Abstract:
A dummy undersea hydraulic coupling member is disclosed for protecting an opposing undersea hydraulic coupling member when the hydraulic lines are not operating. The dummy undersea hydraulic coupling member has a water displacement expansion chamber with a piston therein that allows trapped water and/or air to move from the receiving chamber to the water displacement expansion chamber during connection of the dummy coupling member to the opposing coupling member.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    1. Field of the Invention  
           [0002]    This invention relates in general to hydraulic couplings, and specifically to hydraulic couplings used in undersea drilling and production applications. More particularly, this invention involves a dummy undersea hydraulic coupling member that is used for protecting an opposing coupling member that is stationed subsea.  
           [0003]    2. Description of Related Art  
           [0004]    Subsea hydraulic couplings are old in the art. The couplings generally consist of a male member and a female member with sealed fluid passageways connecting therebetween. The female member generally is a cylindrical body with a relatively large diameter longitudinal bore at one end and a relatively small diameter longitudinal bore at the other. The small bore facilitates connections to hydraulic lines, while the large bore seals and slidingly engages the male member of the coupling. The male member includes a cylindrical portion at one end having an outer diameter approximately equal to the diameter of the large bore in the female member of the coupling. The male member also includes a connection at its other end to facilitate connection to hydraulic lines. When the cylindrical portion of the male member is inserted into the large bore of the female member, according to various embodiments of the device, fluid flow is established between the male and female members. Several couplings of this type are shown in patents owned by National Coupling Company, Inc. of Stafford, Tex.  
           [0005]    In undersea drilling and production applications, the male member of the coupling may be connected to a manifold plate or other securement at a subsea location at the inside or outside of a well bore. In many cases, the male members are positioned so that the end or leading face of each member points vertically up from the sea floor. The female members, which also may be secured to a manifold plate, are moved into position over the male members and then lowered onto the male members by a diver or subsea vehicle, such as an ROV (remote operating vehicle). When the female members are positioned on the male members, hydraulic fluid flow typically is from the female member to the male member of each coupling. Typically, one or both of the coupling members have poppet valves.  
           [0006]    Each poppet valve typically includes a conical valve face which seats, in the closed position, against a valve seat in the coupling member. The poppet valve opens to allow fluid flow, and closes against the valve seat within the bore to arrest the flow. Generally, the poppet valve is spring-biased to the closed position. The valve may include a valve actuator which may be a nose or stem extending from the apex of the valve face along the longitudinal axis of the poppet valve.  
           [0007]    When the male and female coupling members are disconnected, the male coupling members typically remain subsea, and the female coupling members are retrieved. Frequently, well bores in which the couplings are positioned contain debris. The male member, which remains subsea when the coupling is disconnected, is subject to debris accumulating in exposed flow passages when it is disconnected from the female member. The debris may contaminate the hydraulic fluid or cause wear to the seals and sealing surfaces in the hydraulic couplings and hydraulic system. Additionally, the coupling members that remain subsea are subject to marine growth, sand, silt, and other mechanical impacts unless there is some form of protection.  
           [0008]    To reduce or prevent damage to the coupling member remaining subsea, dummy coupling members have been used. A dummy coupling member mates with the opposing coupling member, but the dummy is not connected to hydraulic lines and therefore does not function to conduct hydraulic fluid through the system. Instead, the dummy coupling member protects the opposing coupling member when the hydraulic line through that coupling is not in use.  
           [0009]    Typically, dummy undersea coupling members are the female coupling member because the male coupling member remains subsea. Dummy female coupling members may have one or more seals in a receiving chamber, and these seals engage the male member when the male member enters the receiving chamber. Dummy female coupling members also may have a bore and/or a vent passage extending between the receiving chamber and an outer surface of the dummy coupling member body. This allows trapped seawater and/or trapped air in the receiving chamber to escape out of the receiving chamber of the dummy coupling member when it engages the opposing coupling member. However, the bore or vent passage also may be subject to ingress of silt, debris, etc., with less effective protection of the opposing coupling member.  
           [0010]    Unless the trapped seawater or air is allowed to escape from the receiving chamber, it may be very difficult or impossible to fully mate the dummy coupling to the opposing coupling member. Another undesirable consequence that may occur if trapped seawater or trapped air is not allowed to escape, is due to increased pressure that may force the poppet valve of the opposing coupling member open and allow the trapped seawater or trapped air to enter the hydraulic lines. Disconnecting the dummy coupling member from the opposing member also may be difficult due to hydraulic lock.  
           [0011]    Thus, a dummy undersea hydraulic coupling member is needed to prevent debris and marine growth and other objects from damaging the coupling member remaining subsea, and which allows the dummy coupling member to be engaged and disengaged from the opposing member without resistance due to trapped seawater and/or trapped air.  
           [0012]    U.S. Pat. No. 5,692,538 to Robert E. Smith III, assigned to National Coupling Company, Inc., does not show a dummy coupling member, but shows an undersea hydraulic coupling member having angled flow passages in the body of the male member to help prevent ingress of debris. When the female member is attached to the male member, hydraulic pressure through the angled flow ports and against the face of the poppet valve urges the poppet valve of the male member open to allow fluid to flow between the coupling members. The poppet valve in combination with the angled flow ports in the male member body help prevent ingress of debris, while allowing trapped hydraulic fluid pressure to bleed off when the coupling members are disconnected.  
         SUMMARY OF THE INVENTION  
         [0013]    The present invention resides in a dummy undersea hydraulic coupling member having a water displacement expansion chamber and a piston for varying the volume of the water displacement expansion chamber in response to the pressures acting on the opposing faces of the piston. When the dummy coupling member is connected to an opposing coupling member subsea, seawater and/or air in the receiving chamber of the dummy is displaced by the opposing coupling member. That seawater and/or air enters the water displacement expansion chamber, and the piston allows the volume of that chamber to increase as a result of pressure from displaced seawater and/or air acting on the front face of the piston until the chamber reaches the volume required for a pressure equilibrium.  
           [0014]    When the dummy coupling member is disconnected from the opposing coupling member subsea, seawater pressure acting on the back face of the piston tends to urge the piston to decrease the volume of the water displacement expansion chamber, thus allowing the trapped seawater and/or air to prevent a vacuum in the receiving chamber. The piston decreases the size of the water displacement expansion chamber until it reaches the volume required for a pressure equilibrium. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0015]    The following drawings form part of the present specification and are included to further demonstrate certain aspects of the present invention. The invention may be better understood by reference to one or more of these drawings in combination with the detailed description of specific embodiments presented herein.  
         [0016]    [0016]FIG. 1 is a section view of a dummy female coupling member according to a first preferred embodiment of the present invention.  
         [0017]    [0017]FIG. 2 is a section view of a dummy female coupling member according to a second preferred embodiment of the present invention.  
     
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS  
       [0018]    Dummy coupling member  10  according to a first preferred embodiment of the present invention has first end  12  and second end  13 , and receiving chamber  11  for receiving the opposing male coupling member therein. The male member (not shown) typically is positioned on the subsea floor and in some instances faces upwardly from the subsea floor so that the leading face of the male coupling member faces upwardly. The male coupling members are commonly attached to a manifold plate using various means, such as set screws or threads, and the female coupling members often are attached to an opposing manifold plate. Techniques for attaching hydraulic coupling members to manifold plates are well known to those skilled in the art.  
         [0019]    The receiving chamber of the dummy female coupling member may have one or more seals therein for engaging and sealing with the male member. In the embodiment of FIG. 1, the dummy female coupling member includes a pressure-energized annular metal seal  17  that is retained on shoulder surface  70  by retainer  15 . The retainer may be a sleeve-shaped body threaded to the female member. Or the retainer may be a two piece retainer with one piece having a sliding interfit with cylindrical wall  28  of the receiving chamber and inserted into the receiving chamber until it abuts internal shoulder  18 , and a second piece threaded to the wall of the receiving chamber. Elastomeric seal  16  may be positioned between the two pieces. The elastomeric seal, in a preferred embodiment, has a dovetail interfit with the two-piece retainer. The receiving chamber terminates at internal shoulder  70 .  
         [0020]    Adjacent the receiving chamber is the first section  14  and second section  27  of the water displacement expansion chamber. Although the water displacement expansion chamber in the embodiment of FIG. 1 is shown having a first section with a smaller diameter and a second section with a larger diameter, the present invention also contemplates that the chamber will have a single uniform diameter, or more than two diameters if desired. In the embodiment of FIG. 1, the first section of the water displacement expansion chamber has inclined shoulder  19 .  
         [0021]    In FIG. 1, piston  20  is positioned in the second section of the water displacement expansion chamber, and abuts internal shoulder  29  absent significantly higher water or air pressure acting on front face  21  of the piston. Spring  24  urges the piston against shoulder  29 . Spring  24  is anchored by collar  25  which may be threaded or otherwise engaged to the second section of the water displacement expansion chamber adjacent second end  13  of the dummy female coupling member. The collar is a sleeve-shaped member having internal bore  26  therethrough to allow entry of water into the second section of the water displacement expansion chamber and exert pressure against rear face  22  of the piston. The piston which slides longitudinally in the water displacement expansion chamber should provide a sliding seal with the walls of the chamber, and in the embodiment of FIG. 1, annular seal  23  is shown to provide such a seal.  
         [0022]    When the dummy coupling female coupling member is connected to an opposing coupling member subsea, water and/or air in receiving chamber  11  is forced from the receiving chamber into first section  14  of the water displacement expansion chamber. The additional water and/or air pressure acting on front face  21  of piston  20  will urge the piston towards second end  13 , expanding the water displacement expansion chamber until it has sufficient volume. The piston continues to expand the water displacement expansion chamber until the pressure of water and/or air acting on the front face of the piston is balanced to the pressure of seawater and spring  24  acting on rear face  22 . In a preferred embodiment, the diameter of the piston is the same or substantially the same as the diameter of the male member entering the receiving chamber, to balance the pressure during connection and disconnection of the male member with the dummy female coupling member.  
         [0023]    When the dummy coupling member is disconnected from the opposing coupling member, a vacuum is created in the receiving chamber and the water and/or air in the water displacement expansion chamber will fill that void and avoid hydraulic lock. This results from seawater pressure acting on the rear face of the piston exceeding the pressure acting on its front face. The piston then moves toward the first end of the dummy coupling member, until the pressure is equalized.  
         [0024]    Now referring to FIG. 2, a second preferred embodiment is shown with dummy female coupling member  40  having first end  42 , second end  43  and receiving chamber  41  for connection to a male coupling member. Retainer  45  is engaged to the dummy female coupling member adjacent the first end for retaining annular metal seal  47  on shoulder  80 . Retainer may be a one-piece or two piece retainer having a first piece in sliding engagement with receiving chamber wall  58  until it abuts shoulder  48 . Elastomeric seal  47  is held between the two pieces of the retainer. The receiving chamber terminates at shoulder  81 .  
         [0025]    In the embodiment of FIG. 2, poppet valve  60  is provided in first section  44  of the water displacement expansion chamber. The poppet valve is urged by valve spring  61  into the closed position against inclined shoulder  49 . The valve spring is held by collar  62  and collar clip  63  engages the wall of the first section of the water displacement expansion chamber. In this embodiment, when the dummy female coupling member is connected to the male member, water and/or air in the receiving chamber exerts pressure against poppet valve  60  to urge the poppet valve open, entering the water displacement expansion chamber.  
         [0026]    Still referring to FIG. 2, piston  50  slides in second section  57  of the water displacement expansion chamber. Spring  54  urges front face  51  of the piston towards shoulder  59 . The piston moves in sliding relationship with cylindrical wall  57  and has annular seal  53  to seal with the wall. The spring is anchored by collar  55  adjacent second end  43  of the dummy coupling member. Seawater entering through bore  56  in collar  55  acts against rear face  52  of the piston, until the pressure on each side of the piston is balanced.  
         [0027]    Although variations in the embodiment of the present invention may not each realize all of the advantages of the invention, certain features may become more important than others in various applications of the device. The invention, accordingly, should be understood to be limited only by the scope of the appended claims.