The present invention relates to a metallic seal for the containment of high pressure fluids, including gases, from cryogenic to highly elevated temperatures. More particularly, the present invention relates to pressure-energized, annular metallic lip seals with lateral offset, angular and axial misalignment capability.
In the field of fluid containment of high pressure fluids, resilient metallic seals are employed in applications where elastomeric and polymeric materials cannot be used because of extremely high pressures, high temperatures and/or aggressive media. Such sealing devices are produced in different configurations designed to meet a variety of operating requirements.
One such seal is the “Axial C-Seal”, a partial cross-section of which is shown in
Other seals have been developed to perform this function, for example, those shown in the following U.S. Pat. Nos.: 4,457,523; 4,854,600; 5,799,954; 6,257,594; and 6,446,978. All of these seals serve their purpose, but have limitations when required to be both pressure-energized and capable of accommodating significant misalignments of the cylindrical surfaces to be sealed.
In devices known as couplings, a rigid hollow proboscis or probe is inserted into a hollow receptacle in a fluid transmission system. The receptacle contains a sealing ring or multiple sealing rings, which are dilated by the inserted probe, thereby creating the required contact stresses to achieve fluid containment between the two bodies to be sealed together.
C-seals are presently employed in couplings. Occasionally, due to imperfect field installation practices, the probe will be forced into the receptacle before the centerlines or axes of the two components are properly aligned. When this occurs, the probe may dent one side of the c-seal, which may not be sufficiently resilient to elastically deform, and therefore may leave a gap on the opposite side which results in leakage of fluid when the joint is pressurized.
It is highly desirable to provide an improved metallic seal which overcomes the foregoing problems.
In accordance with the present invention it has now been found that a metallic seal has been provided which obtains the foregoing objectives.
The metallic seal of the present invention has a C-shaped portion which connects to a longitudinally extending portion. The c-shaped portion desirably has a discrete radius with a smaller radius than the axial c-seal, to prevent contact between the probe and this relatively rigid area during installation. The inside diameter of the c-shaped portion is desirably extended axially towards the end of the c-shaped portion and towards a first end of the seal, and slightly inwardly, desirably terminating in a small inwardly curled portion forming a lip. The opposed portion of the c-shaped portion connects to a longitudinally extending portion which extends above or beyond the c-shaped portion and which desirably terminates in a small outwardly curved portion. The overall configuration of the seal is somewhat L-shaped, or J-shaped.
Further features and advantages of the present invention will appear hereinbelow.
The present invention will be more readily understandable from a consideration of the accompanying drawings, wherein:
Referring now to the drawings in detail,
The preferred materials for the seals of the present invention include nickel super alloys and nickel cobalt alloys, although other metals may be used.
The seals of the present invention have several significant advantages. Thus the flexibility of the inward facing lip 29 is enhanced by increased distance from the more rigid c-shaped part of the section and it can be deflected radially by a lower force.
In addition, the configuration of the frustro-conical portion 44 may be reshaped by deflecting relatively easily to accommodate an off-center probe without plastic deformation of this region.
Still further, the seal of the present invention may be manufactured from a thicker material stock from that of the prior art axial-c-seal if desired without an appreciable increase in insertion force or galling tendencies.
In addition, greater material thickness and a close proximity between the installed probe and the deflected inner frustro-conical leg of the ring cross-section enables higher operating and proof pressures to be sustained without gross permanent deformation.
Also, the seals of the present invention have enhanced reliability. Multiple insertions of the probe into the seals have been a problem for prior art seals.
A further advantage of the seals of the present invention is a tapered cross-section of the frustro-conical portion. This even more flexible feature is advantageous for dynamic, sliding applications, albeit at slow speeds because of reduction of contact stresses.
Naturally, variations in the seal are contemplated. For example, the longitudinally extending portion could be conical or have a slight curve. The c-shaped portion could have variations and flats and need not be uniform. All shapes could be slightly irregular.
Various coatings, including silver or gold, may be beneficially applied to the seal or its contact surfaces in order to improve its sealing efficiency. For dynamic applications special anti-galling, low-friction coatings may be applied. Thus, sealing contact areas may be coated with soft, lubricious and/or anti-galling materials.
It is to be understood that the invention is not limited to the illustrations described and shown herein, which are deemed to be merely illustrative of the best modes of carrying out the invention, and which are susceptible of modification of form, size, arrangement of parts and details of operation. The invention rather is intended to encompass all such modifications which are within its spirit and scope as defined by the claims.