Abstract:
The present invention discloses a pressured O-ring type sealing system which allows for effective seals without expensive and time consuming machining of the sealing surface. The O-ring sealing system of the present invention allows the sealing member to conform to the natural surface irregularities of the sealing surface and to compensate for any eccentricities between the plug and the inner diameter of the member being sealed.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to seals, to methods of sealing, and to apparatus having such seals. In another aspect, the present invention relates to O-ring seals, to methods of sealing, and to apparatus having such seals. In even another aspect, the present invention relates to pressurized O-ring seals, to methods of sealing, and to apparatus having such seals. In still another aspect, the present invention relates to pressurized expandable O-ring seals, to methods of sealing, and to apparatus having such seals. 
     2. Description of the Related Art 
     O-ring type seals are commonly used to form an effective seal between two mating parts. An example of an O-ring type seal includes a plug having a gland groove in which a O-type seal is placed. In order for such a plug to seal a tubular member, the O-ring must have a diameter larger than the both the inner diameter of tubular member and the outer diameter of the plug. When the plug is inserted into the tubular member, the O-ring is squeezed between the two thereby forming a seal. Typically, for such a seal to be effective, the inner diameter of the tubular member must be machined smoothed at the point of sealing. 
     In another example, a plug can include screw threads. The tubular member would include complimentary threads and would also normally include lead-in angles to allow an O-ring to be squeezed down when entering the sealing area of the tubular member as the plug is screwed in. To form an effective seal, the tubular member will again require machining to remove any scale or other surface roughness at the sealing area, and provide an even surface for the O-ring to seat against. A disadvantage of this type of O-ring seal is that the threaded area on the tubular member must be under-cut to avoid damage to the O-ring by the threads on the tubular member as the plug is being inserted. 
     In order to make an effective seal, it is therefore common practice in the prior art to have the O-ring gland groove slightly larger than the inner diameter of the O-ring and wider than the cross section of the O-ring. This design gives the squeeze to the O-ring and allows axial movement of the O-ring as it is inserted into the sealing area. A typical O-ring has a ‘squeeze’ or reduction in its original cross section of about 10% to about 15% to form a seal. 
     Therefore, there is a need in the art for an O-ring seal that does not suffer from the disadvantages of the prior art, to a method of making such a seal, and to apparatus including such a seal. 
     Therefore, there is a need in the art for an O-ring seal that conforms to any sealing surface, to a method of making such a seal, and to apparatus including such a seal. 
     There is even another need in the art for an effective O-ring seal that does require expensive time consuming machining of and/or undercuts to the sealing surface, to a method of making such a seal, and to apparatus including such a seal. 
     These and other needs in the art will become apparent to those of skill in the art upon review of this specification, including its drawings and claims. 
     SUMMARY OF THE INVENTION 
     It is an object of the present invention to provide for an O-ring seal that does not suffer from the disadvantages of the prior art. 
     It is another object of the present invention to provide for an effective O-ring seal that conforms to any sealing surface. 
     It is even another object of the present invention to provide for an effective O-ring seal that does require expensive time consuming machining of and/or undercuts to the sealing surface. 
     These and other objects of the present invention will become apparent to those of skill in the art upon review of this specification, including its drawings and claims. 
     According to one embodiment of the present invention, there is provided a sealing apparatus, which first includes a plug having a groove. Positioned in the groove is seal, generally an O-ring type seal, defining a liquid reservoir within the groove. A passage with a valve is provided to the liquid reservoir, for providing pressure to a liquid within the reservoir. 
     According to another embodiment of the present invention, there is provided a sealing apparatus, which in addition to the above, further includes a mating member defining an orifice for receiving the plug such that the seal abuts against a wall of the orifice. 
     According to even another embodiment of the present invention, there is provided a sealing apparatus, which in addition to the above, further includes threads on the plug, and a threaded mating member defining an orifice for receiving the plug, such that the plug abuts against a wall of the orifice, with the threads of the plug engaged with the threads of the mating member. 
     According to still another embodiment of the present invention, there is provided a method of sealing an orifice, with the method including placement of a plug as described above in the orifice, such that the seal is positioned to seal the orifice. The method further includes application of pressure to the fluid to expand the seal, thereby forming a pressurized seal. 
     These and other embodiments of the present invention will become apparent to those of skill in the art upon review of this specification, including its drawings and claims. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIGS. 1A and 1B are cross sectional views of one prior art O-ring seal showing a tubular member A, and a plug B having groove D in which O-ring C is placed, showing respectively, plug B in an unsealed and sealed position. 
     FIGS. 2A and 2B are cross-sectional views of another prior art O-ring seal showing plug B having screw threads G and tubular member A having receiving threads F. 
     FIG. 3, is a cross-sectional view of a prior art O-ring illustrating gland groove D as being slightly larger than the inner diameter of O-ring C and wider than the cross section of the O-ring. 
     FIG. 4A, is a cross-sectional view of sealing system  10  of the present invention shown generally to include plug member  12 , groove  14  suitable for receiving sealing member  16 , and check valve  22  connected to channel  18 . 
     FIG. 4B, is a cross-sectional view of sealing system  10  of the present invention inserted into outer member  24 . 
     FIG. 5 is an illustration showing that the width of groove  14  of sealing system  10  is smaller than the outer diameter  34  of the cross-section of sealing member  16 . 
     FIG. 6 is an illustration showing the cross-sectional area of sealing member  16  could optionally contain an open area  17 . 
     FIG. 7, is an illustration of the operation of sealing system  10  of the present invention showing fluid  26  being forced through channel  18  and into groove  14  causing sealing member  16  to seal against outer member  24 . 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Before discussing the present invention, reference will first be made to the prior art, namely FIGS. 1A,  1 B,  2 A,  2 B and  3 . 
     FIGS. 1A and 1B are a cross sectional view of one illustration of a prior art O-ring type seal showing a tubular member A being sealed with a plug B having gland groove D in which O-ring C is placed. In order for plug B to seal tubular member B, O-ring C must have a diameter larger than the both the inner diameter of tubular C and the outer diameter of plug B such that when plug B is inserted into tubular member A, O-ring C is squeezed between the two thereby forming a seal which will require the inner diameter of tubular member A to be machined smoothed. 
     FIGS. 2A and 2B are a cross-sectional view of another illustration of a prior art O-ring seal. In this prior art example, plug B includes screw threads G and tubular member A includes receiving threads F. As shown in FIG. 2B of the prior art seal, tubular member A normally includes lead-in angles E to allow O-ring C to be squeezed down when entering the sealing area H as plug B is screwed into tubular member A. For an effective seal, tubular member A in FIG. 2B will require machining to remove any scale or other surface roughness at sealing area H to provide an even surface for O-ring C. Another disadvantage of the prior art O-ring seal of FIGS. 2A is that the threaded area on tubular member A must under-cut to avoid damage to O-ring C by threads F as plug B is inserted into tubular member A. 
     In order to make an effective seal, it is therefore common practice in the prior art, as illustrated in FIG. 3, to have the O-ring gland groove D slightly larger than the inner diameter of O-ring C and wider than the cross section of the O-ring. This gives the squeeze to the O-ring and allows axial movement of the O-ring as it is inserted into the sealing area. For an effective seal of the type shown the prior art O-ring C must typically have a ‘squeeze’ or reduction in its original cross section of about 10% to about 15%. 
     Referring now to FIGS. 4A-7, there is shown one embodiment of the sealing system  10  of the present invention. Referring to FIG. 4A, sealing system  10  is shown generally to include plug member  12  having groove  14  suitable for receiving sealing member  16 . Plug member  12  includes check valve  22  connected to channel  18  which is in fluid communication with groove  14 . Referring to FIG. 4B, sealing system  10  is designed to be inserted directly into and form a seal with outer member  24 . 
     Referring still to FIGS. 4A and 4B, plug member  12  may be of any shape suitable to insert into outer member  24 . Preferably, outer member  24  is a tubular member having an inner diameter with plug member  12  having a slightly smaller outer diameter such that plug member  12  may be inserted into and removed from tubular member  24 . 
     Plug member  12  may be made of any suitable material. Non-limiting examples of suitable materials include plastic, metal, metal alloy or steel. Preferably, plug member  12  is steel. 
     Groove  14  is a continuous groove surrounding plug  16 . Groove  14  may be of any suitable shape to receive sealing member  16 . Generally, the width of groove  14  must be less than the outer diameter  34 . Preferably, referring now to FIG. 5, the width of grove  14  must be in the range of about 5% to about 30% less than cross-section  34  of sealing member  16 . More preferably, the width of groove  14  must be in the range of about 10% to about 20% less than the cross section  34  of sealing member  16 . 
     While sealing member  16  is shown in the figures to have a roughly circular cross-sectional area, it is understood that sealing member  16  may have any suitable cross-sectional shape to form a seal between the outer diameter of the plug and the inner diameter of the tubular member. Non-limiting examples of suitable cross-section shapes of sealing member  16  include circular, semi-circular or oblong. Optionally, as shown in FIG. 6, the cross-sectional area of sealing member  16  could contain an open area  17 . 
     The sealing member  16  may be made of any material suitable to form a seal between the outer diameter of the plug an the inner diameter of the tubular member. Preferably, for high temperature and chemical resistance, sealing member  16  is made of a cross-linked or vulcanized elastomer such as disclosed in U.S. Pat. No. 5,254,616 incorporated herein by reference. Examples of suitable elastomers include nitrile butadiene rubber, nitrile silicon rubber, neoprene, vinyldine fluoride, and urethane. More preferably, sealing member  16  is made of nitrile butadiene rubber, a commercially available example of which is BUNA N available from Moss Seal Company or Apple Rubber Products, Inc. 
     Channel  18  cuts through plug  12  and connects check valve  22  to groove  14 . Channel  18  may be of any suitable size and shape to provide a path for fluid  26  introduced through valve  22  to flow into groove  14  and put pressure on sealing member  16 . 
     Check valve  22  may be any device, as is known in the art, to allow fluid to be introduced into channel  18  to apply and hold pressure on sealing member  16  such that sealing member  16  forms a seal against outer member  24 . Preferably, check valve  22  is a leak proof grease fitting. 
     Referring now to FIG. 7, in operation plug  12  is inserted into outer member  24 . A grease gun  36  or other delivery means for fluid  26  is attached to check valve  22 . Fluid  26  is forced through channel  18  and into groove  14 . Fluid  26  applies pressure to sealing member  16  thereby forcing it up against the inner diameter of outer member  24  creating a seal. 
     Fluid  26  may be any suitable fluid to provide enough pressure to expand sealing member  16  against outer member  24 . Non-limiting examples of suitable fluids include hydraulic fluid, paraffinic and cycloparaffinic petroleum fractions, greases, oils, glycols, hydrocarbons or combinations thereof, as well as air or other gases. Preferable, fluid  26  is a liquid hydrocarbon of suitable viscosity such that when depressurized, plug  12  may be easily removed from outer member  24 . More preferably, fluid  26  may be a commercially available oil treatment products such as is sold under the tradename STP. 
     EXAMPLES 
     The following examples are provided merely to illustrate the present invention, and are not intended to limit the scope of the claims. 
     Example 1 
     PURPOSE: The purpose of this example is to test the sealing ability of the expandable O-ring system on the Slickwall gun system. 
     TEST SETUP: A 1 foot section of gun tube was cut from the parent joint of 4″ line pipe. Four each 0.75″ diameter holes at 90° to each other were machined in the ends of the tube section. The subs were designed to easily slide into the tube section with the O-ring OD the same size of the sub&#39;s OD, thus allowing the O-ring to pass the 4 machined holes without being cut. No surface preparation was done to the ID of the tube section. The O-ring groove was connected to a thru hole to an external grease fitting. This allowed for pressurizing up on the O-ring groove to expand the O-ring making the O-ring conform to the ID of the tube section. With both subs inserted into the tube section and the O-rings expanded, the assembly was placed into a Navy gun and pressurized to 4000 psi and held for 5 minutes. 
     RESULTS The pressure chamber was depressurized and the gun section removed. The grease fitting was removed to depressurize the O-ring groove thus allowing the O-ring to contract and a sub to be removed. 
     Removal revealed that approximately 80-90 ml of fluid had seeped into the tube section. The seepage may have occurred because the grease fittings were not holding the pressure well and leaking slowly. This may have allowed some of the squeeze to be released before the chamber could be pressurized and hold the pre-loaded seating of the O-ring. 
     SUMMARY The amount of fluid leaking into the gun section represented only approximately 1″. Notably, no surface preparation was done to the ID of the gun section to determine if the seal would hold in a worst case situation. 
     Example 2 
     PURPOSE: The test was conducted with leak proof grease fittings to determine the cause of seepage in example 1. 
     TEST SETUP: The same equipment was used as in example 1 except that the grease fitting were the leak proof design and the inside of the gun was wire brushed smooth up the section where the O-ring seats. The system was assembled and the O-rings were pressured up with a hand grease gun. Notably, the grease fittings held pressure and no fluid leakage was observed. The system was placed in a navy gun chamber and pressurized to 5000 psi and held for 20 minutes. The chamber was then depressurized and the gun system removed and disassembled. 
     RESULTS: Upon removal of one of the subs it was noted that the O-ring was deformed from apparently extruding into the gap between the wall of the gun and the OD of the sub. It was also noted that the gun had leaked approximately 180 mls of fluid which equates to approximately 1.5″ into the gun volume. 
     SUMMARY: The system held 5000 psi for 20 minutes with slight fluid seepage due to the deformation of the O-ring. Deformation is expected to be remedied by reducing the gap between the sub OD and the tube ID. In the present example, a larger than ordinary gap was used to allow for variations in the tubular&#39;s ID. 
     Example 3 
     PURPOSE: The purpose of this example is to test the pressure failure mode of the Slickwall gun system and to determine if the expandable O-ring could effect a 100% seal using a high pressure grease gun. 
     TEST SETUP: Gun Body was 16.66 inches long. This gave 12″ open gun space between the sub faces. The subs were inserted into the gun and the O-rings were expanded using a high pressure hand grease gun. The gun system was then placed into the Navy gun and pressure applied. The pressure was increased slowly until failure occurred. 
     RESULTS: Failure occurred at 9700 psi. The pressure chamber was depressurized an the gun system examined. The failure mode was “gun body collapse”. The GO plug in the top sub was removed and less than 10 MLS of water ran out of the system. 
     SUMMARY: The expandable O-ring did effect a 100% seal as evidenced by only 10 MLS of water drained from the system after collapse. It is noted that the failure pressure of 9700 psi is probably higher tant could be expected due to the short gun section. The subs probably gave added collapse strength to the system. 
     Example 4 
     PURPOSE: The purpose of this example is to determine the true collapse pressure for the 4″ Slickwall gun body. 
     TEST SETUP: A 4 foot gun section was assembled with the standard expandable O-ring top and bottom sub faces. The assembled system was placed into the Navy gun chamber and pressurized to collapse. 
     RESULTS: The gun body collapsed at 7300 psi. It should be noted that the computer collapse calculations showed the system should have collapsed at 6100 psi. 
     SUMMARY: The design requirements for the system was 5000 psi. Since the collapse failure was 7300 psi, this indicates the system has approximately a 46% safety factor. It should also be noted that in example 3 a 1 foot gun section held 9700 psi thus demonstrating the expandable O-ring is capable of nearly 10 kpsi. Pressure wise, the 4″ slickwall system has more than adequate pressure capability. 
     While the illustrative embodiments of the invention have been described with particularity, it will be understood that various other modifications will be apparent to and can be readily made by those skilled in the art without departing from the spirit and scope of the invention. Accordingly, it is not intended that the scope of the claims appended hereto be limited to the examples and descriptions set forth herein but rather that the claims be construed as encompassing all the features of patentable novelty which reside in the present invention, including all features which would be treated as equivalents thereof by those skilled in the art to which this invention pertains.