GASKET ASSEMBLY FOR SEALING MATING SURFACES

Developed at NASA Marshall Space Flight Center (MSFC), these low-cost technologies use a thermal element to seal, bond, braze, and/or weld static joints. Joints fabricated with these technologies can be permanently assembled with minimal process variability, may optionally be disassembled for service, and do not degrade over time. NASA seeks to transfer the Thermal Seal technology to private industry for use in commercial applications.

Benefits

Low cost
Welding or brazing control problems eliminated
No volatile organic compounds produced
Machining eliminated
Compatible with existing gasket-cutting systems
Thinner joints for reduced relaxation problems
Easy to use
Fast melting and curing process
Low ignition risk

Potential Commercial Uses

These technologies could be used in a wide variety of static sealing applications for bolted, bonded, brazed, and welded joints:

Chemical/industrial piping joints
Marine engine and transmission housing joints
Piping joints for heating, ventilation, and air conditioning (HVAC) steam, chilled water, and refrigerant
Automotive engine cooling system housing joints
Sealed electrical housings and cabinet joints

The Technology

Surface irregularities, joint pressure extrusion, and stress relaxation can cause leaks in conventionally bolted and gasketed joints. Although liquid sealants can reduce leaks by filling surface imperfections, adhering to joint surfaces, and minimizing gasket thickness, process control is difficult, curing is time consuming, fumes introduce an environmental concern, and servicing can be difficult. Liquid sealants used in a highly finished joint can fail, resulting from sealant breakdown or extrusion. Brazed and welded joints eliminate some limitations and costs of bolted joints, but they increase undesirable process variability and hinder future disassembly. To address the limitations of these conventional joining and sealing technologies, NASA Marshall Space Flight Center developed new thermal joint techniques. For a typical installation, an electrically or thermally conductive substrate assembly is positioned in the joint under a preload and uniformly heated. An electrically conductive substrate is heated by passing an electrical current, either continuous or impulse, through it. A thermally conductive substrate is heated by connecting the substrate to an external heat source. Once the substrate is heated, some preload is released into the interface to complete the connection. The joint is fully cured within a few minutes after the heat source is disconnected from the substrate. Substrates are generally coated with adhesives, thermoplastics, or braze alloys that melt when heated. For flanged and bolted joints, a flat substrate is coated on both sides with an adhesive, a thermoplastic, or a braze alloy. For sleeve joints, the conductive substrate is in the form of a hollow cylinder coated on the inside. For welded joints, an uncoated conductive element might be fabricated from a perforated or mesh material to enhance joining.

Patent Number

Contact for Licensing Information

If your company is interested in commercializing the Gasket Assembly for Sealing Mating Surfaces or if you need additional information, please reference case no. MFS-31175 and contact:

Technology Transfer Department
Patent Licensing Information
Mail Code CD30
Marshall Space Flight Center, AL 35812
Email:benita.hayes@msfc.nasa.gov