Features

• Positive Sealing–Pressure and Vacuum
• Cold-Formed for Superior Strength and Uniformity
• High Reusability
• Optional Self-Locking Capability

How They Work

Self-Seal® fasteners, manufactured exclusively by Long-Lok, are designed to provide the optimum combination of sealing and fastening in one complete unit. They are cold formed for strength and uniformity, and then assembled with O-rings capable of sealing almost any fluid or gas.

With Self-Seal fasteners, these resilient O-rings are positioned under the head in a precision-engineered groove, and are affected little by repeated assembly and disassembly. They provide a superior degree of sealing and re-usability to the common alternative techniques of chemical coatings or plastic washers that attempt to seal the thread form. And, unlike these common alternatives, with Self-Seal fasteners you’re not limited to a few compatible finishes or hampered by extra parts that need stocking, inventory and assembly.

Long-Lok offers a wide selection of materials, finishes and O-rings to configure an endless variety of Self-Seal Fasteners and custom components capable of withstanding operating temperatures from -75°F to +450°F (-59°C to +232°C).

Self-Seal® Method and Advantages

To understand why Long-Lok Self-Seal® fasteners are the most complete answer to combined fastening and sealing operations, it helps to know where the alternatives fall short.

Conventional Sealing Techniques
The two main alternatives are thread coatings (liquids or tapes), and external plastic washers.

• Coatings, such as Vibra-Seal® (which we also offer), are cost-effective for moderate performance applications -- especially for common fluid fittings where repeated disassembly is uncommon. But, since the coating is applied directly to the thread form, sealing properties deteriorate with reuse. Also, coatings are not compatible with all finishes.
• Plastic Washers also get their sealing properties through direct interaction with the thread form. Like thread coatings, they are prone to deterioration due to the cutting action of the threads they are trying to seal, thus limiting their reusability. Additionally, sealing washers, prone to cold flow, are separate components that must be assembled onto the fastener (typically with other washers), and calculated into the assembly dynamics and measurements; a consideration to factor into your actual installed cost.

Self-Seal® Sealing Technique
Self-Seal® Fasteners overcome all these limitations by placing an O-ring under the head for sealing. With this elegant solution, Self Seal fasteners offer these unique advantages:

• Assemble mating components using standard torque values.
• Specify any common surface finish.
• Metal-to-metal contact.
• High reusability.
• Positive sealing from either side of the assembly.

Self-Seal fasteners are designed and manufactured with a cold formed groove beneath the head of the fastener. As the fastener is tightened, the O-ring is compressed, squeezing the O-ring between the groove and mating surface to complete the seal. The design of the groove controls the amount of compression to the O-ring. And because O-rings retain their elastic memory, Self-Seal fasteners are reusable time after time.

Performance Tests

The performance tests described below were independently conducted by ITL Independent Testing Laboratories, Costa Mesa, California. Contact us for complete certified test results, available on all tests.

Pressure Failure Test
12 size 10-32 Self-Seal test specimens were installed into a test fixture and torqued to 23 inch-pounds. The assembly was then slowly pressurized until rupture or failure. Test specimens utilized silicone O-Rings. The average failure pressure over the 12 specimens was 24,136 PSIG.

Helium Mass-Spectrometer Leakage Test
Results: Using a Buna-N O-Ring there were no indications of helium leakage in excess of 5.0 x 10-5 SCC/Sec.

MIL-S-82496A Test
12 MS3212-43 Self-Seal specimens were subjected to the series of consecutive performance tests as specified in MIL-S-82496A.

Self-Seal O-Ring Materials

How to Specify

Self-Seal® fasteners are available in both standard and custom configurations.

Standard Configurations
Order standard configurations by part number. We show our part numbering system graphically on the download page (177 Kb Adobe Acrobat PDF file).

Custom Configurations
It doesn’t have to be exotic to be custom. Self-Seal “customs” may be:

• simply basic fastener types manufactured in a material or finish not offered as standard; or
• highly engineered, non-fastening, multi-piece components of your design, manufactured by Long-Lok.

Whichever of these descriptions fit your custom requirements, remember: If it needs to seal tight and seal right, each and every time, Self-Seal products are your best choice.

In addition to the materials and finishes listed in the ordering tables on the following page, Long-Lok can manufacture Self-Seal® fasteners and components using most other common materials and finishes; just let us know if you need something not listed.

Most common thread forms, including metric, can be supplied. For materials, finishes or thread forms not referenced, please contact us.

Here are items you should consider when specifying custom Self-Seal fasteners or components. Please review these, and then contact us with your application requirements.

Self-Locking Options for Self-Seal® Fasteners

When shock or vibration are present in your application, consider specifying Self-Seal fasteners manufactured with one of Long-Lok’s self-locking processes.



See for Yourself

Send us a sample of your part or fastener, along with a brief description of its application and performance requirements, and we’ll process it using the most appropriate Long-Lok thread locking or sealing method. Or, to sample a standard Long-Lok fastener, simply supply us with a part number. Samples are provided free of charge. Call your nearest Long-Lok facility for assistance.