive table below. The first column references the Tube Outside Diameter associated with the o-ring measurements. Dash Numbers in the second column link to their specific size filtering in our online store.

Tube OD AS568 Dash # CS Inch ID Inch
3/32 901 0.056 0.185
1/8 902 0.064 0.239
3/16 903 0.064 0.301
1/4 904 0.072 0.351
5/16 905 0.072 0.414
3/8 906 0.078 0.468
7/16 907 0.082 0.53
1/2 908 0.087 0.644
9/16 909 0.097 0.706
5/8 910 0.097 0.755
11/16 911 0.116 0.863
3/4 912 0.116 0.924
13/16 913 0.116 0.986
7/8 914 0.116 1.047
1 916 0.116 1.171
1-1/8 918 0.116 1.355
1-1/4 920 0.118 1.475
1-1/2 924 0.118 1.72
1-3/4 928 0.118 2.09
2 932 0.118 2.337

O-Ring Face Seals (ORFS)

SAE O-Ring Face Seal (ORFS) fittings are also used to seal hydraulic systems. These o-rings sit within the face of the fitting to create a seal between two connected metal surfaces. When the connection is tightened, the o-ring compresses against a flat face of the mating fitting or tube. O-Ring Face Seal sizes fall under the AS568 Zero Series classification. Though Nitrile 90 Durometer o-rings are mostly used, there are many o-ring compounds that are available in Face sizes.

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O-Ring Face Seal (ORFS) Size Chart

O-Ring Face Seal sizes and corresponding dimensions are shown in the interactive table below. The first column references the ORS Tube Size associated with the o-ring measurements. Dash Numbers in the second column link to their specific size filtering in our online store.

ORS Tube Size AS568 Dash # CS Nominal ID Nominal OD Nominal CS Inch ID Inch
-4 011 1/16 5/16 7/16 0.07 0.301
-6 012 1/16 3/8 1/2 0.07 0.364
-8 014 1/16 1/2 5/8 0.07 0.489
-10 016 1/16 5/8 3/4 0.07 0.614
-12 018 1/16 3/4 7/8 0.07 0.739
-16 021 1/16 15/16 1-1/16 0.07 0.926
-20 025 1/16 1-3/16 1-5/16 0.07 1.176
-24 029 1/16 1-1/2 1-5/8 0.07 1.489

Flange O-Rings

SAE 4-Bolt Flange o-rings seal high-pressure fluid systems such as pipes, pumps, and valves. Flange connector assemblies are flat metal surfaces that are bolted together (with an o-ring gasket) to form a sealed connection. Flange connections can also be disassembled for easy access to modify the system, clean, or inspect it. Flange o-ring sizes are contained within the AS568 200 Series classification. Nitrile 90 Durometer o-rings are mostly utilized, though multiple o-ring compounds are available in Flange sizes.

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If you require more information on Boss o-rings, O-Ring Face Seals, or Flange o-rings, please give us a call at 832-448-5550 or fill out the Product Inquiry Form to receive a quote or more information.

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Flange O-Ring Size Chart

Flange o-ring sizes and corresponding dimensions are shown in the interactive table below. Nitrile 90 Durometer Flange o-rings are Code 61 (up to 3,000 PSI) and Code 62 (up to 6,000 PSI), the standard and high-pressure classes. The first column references the flange size in inches. Dash Numbers in the second column link to their specific size filtering in our online store.

SAE Flange Size AS568 Dash # Tubing Dash Size CS Nominal ID Nominal OD Nominal CS Inch ID Inch
1/2 210 -8 1/8 3/4 1 0.139 0.734
5/8 212 -10 1/8 7/8 1-1/8 0.139 0.859
3/4 214 -12 1/8 1 1-1/4 0.139 0.984
1 219 -16 1/8 1-5/16 1-9/16 0.139 1.296
1-1/4 222 -20 1/8 1-1/2 1-3/4 0.139 1.484
1-1/2 225 -24 1/8 1-7/8 2-1/8 0.139 1.859
2 228 -32 1/8 2-1/4 2-1/2 0.139 2.234
2-1/2 232 -40 1/8 2-3/4 3 0.139 2.734
3 237 -48 1/8 3-3/8 3-5/8 0.139 3.359
3-1/2 241 -56 1/8 3-7/8 4-1/8 0.139 3.859
4 245 -64 1/8 4-3/8 4-5/8 0.139 4.359
5 253 -80 1/8 5-3/8 5-5/8 0.139 5.359