FAQs about Self-Sealing Fasteners

When using just an O-Ring or deformable washer (regardless of material) as a pressure sealer you sacrifice the ability to fully clamp, plus the degree of thread sealing is not predictable. That's because the O-Ring or washer interferes with achieving 360° metal-to-metal contact between the underside of the head and mounting surface.

See Comparison Illustrations.

Both technologies share the goal of high-pressure sealing, but that's where the similarities end. The APM O-Ring washer design provides the user with a pre-assembled, one-piece fastener, ready to be installed in one step-eliminating the dependence of the installer to apply the correct amount of sealant/compound. Its inherent geometric chamber and nested O-Ring creates the perfect solution for maximum service reusability which is the result of a unique patented asymmetrical-shaped chamber.

Sealants and compounds do not allow for easy replacement. They usually require the screw or bolt to be drilled out for replacement which can be problematic. They are really intended for one-time use.

The APM design and patent (U.S. patent no. 3,175,454) was conceived to generate highpressure fastener sealing and maximum multiple usage. However, this frequently asked question cannot be answered with a simple number, because each application condition is different in terms of reinstallation frequency, in combination with environmental and operating conditions.

Because of the asymmetrical annular design, minimum O-Ring friction occurs producing minimum wear which results in maximum reusability. Repeat orders from many customers confirm satisfaction from field servicing using these fasteners.

Yes. A special silicone formulation is used that is resistant to salt water weather, dirt, dust, sunlight, ozone and most acids, prolonging frequency and life of these special self-sealing fasteners. They have a temperature range of -160° F to +500° F (-106° C to +260° C). The ring size is also special and are not commercial standard O-Ring sizes. This is important, because they have to be fabricated to conform to the special (patent no. 3,175,454) curvature configuration for the holding chamber to maintain minimum O-ring surface friction when torqued. (This is the essence of the patent approval which contributes to its reusability.)

The process requires that only 20% of the O-Ring surface be compressed and displaced into a defined clearance hole which completes the sealing action. By reducing movement and friction, the integrity of the O-Ring surface is protected from unnecessary wear which would otherwise expose the ring to degradation from contaminants that could reduce its future ability to seal at maximum torque levels.

Yes. We have a special bonding process which provides excellent paint adhesion.

Yes. For example, you can order an APM SEELSKREW®, SELBOLT® or SEELNUT® with a fully-adjustable, anti-vibration option. Choice of resilient engineered embedded polymer pellets, strips (bars), or standard/high-temperature, surface applied patches can be added to the threaded area for compression and locking action. Eliminates need for costly lock washers, cotter pins, or castellated nuts. Impervious to a wide range of chemicals, water and lubricants. Choice of materials.

Also available is a broad selection of bottled user-applied thread locking adhesives & sealants.

Standard nut configurations do not allow for effective O-Ring displacement the way conventional fasteners such as machine screws, bolts and rivets do. So, to meet the challenge, APM engineered a different technology that incorporates a permanently pressed molded silicone seal that forms a high-pressure seal along the threaded section and contact surface when torqued.

Fully adjustable and reusable, they resist vibration, provide metal-to-metal contact, and seal up to 20,000 psig (137,895kPa). under vacuum or high-pressure.