When just fastening is not enough
When the fastening system is under attack by hydraulic or pneumatic, internal or external pressure or when environmental contaminants are externally president and must be prevented from creeping past the fastener threads, selecting the right sealing method becomes paramount, there are many choices to explore ranging from liquid thread sealing adhesives, to tape, to elastomeric O-rings, to deformable washers or self-sealing fasteners with self-locking options.
The embedded O-ring technique offers a number of advantages over other sealing systems, such as simplicity, control, certainty and the ability to reuse infield servicing, delivered pre-assembled APM SEELSKEWS, SEELBLOTS and SEELRIVETS incorporated engineered O-ring typically silicon rubber, positioned in an asymmetrical groove that went to torqued, requires minimum compression accounting for less than twenty percent of its original size.
This relationship results in a pressure sealing rating up to 20,000 PSI and because a minimum O-ring movement within the channel and shank there’s minimum friction and wear so the O-ring will not easily degrade or tear, making multiple reinstallations possible. For optimum performance mounting hole should be slightly countersunk creating an ideal seating area pretty O-ring eliminating squeezing into the threaded area, proper seating also enables 360-degree metal to metal surface contact.
By contrast you to the deformable washer or simple O-ring will crush the sealing material to the point of preventing 360-degree metal to metal fastener contact, this makes it impossible to know what degree its sealing is achieved, if at all, and forget servicing reusability.
There’s the liquid thread sealing unlocking method alternative, unlike the embedded self-sealing method, some applications require a primer then sealant is applied, followed by curing which could take up to 24 hours.
Other issues include training the worker to know exactly how to apply the sealant or adhesive to the exact location and with a precise quantity, even field service and can be an issue the fastener is often rendered unusable as it may have to be either heated, sheared or drilled out for removal before replacement, other ancillary problems could be employee health and local disposal environmental requirements, none of these issues exists with APM’s embedded, one step O-ring design fasteners.
What about those fasteners that are subject to conditions of extreme vibration, vibration that goes beyond their ability to absorb? APM offers a number of time-proven, thread locking options, here the embedded polymer palette is positioned one to three threads back from the fasteners end and just below the depth at the thread. The pellet typically nylon, is compressed establishing locking, which takes place inside the threads, optimum vibration dampening is achieved locking the threads in place.
Another option is APM’s self-locking embedded polymer bar
APM’s self-locking embedded polymer bar, which operates similarly to the pallet. Like the pallet, no adhesive or thread distortion is required and it too, can operating a wide temperature range from minus 450 degrees Fahrenheit (-232 degrees Celsius) to plus 550 degrees Fahrenheit (287 degrees Celsius), depending on material selection. For those applications where is not desirable to mill or drill, to add a polymer insert, there’s the patch option, the APM patch dry coating process, fuses the patch material to the thread surface, the fasteners then ready for installation, without the need for curing or any special preparation. This process saves money by eliminating the need for costly hardware and is less expensive than buying bottled thread locking compounds. Patches are available for operating temperatures from minus 70 degrees Fahrenheit (-21 degrees Celsius) to plus 500 degrees Fahrenheit (260 degrees Celsius). Patches will not dry shrink or lose resiliency and are impervious to most chemicals.
APM embedded self-sealing fasteners incorporate an elastomeric O-ring in a groove which works exactly as it was originally intended when patented. But we employ a different system for self-healing nuts and washers, that’s because nut sealing presents a different challenge than screws bolts and rivets. Because the goal is to maintain and never compromise the fasteners original number of threads, our designers created a molded in elastomer seal, it contains threads on the inside diameter all the way up to the top of the nut. This provides one hundred percent gripping power as was originally intended, for securing to the bolt or stud threads. Using an O-ring in this application would mean fewer threads resulting in bulging and interfering with 360-degree metal to metal contact.
To make a washer that is both reusable, self-sealing and able to control pressure up to 100 PSI internal/external APM designed its seal-locks, self-sealing washer with a concave contoured, compressible, stainless steel disc. It’s bonded on one side with silicone rubber that extends from the inside the center hole to the outside diameter edge, for full sealing coverage, giving it an IP 66-68 ingress rating.
These washers are ideal for large through holes to 1 1/4 inches (31.75mm). Seal locks will seal slots, odd shaped holes, even round projected surfaces. The seal were no other washer can and UL recognized for NEMA Type 4X and Type 6 enclosure protection. They are also perfect for a variety of electro-mechanical, pneumatic and hydraulic applications such as systems employing celluloid valves. Universally accepted by industry and the military, third-party tested and recognized by UL, APM SEELSKREWS, SEELBOLTS, SEELRIVETS, SEELNUTS and SEELOC washers, solve sealing problems ordinary fasteners can’t.