PRINTER FRIENDLY VERSION

Static Seals.

After considering the factors that generally affect all O-ring seals, you must also think about your specific type of application. O-ring seals fall into two main application categories: static and dynamic. Static seals exist where there is no relative motion between the mating surfaces being sealed. Both static and dynamic seals engender their own unique concerns. Relatively-speaking, however, static seals are easier to design because they can handle wider tolerances, rougher surface finishes, and higher pressure limits. There are four major types of static seals:

STATIC RADIAL SEALS
Static radial seals are formed when squeeze (compression) is applied to the inside diameter (I.D.) and outside diameter (O.D.) of the O-ring. Cap and plug type configurations commonly utilize radial seals. An example of a static radial O-ring seal for a male gland is shown in Figure 93. A static radial O-ring seal for a female gland is shown in Figure 94. Gland design measurements for static radial O-ring seals can be found in Table 41. Gland dimensions can be found in Table 42.

STATIC AXIAL (FACE) SEALS
Static axial seals (also known as face seals) are formed when squeeze is applied to the top and bottom surfaces of the O-ring. Axial seals are most often used in face (flange) type designs where an O-ring seats against the groove’s low-pressure side. A static axial O-ring seal (internal pressure) is shown in Figure 95. A static axial O-ring seal (external pressure) is shown in Figure 96. Gland design measurements for static axial O-ring seals can be found in Table 43. Gland dimensions can be found in Table 44.

STATIC SEALS WITH “DOVETAIL” GROOVES
Dovetails are face type designs that have been customized to form static seals by structurally immobilizing the O-ring within the gland. Dovetails are more expensive and difficult to design and install than the other types of static seals. A dovetail seal is shown in Figure 97. Gland design measurements for dovetail grooves can be found in Table 45.

STATIC CRUSH SEALS
Static crush seals use a male cover with a machined 45° angle to “crush” an O-ring into the corner of a triangular gland. Because the resulting distortion to the O-ring is permanent, it cannot be reused later. An example of a static crush seal is shown in Figure 98. Gland design measurements for crush seals can be found in Table 46.

STRAIGHT THREAD TUBE FITTING SEALS
Another static seal application is the straight thread tube fitting seal. We will not go into the subject in detail here because this particular type is not as common a configuration as the above mentioned seals. Boss dimensions for industrial straight thread tube fitting seals can be found in Table 47.

The gland dimensions for the above seals (with the exception of the tube fitting seal) can be calculated with our online O-Ring Calculator.

“Static seals exist where there is no relative motion between the mating surfaces being sealed.”

 


Figures 93-94


Table 41


Table 42


Figures 95-96


Table 43


Table 44


Figure 97


Table 45


Figure 98


Table 46


Table 47