Understanding AS568 139 Groove Planning
The 139 seal size is common in small machines, valves, gauges, and compact housings. It uses a nominal 3/32 inch cross section. The free inside diameter is about 2.175 inches. Those values are only the start. A working groove also needs squeeze, stretch, width, fill, and tolerance checks. It also helps buyers compare stock seals, compound choices, backup rings, and drawing notes before any purchase order is issued during tooling review meetings.
Why Groove Depth Matters
Groove depth controls squeeze. Squeeze is the amount the round section is compressed after assembly. Too little squeeze may leak at low pressure. Too much squeeze can raise friction, damage edges, and shorten life. Static radial seals often use more squeeze than moving seals. Face seals usually need enough axial squeeze to stay tight after pressure cycling.
Why Width And Fill Matter
The groove cannot be sized from depth alone. The ring must have room to deform. It may also swell in service. Fill compares the ring section area with the groove section area. A very full groove can trap rubber and create high stress. A very loose groove may let the ring roll, twist, or extrude.
Using The Calculator
This calculator begins with AS568 139 dimensions, then lets you adjust every important design item. You can change the seal style, squeeze target, installation stretch, width factor, tolerances, temperature growth, and material swell. The tool returns groove depth, groove width, estimated diameters, squeeze range, and gland fill range.
Design Notes
Use the result as a planning aid, not as final authority. Real hardware needs surface finish checks, pressure limits, extrusion gap review, material compatibility, and assembly testing. Sharp edges should be broken. Lead in chamfers should protect the seal. When a drawing is released, compare these values with the gland recommendations from the seal maker and the project standard.
Practical Review
Check the worst case values before cutting metal. Use maximum cross section with minimum groove space for fill. Use minimum cross section with maximum depth for low squeeze. Review both ends of the range. If either limit fails, change the groove, choose another seal size, or reduce the assembly gap. Document the selected assumptions with every exported report.