Page 15: of Marine Technology Magazine (May/Jun 2026)

Design Approach

Referring to Figure 2: The radial seal design sequence is: 1. Using the Parker o-ring Radial seal design tables (ORD 5700, Section 4.2, Design Table 4-1), and Limits of Extrusion chart (See Figure 4), determine the maximum allowable gap.

Charts show either “diametral” or “radial,” so be aware when applying the numbers to “bore” (diametral) or “gap” (radial = ½ diametral). 2. Determine the minimum amount of material that can be removed from the ID of the tube to produce a circular bore.

Too much weakens the pressure case. 3. Subtract (2 x gap) dimension from the bore dimension.

This is the Plug OD. If using aluminum that will be anodized, adjust the dimensions to allow for surface growth (See “Anod- izing” below.)

Picking the gap: In designing the mating plug and bore, use

Image courtesy Parker Seal Company, adapted by author for this article the Parker spec for specifying the plug OD and the bore ID.

Figure 2 (Ref Parker ORD 5700, Design Table 4-1.).

There are some trade-offs: The Radial seal design sequence is shown: 1) determine

The larger the o-ring cross-section, the larger the allowable gap. gap, 2) determine tube ID, 3) with those two numbers,

The smaller the o-ring cross-section the less compressive calculate plug OD. www.marinetechnologynews.com 15

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