O-Ring Groove Design Dovetail

O-Ring Dovetail Groove Design

Dovetail grooves are used to hold the O-ring in-place on a face seal groove during during assembly and maintenance of equipment. An undercut or dovetail groove has proven beneficial in many applications to keep the o-ring in place. This is an expensive groove to machine, however, and thus should be used only when absolutely necessary.

It should be noted that although this method has been used successfully, it is not generally recommended. The inherent characteristics of the groove design limit the amount of void area. Normally acceptable tolerance extremes, wide service temperature ranges and fluid media that cause high swell or the elastomer are conditions that cannot be tolerated in this type of groove design.

Standard Dovetail Groove Designs

Groove Design Dovetail StandardRadius "R" is critical.
Insufficient radius will potentially cause damage to the o-ring during installation, while excessive radius may contribute to extrusion.

O-Ring Size
AS568
W
Cross Section
L Squeeze % G R R1
Nominal Actual Gland Gland Width
004 to 050 1/16 .070
+/- .003
.050 to .052 27 .055 to .059 .005 1/64
102 to 178 3/32 .103
+/- .003
.081 to .083 21 .083 to .087 .010 1/64
201 to 284 1/8 .139
+/- .004
.111 to .113 20 .113 to .117 .010 1/32
309 to 395 3/16 .210
+/- .005
.171 to .173 18 .171 to .175 .015 1/32
425 to 475 1/4 .275
+/- .006
.231 to .234 16 .231 to .235 .015 1/16
Special 3/8 .375
+/- .007
.315 to .319 16 .315 to .319 .020 3/32

Metric Dovetail Groove Designs

Groove Design Dovetail MetricThe Surface Finish X, groove top and bottom:
For liquids X= 32 micro inches
For vacuum and gases X=16 micro inches.
For groove sides X=63 micro inches.

Radius "R" is critical.
Insufficient radius will potentially cause damage to the o-ring during installation, while excessive radius may contribute to extrusion.

W E F
Groove Width
R1 R2
Cross Section (mm) Groove Depth
E+/-0,05
F2 +/-0,05
(width to round corner)
F1 +/-0,05
(width to sharp corner)
Machining Radius Size Radius
3,0 2,40 2,45 2,60 0,4 0,25
3,5 - 3,53* 2,80 2,80 3,05 0,8 0,25
4,0 3,20 3,10 3,40 0,8 0,25
4,5 3,65 3,50 3,75 0,8 0,25
5,0 4,15 3,85 4,10 0,8 0,25
5,33* 4,40 4,10 4,35 0,8 0,25
5,5 4,6 4,20 4,60 0,8 0,4
5,7 4,8 4,35 4,75 0,8 0,4
6,0 5,05 4,55 4,95 0,8 0,4
6,5 5,50 4,90 5,30 0,8 0,4
6,99* - 7,0 5,95 5,25 5,65 1,5 0,4
7,5 6,40 5,60 6,00 1,5 0,4
8,0 6,85 6,00 6,50 1,5 0,5
8,4 7,25 6,25 6,80 1,5 0,5
8,5 7,35 6,35 6,90 1,5 0,5
9,0 7,80 6,70 7,25 1,5 0,5
9,5 8,20 7,05 7,60 1,5 0,5
10,0 8.70 7,40 7,95 1,5 0,5

* US/BS standard AS 568A