Patent Publication Number: US-7591487-B2

Title: Apparatus and method for draining reservoirs

Description:
RELATED APPLICATIONS 
     This application claims priority to U.S. Provisional Application No. 60/518,376, which was filed on Nov. 7, 2003, the entirety of which is hereby incorporated by reference. 
    
    
     BACKGROUND OF THE INVENTIONS 
     1. Field of the Inventions 
     The present embodiments generally relate to systems and methods for draining reservoirs, and more particularly, pump assemblies for draining large reservoirs of cryogenic liquids. 
     2. Description of the Related Art 
     In the art cryogenic liquids storage, enormous storage tanks have been constructed with permanently installed high-volume pumps. For example, in the art of utility-scale liquid natural gas storage, storage tanks have been constructed with a diameter of approximately the size of half of a city block and with a height of about 175-feet. A schematic illustration of such a tank is illustrated in  FIG. 1 . 
     As shown in  FIG. 1 , a conventional liquid natural gas storage tank  10  includes an outer tank wall  12  including a generally cylindrical sidewall  14 , a flat bottom  16 , and a domed top  18 . The bottom  16  can be placed on the ground or can be suspended above the ground by pylons  20 . 
     Within the outer tank wall  12 , an inner vessel  22  is defined by an inner tank sidewall  24  and a bottom wall  26 . The sidewall  24  can be generally cylindrical in shape, corresponding to the shape of the outer wall  14 . Similarly, the bottom wall  26  can be flat corresponding with the shape of the lower wall  16 . 
     The upper end of the inner vessel  22  is open. A lid assembly  28  typically is suspended from the domed top  18  by a plurality of struts  30 . A seal  32  extends between the lid assembly  28  and the sidewall  24  of the vessel  22 . As such, the vessel  22  is sealed, and thus can store a fluid therein. In the illustrated tank  10 , the fluid within the vessel  22  includes some liquid natural gas LNG and gaseous natural gas GNG above the liquid natural gas LNG. 
     Between the outer tank wall  12  and the inner vessel  22 , insulation typically is disposed. For example, between the lower walls  16 ,  26 , a rigid insulation  34  typically is disposed. Additionally, a lighter or fluffier insulation  36  can be disposed between the lateral walls  14 ,  24 . Additional insulation can be disposed within the lid assembly  28 . Insulated as such, the tank  10  can better maintain the fluid within the vessel  22  at the desired temperature. In the art of the storage of cryogenic liquids, it is desirable to maintain the fluid at a temperature at which the liquid state of the liquid can be maintained. For example, with liquid natural gas LNG, the vessel  22  can be maintained at approximately −260° F. or lower. Other substances can be maintained in a liquid state at other temperatures. 
     As noted above, tanks such as the tank  10  are often extremely large. Additionally, such cryogenic liquids cannot be vacuumed out of such a tank. This is because when such a liquid is subject to a large vacuum, the liquid boils and therefore will not travel up a vacuum pipe and out of such a tank. Additionally, it is generally undesirable to provide a drain pipe at the bottom of such a tank  10 . If such a drain pipe were to fail, enormous amounts of liquid material, such as liquid natural gas LNG, could spill out of such a tank  10 , and thereby cause a dangerous situation. Thus, tanks such as the tank  10  typically include a pump  40  mounted near the bottom of the vessel  22  with a discharge of the pump  40  extending upwardly out of the domed top  18 . In the illustrated arrangement, the discharge pipe  42  is illustrated schematically and extends to a discharge nozzle  44  above the domed top  18 . 
     In order to provide a reasonable discharge speed of the liquid natural gas LNG, the pump  40  is quite large in size and has a high horsepower rating. Additionally, the motor  40  must be sealed and be made from a proper material to be operated in the liquid environment of the liquid natural gas LNG and at the environmental temperature of approximately −200 F. Typically, the motor  40  is suspended by the discharge pipe  42 . Thus, as noted above, because the tank can be approximately 175 ft. tall, the discharge duct  42  is made from a thick, high strength material that is appropriate for a cryogenic environment. For example, the discharge pipe  42  can be made from stainless steel or aluminum. 
     As illustrated in  FIG. 1 , the discharge pipe  42  has a lower portion that can be submerged below the level of the liquid natural gas and an upper portion, adjacent the discharge nozzle  44 , that is exposed to the atmosphere. Thus, the discharge pipe  42  is subject to substantial expansion, contraction, as well as thermal stresses. In order to prevent the discharge pipe  42  from contacting the lower surface  26  of the vessel  22 , a clearance C is defined between the lower end of the discharge pipe  42  and the lower wall  26 . In many typical tanks such as the tank  10 , the clearance C can be as much as 18 to 24 inches or more. 
     The tank  10  also includes an instrumentation assembly  50 . The instrumentation assembly  50  includes an instrument guide duct  52  extending through the domed top  18  and the lid assembly  28  into the vessel  22 , a valve  54 , an instrument head  56 , and at least one instrument  58  configured to detect a state of the material within the vessel  22 . 
     The instrument guide tube  52  can be made from any material. However, typically, the instrument guide tube  52  is made from a stainless steel pipe having an inner diameter of between 5-½ inches and 10 inches. The instrument  58  is suspended from the instrument head  56  by a cable  60 . The instrument head  56  can include a winch  62  configured to raise and lower the instrument  58  through the instrument guide tube  52 . The valve  54  can be configured to allow the instrument  58  to be retracted entirely into the instrument head  56 . For example, the valve  54  can be a “gate” type valve. With such a valve, when the valve is open, the passage extending through the valve  54  is completely open through the entire bore through the valve  54 . Alternatively, the valve  54  can be a butterfly-type valve. With a butterfly-type valve, when such a valve is open, the pivot shaft and valve plate remain within the bore of the valve  54 , thereby partially obstructing the passage therethrough. 
     When a tank such as the tank  10  reaches the end of its useful life, it is typically emptied of liquid natural gas LNG and subsequently decommissioned and/or disassembled. Initially, the liquid natural gas LNG will be pumped out of the vessel  22  by the existing pump  40 . However, as noted above, the resulting clearance C prevents the pump  40  from reaching residual liquid natural gas RLNG at the bottom of the vessel  22 . Because the clearance C can be large, as noted above, the volume of residual liquid natural gas RLNG can be quite large. 
     One way to remove the residual liquid natural gas is to allow it to evaporate out of the tank through existing plumbing. Typically, it can take approximately three months to allow such a volume of residual liquid natural gas LNG to evaporate out of the tank  10 . Additionally, such an evaporation process must be monitored to ensure public safety. Thus, the process of decommissioning a tank, such as the tank  10 , can be a long process. 
     SUMMARY OF THE INVENTION 
     In accordance with one aspect of at least one of the inventions disclosed herein, an expansion joint unit is provided comprising a pipe member, a movable connector, a fixed connector, and an anti-rotation device. The movable connector is movably disposed at one end of the pipe member and defines an opening therethrough. The fixed connector is disposed at an opposite end of the pipe member in a substantially fixed position relative to the pipe member and also defines an opening therethrough. The anti-rotation device is disposed in the pipe member, connects to the fixed connector, and comprises an opening therethrough. The anti-rotation device is configured to substantially prevent the rotation of the fixed connector relative to the movable connector. 
     In another aspect of at least one invention disclosed herein, a retrofit pump assembly for draining a reservoir is provided. The retrofit pump assembly comprises an adapter member configured for attachment to a vessel housing a fluid and an insertion tube sized for insertion through the adapter member into the vessel. The retrofit pump assembly also comprises at least one discharge pipe that connects to the adapter member and extends through the insertion tube and into the vessel. At least one sealing assembly is also provided, wherein the sealing assembly is disposed between the discharge pipe and the insertion tube and is configured to substantially prevent fluid flow through the insertion tube. The retrofit pump assembly also comprises the expansion joint unit comprising a pipe member and a movable connector connected to the at least one discharge pipe and movably disposed within the pipe member. The expansion joint unit also comprises a fixed connector connected to a pump assembly and disposed in the pipe member in a substantially fixed position relative to the pipe member. The expansion joint unit also comprises an anti-rotation device disposed in the pipe member and configured to substantially prevent the rotation of the pump assembly relative to the at least one discharge pipe. The pump assembly is disposed proximal a lower surface of the vessel, wherein the expansion joint unit is configured to allow an expansion of the at least one discharge pipe and to maintain the pump assembly substantially proximal the lower surface of the vessel. The pump assembly is configured to pump fluid from the vessel through the discharge pipe to a desired location. 
     In still another aspect of at least one of the inventions disclosed herein, a method for draining a reservoir is provided. The method comprises attaching an adapter member to a vessel that houses a fluid and sealingly inserting an insertion tube through the adapter member and into the vessel. The method also comprises sealingly inserting and advancing at least one discharge pipe through the insertion tube and into the vessel to dispose a pump assembly proximal a lower surface of the vessel. The discharge pipe is connected to a movable connector of an expansion joint unit and a fixed connector of the expansion joint unit connects to the pump assembly. The method further comprises further advancing the at least one discharge pipe through the insertion tube to move the movable connector relative to the fixed connector. Fluid is then pumped from the vessel and through the expansion joint unit and the at least one discharge pipe to a desired location. The movable connector of the expansion joint unit allows an expansion of the at least one discharge pipe and maintains the pump assembly substantially proximal the lower surface of the vessel. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic and partial sectional view of a conventional tank for storing liquid natural gas showing a pump, a discharge pipe assembly and an instrumentation assembly; 
         FIG. 2  is a schematic and partial sectional view of the conventional tank illustrated in  FIG. 1 , with the instrumentation assembly removed and with a prior art pump retrofit assembly installed thereon; 
         FIG. 3  is a schematic and partial sectional view of the tank and retrofit pump assembly illustrated in  FIG. 2  with additional sections being added to the retrofit pump assembly so that the pump is disposed at a bottom of the tank; 
         FIG. 4  is a partial schematic and sectional view of the retrofit pump assembly connected to the tank, an electronic drive for the retrofit pump, and a discharge hose for discharging liquid pumped from the tank; 
         FIG. 5  is an enlarged, schematic, and partial sectional view of the retrofit pump assembly illustrated in  FIG. 2  including an adapter mounted on the valve existing on the tank, an insertion tube extending from the adapter into the tank, a discharge pipe extending through the insertion tube with a pump assembly disposed at a lower end of the discharge pipe; 
         FIG. 6  is a perspective view of the adapter illustrated in  FIG. 5 ; 
         FIG. 7  is a top plan view of the adapter illustrated in  FIG. 6 ; 
         FIG. 8  is a side elevational view of the adapter illustrated in  FIG. 6 ; 
         FIG. 9  is a sectional view of the adapter shown in  FIG. 8  taken along line  9 - 9 ; 
         FIG. 10  is a side elevational view of the insertion tube illustrated in  FIG. 5 ; 
         FIG. 11  is a sectional view of the insertion tube illustrated in  FIG. 10  with the mounting flange removed; 
         FIG. 12  is a top plan view of the insertion tube illustrated in  FIG. 11 ; 
         FIG. 13  is an enlarged sectional view of the portion of the insertion tube identified by the circle  13  in  FIG. 11 ; 
         FIG. 14  is an enlarged portion of the insertion tube identified by the circle  14  in  FIG. 11 ; 
         FIG. 15  is a top plan view of the mounting flange of the insertion tube illustrated in  FIG. 10 ; 
         FIG. 16  is a side elevational view of the mounting flange illustrated in  FIG. 15 ; 
         FIG. 17  is a perspective view of a sealing disk mounted on the retrofit pump assembly illustrated in  FIG. 5 ; 
         FIG. 18  is a side elevational view of the sealing disk illustrated in  FIG. 17 ; 
         FIG. 19  is an enlarged view of the portion of the sealing disk of  FIG. 18  identified by the circle  19 ; 
         FIG. 20  is a top plan view of the sealing disk illustrated in  FIG. 17 ; 
         FIG. 20A  is an enlarged, schematic, and partial sectional view of an initial step in installing the retrofit pump assembly into a tank; 
         FIG. 21  is a partial sectional and side elevational view of the retrofit pump assembly illustrated in  FIG. 5  with the discharge pipe having been disconnected from the adapter and pulled partially upward out of the adapter, along with a collar holding the discharge pipe in the extracted position for aiding in assembling additional discharge pipes; 
         FIG. 22  is a side elevational view of additional discharge pipe sections to be connected to the discharge pipe illustrated in  FIG. 21 ; 
         FIG. 23  is a top plan view of the discharge pipe sectional illustrated in  FIG. 22 ; 
         FIG. 24  is an additional discharge pipe section, having a length different from that of the discharge pipe illustrated in  FIG. 22 ; 
         FIG. 25  is a top plan view of the discharge pipe section as illustrated in  FIG. 24 ; 
         FIG. 26  is an enlarged side elevational and partial sectional view of the upper end of the retrofit pump assembly having been fully installed onto the tank  10 ; 
         FIG. 27  is an enlarged side elevational view of the upper end of the discharge pipe illustrated in  FIG. 26 ; 
         FIG. 28  is a bottom plan view of a lower flange disposed at the lower end of the discharge pipe assembly illustrated in  FIG. 27 ; 
         FIG. 29  is a side elevational and partial sectional view of another retrofit pump assembly; 
         FIG. 30  is a side elevational and partial sectional view of the assembly of  FIG. 29  with the discharge pipe thereof having been drawn out of the adapter assembly along with a collar for aiding in the assembly of the discharge pipe to a further discharge pipe; 
         FIG. 31  is another embodiment of an additional discharge pipe that can be connected to the discharge pipe illustrated in  FIG. 30 ; 
         FIG. 32  is a top plan view of the discharge pipe section illustrated in  FIG. 31 ; 
         FIG. 33  is a side elevational view of another discharge pipe section having a length different from the discharge pipe section illustrated in  FIG. 31 ; 
         FIG. 34  is a top plan view of the discharge pipe section illustrated in  FIG. 33 ; 
         FIG. 35  is a side elevational and partial sectional view of the upper end of the second retrofit pump assembly being fully installed on the tank  10 . 
       The features mentioned above in the summary of the invention, along with other features of the inventions disclosed herein, are described below with reference to the drawings of the preferred embodiments. The illustrated embodiments in the figures listed below are intended to illustrate, but not to limit the inventions. The drawings contain the following additional figures 
         FIG. 35A  is a side elevational and partial sectional view of a modification of the retrofit pump assembly of  FIG. 29  including an expansion joint unit for use with the retrofit pump assembly; 
         FIG. 36  is a cross-sectional view of a modification of the expansion joint unit shown in  FIG. 35A . 
         FIG. 38A  is a cross-sectional view of a connector of the expansion joint unit. 
         FIG. 38B  is a cross-sectional view of a support member of the expansion joint unit. 
         FIG. 38C  is a cross-sectional view of an assembly of the connector illustrated in  FIG. 38A  and the support member illustrated in  FIG. 38B . 
         FIG. 38D  is an enlarged view of the portion of the connector of  FIG. 38C  identified by the circle D. 
         FIG. 38E  is a top view of an assembly of the connector shown in  FIG. 38A  and the support member shown in  FIG. 38B   
         FIG. 37A  is a cross-sectional view of a pipe member of the expansion joint unit. 
         FIG. 37B  is a cross-sectional view of a connector of the expansion joint unit. 
         FIG. 37C  is a cross-sectional view of an assembly of the pipe member shown in  FIG. 37A  and the connector shown in  FIG. 37B . 
         FIG. 37D  is an enlarged view of a cross-sectional portion of the pipe member shown in  37 C identified by the circle D. 
         FIG. 37E  is a top view of the assembly of the pipe member and connector shown in  FIG. 37C . 
         FIG. 39A  is an elevational view of an anti-rotation device of the expansion joint unit. 
         FIG. 39B  is a top view of the anti-rotation device illustrated in  FIG. 39A . 
         FIG. 39C  is a side elevational view of a beam member of the anti-rotation device illustrated in  FIG. 39A . 
         FIG. 39D  is a top view of the beam member shown in  FIG. 39C . 
         FIG. 39E  is a top view of a flange member of the anti-rotation device shown in  FIG. 39A . 
         FIG. 39F  is a cross-sectional side view of the flange member shown in  FIG. 39E . 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     With reference to  FIGS. 2-35 , a prior art retrofit pump assembly  100  is described for removing residual liquid natural gas RLNG from a conventional liquid natural gas tank  10 . The retrofit pump assembly  100  can be used with other types of tanks where it is desired to remove liquid from the bottom thereof. The retrofit pump assembly  100  provides particular benefits for use in large storage tanks for cryogenic liquids and thus is described in the environment of a liquid natural gas storage tank. However, it is to be understood that certain features, aspects, characteristics, and benefits of the retrofit pump assembly  100  can be achieved when used with other types of tanks. 
     As shown in  FIG. 2 , the instrument assembly  50  has been removed from the valve  54  and the retrofit pump assembly  100  has been inserted through the valve  54 . Where it is desired to prevent gas from exiting the vessel  22  through the guide tube  52 , the valve  54  preferably is closed during the installation of the retrofit pump assembly  100 . 
     After the initial portion of the pump assembly  100  is installed as shown in  FIG. 2 , additional sections of discharge pipe can be inserted through the valve  54  until the pump assembly at the lower end of the assembly  100  reaches the residual liquid natural gas RLNG at the bottom of the vessel  22  (See  FIG. 3 ). 
       FIG. 4  illustrates a further schematic representation of the retrofit assembly  100  being fully installed into the tank  10  and connected to a pump drive  102  and a discharge conduit  104  for directing liquid pumped from the tank  10  to a desired location. 
       FIG. 4  schematically illustrates a pump assembly  106  disposed at a lower end of the assembly  100 . The pump assembly  106  includes an electric motor  108  driving a pump  110 . The pump  110  is disposed below the motor  108  so as to achieve a lowest possible position within the tank  10  adjacent the bottom wall  26  of the tank  10 . As such, the pump  110  can remove a maximum amount of residual liquid natural gas RLNG from the vessel  22 . Preferably, the pump  110  includes an inducer to aid in feeding the pump  110  with liquid. Of course, any suitable pump  110  and motor  108  can be used. 
     The size and capacity and performance of the pump  110  and motor  108  will depend on the size of the guide tube  52 , the type of valve  54 , (i.e., full bore, such as reciprocating ball or gate-type valve, or obstructed flow, e.g., butterfly-type valve), the height of the tank  10 , the type of liquid to be pumped from the vessel  22 , and the desired flow rate. For certain typical liquid natural gas applications, the pump  110  and motor  108  preferably are configured to deliver 20 gallons per minute at 180 ft. of head. However, this is merely an exemplary pump capacity. Other pump capacities can be used depending on the desired speed. 
     The motor drive  102  is a variable frequency drive. However, this is merely one type of drive that can be used for a particular electric motor  108 . Other types of motors  108  can be used and other types of drives  102  can be used. It is to be noted that an electrical conduit  112  extending from the drive  102  to the electric motor  108  should be sealed in accordance with normal techniques well known in the art for preventing gases or liquids from traveling between the insulation of the conduit  112  and the electrical conductor extending therethrough and thereby flowing out of the tank  10  and into the junction boxes, e.g., junction boxes  114 ,  116 , or into the drive  102 . 
       FIG. 5  illustrates the retrofit assembly  100  in an initial stage of installation onto the tank  10 . As shown in  FIG. 5 , the valve  54  is a gate-type full bore valve. Thus, the passage through the valve  54  is completely unobstructed when in an open position. A valve member  120  is illustrated in a retracted position indicating an open position of the valve  54 . It is to be noted that the valve  54  is constructed in accordance with typical plumbing tolerances. Thus, the valve  54  typically will not include polished inner surfaces. Rather, the inner surfaces of the valve  54  are likely to be somewhat rough, depending on the manufacturing method used. 
     At its upper end, the retrofit assembly  100  includes an adapter member  122 . The adapter member  122  is attached to an upper end of the valve  54 . The adapter member  122  preferably includes an inner diameter that is approximately equal to that of the valve  54 . 
     An insertion tube  124  extends through the adapter  122 , the valve  54 , through the instrument guide tube  52 , and into the vessel  22  of the tank  10 . As shown in  FIG. 5 , the electric motor  108  and pump  110  are connected to a discharge pipe  126 . The discharge pipe  126  is fluidly connected with the pump  110  such that liquid discharged from the pump  110  travels around the electric motor  108  and into the discharge pipe  126  to be discharged upwardly out of the tank  10 . Typically, such a motor will include a cooling passage allowing some of the pumped liquid to be passed along the motor for cooling purposes, as is well known in the art. 
     At the point in the installation of the assembly  100  illustrated in  FIG. 5 , the discharge pipe  126  can be secured to the insertion tube  124  with a retainer member  128 . The discharge pipe  126  includes an upper flange  130  with appropriate bolt holes for receiving bolts  132  for connection to the retaining plate  128 . Additional holes on the retainer  128  are connected to an upper flange of the adapter  122  and an upper flange of the insertion tube  124 , described in greater detail below. As such, the assembly  100  can be inserted into the valve  54  and guide tube  52  as a single unit, i.e., the pump  110 , motor  108 , insertion tube  124 , and discharge pipe  126  being coupled together as a unit to be inserted into the valve  54  and the guide tube  52 . 
     The assembly  100  also includes a plurality of seal assemblies  134  configured to cooperate with the insertion tube  124  to prevent gases from within the vessel  22  from passing upwardly through the insertion tube  124  between an inner surface of the insertion tube  124  and an outer surface of the discharge pipe  126 , described in greater detail below. 
     The discharge pipe  126  can be provided with a movable seal  136  for preventing gases from passing through the pump  110 , through the discharge pipe  126  into the atmosphere. The movable seal  136  is in the form of a balloon  138  that can be inflated through an inflation conduit  140 . The conduit  140  includes a valve  142  for allowing air to be pumped into the balloon  138 , causing the balloon  130  to expand against the inner surfaces of the discharge pipe  126 , thereby forming a seal to prevent gases in the vessel  22  from passing therethrough. In the illustrated environment of a liquid natural gas vessel, the pressures within the tank  10  are relatively low, i.e., 1 to 2 pounds per square inch. Thus, the balloon  138  can be sized and configured to provide sufficient anchoring force against such a pressure while disposed within the discharge pipe  126 . 
     With reference to  FIGS. 6-9 , the adapter  122  is described in greater detail. The adapter  122  includes a pipe section  150 , an upper flange  152 , and a lower flange  154 . The pipe section  150  can be formed from standard pipe having an inner diameter approximately equal to the inner diameter of the valve  54 . With reference to  FIG. 9 , the inner surface  156  of the adapter  122  is configured to provide a seal with an outer surface of the insertion tube  124  ( FIG. 5 ). As such, the adapter  122  and the insertion tube  124  cooperate to prevent gas within the vessel  22  from passing upwardly between the outer surface of the insertion tube  124  and the inner surface  156  of the adapter  122 . 
     The adapter  122  includes an upper O-ring groove  158  and a lower O-ring groove  160 . However, this is merely one type of sealing structure that can be provided on the inner surface  156  of the adapter  122 . Other types of seals can also be used. Where the upper and lower O-ring grooves  158 ,  160  are used to form a seal with the outer surface of the insertion tube  124 , the O-ring grooves  158 ,  160  and the O-rings used therewith are chosen based on the environment of use, as is well known in the art. As noted above, the pressure within the vessel  22  can be quite low in certain environments, such as the typical pressure used in liquid natural gas containers of about 1 to 2 psi. A single O-ring groove can also be used. 
     A further advantage is provided where the adapter  122  is configured to allow the assembly  100  to be flushed. For example, the adapter  122  can be configured to allow a non-reactive gas to be circulated within at least a portion of the assembly  100  to ensure that any leak of a gas from the vessel  22  is diluted as quickly as possible as it travels up through the assembly  100 . 
     The adapter  122  includes an inlet  162  and an outlet  164 . The inlet and outlet  162 ,  164  can be connected to an inert gas circulation system (not shown). Such a circulation system can be used to circulate an inert gas, such as, for example, but without limitation, nitrogen gas, into the space between the inner surface of the insertion tube  124  and the outer surface of the discharge pipe  126 . For example, as shown in  FIG. 5 , an inert gas IG flows into the adapter  122  through the inlet  162 , circulates within a space between the inner surface of the insertion tube  124  and an outer surface of the discharge pipe  126 , and is then discharged through the outlet  164  of the adapter  122 . As such, by filling the space between the outer surface of the discharge pipe  126 , the inner surface of the insertion tube  124 , and the space above the upper-most seal  134 , any natural gas that may leak into the space is immediately diluted with the inert gas, thereby reducing the ignition potential of said gas as quickly as possible. 
     With reference again to  FIGS. 6-9 , the adapter  122  also includes a plurality of bolt holes  166  on the upper flange  152  and a plurality of bolt holes  168  on the lower flange  154 . The bolt holes  166 ,  168  are configured to provide a means for attaching the adapter  122  to the valve  54  as well as other devices, including the insertion tube  124  and the retainer  128 . 
     With reference to  FIG. 10 , the insertion tube  124  includes a pipe section  170  and a mounting flange section  172 . The pipe section  170  can be formed from any type of material suitable for the environment in which it is used. The insertion tube  124  is used in a liquid natural gas environment. Thus, the material of the insertion tube  124  should be appropriate for a cryogenic environment, which can be as cold as −260° F. Thus, for example, the pipe section  170  can be made from stainless steel or aluminum, or numerous other materials as is well known in the art. 
     In order to provide the desired seal with the inner surface  156  of the adapter  122 , and the O-rings provided in the grooves  158 ,  160 , the outer surface of the pipe section  170  should be polished as smooth as practicable. 
     With reference to  FIGS. 12-14 , sectional views of the insertion tube  124  are illustrated therein. As shown in  FIGS. 11 and 14 , a lower end  172  of the pipe section  170  includes a tapered area  174 . The tapered portion  174  comprises an area of reducing thickness along an inner surface  176  of the insertion tube  124 . This provides an additional advantage when removing the discharge pipe  126  from the insertion tube  124 . 
     With reference again to  FIG. 11 , at an upper end  178  of the pipe section  170 , an aperture  180  is disposed for allowing circulation of an inert gas as described above with reference to  FIG. 5 . 
     With reference to  FIGS. 15 and 16 , the flange portion  172  of the insertion tube  124  includes a central aperture  180  in a plurality of bolt holes  182 . The upper end  178  of the pipe section  170  can be connected to the aperture  180  through any appropriate means. For example, the upper end  178  can be connected to the aperture  180  with an interference fit. Alternatively, or in addition, the upper end  178  can be connected to the aperture  180  through bonding, welding, adhesives, and the like. The bolt holes  182  are configured to be aligned with the bolt holes  166  of the upper flange  152  of the adapter  122 . Additionally, a lower facing surface of the flange  172 , i.e., the surface of the flange  172  that abuts against the flange  152 , can include a seal, e.g., a gasket, for creating a seal against the flange  152 . 
     As noted above with reference to  FIG. 5 , the assembly  100  includes seals  134  for defining seals between the outer surface of the discharge pipe  126  and the inner surface of the insertion tube  124 . As shown in  FIG. 20 , the seals  134  comprise a disk member  190 , having a central aperture  192 , and an outer circumferential edge  194  that is configured to define a seal with the inner surface  176  of the insertion tube  124 . The outer peripheral edge  194  includes an O-ring groove  196  configured to cooperate with an O-ring (not shown) for forming an appropriate seal against the inner surface  176  of the insertion tube  124  with sufficient sealing strength to prevent the subject gas from leaking there-past. 
     The central aperture  192  is configured to form a sealing engagement with the outer surface of the discharge pipe  126 . The central aperture  192  can be sized to form an interference fit with the outer surface of the discharge pipe  126 . Alternatively, the central aperture  192  can be provided with a clearance with the outer surface of the discharge pipe  126  and then welded thereto with a continuous weld so as to form a gas tight seal. 
     A further advantage is provided where the disk member  190  includes an accessory aperture  198 . The aperture  198  is sized to allow an electrical conduit to pass therethrough. The aperture  198  is configured to allow the electrical conduit  112  to pass therethrough (See  FIG. 5 ). Optionally, the aperture  198  can be further sized to accept a sealing grommet for providing a seal between the inner surface of the aperture  198  and the outer surface of the conduit  112 . For example, as shown in  FIG. 5 , grommets  200  are illustrated as extending through the seals  134 . These grommets  200  extend through the apertures  198  illustrated in  FIGS. 17 and 20  so as to provide a seal between the inner surface of the aperture  198  and the outer surface of the conduit  112 . 
     With reference to  FIG. 20A , an initial operation for installing the assembly  100  onto the tank  10  is illustrated therein. As shown in  FIG. 20A , the valve  54  is closed such that the valve member  120  is in the deployed position and extends into the interior of the valve  54 . Additionally, the adapter  122  is bolted to the upper end of the valve  54 . A lower end of the assembly  100  is illustrated as extending through the adapter  122  such that the outer surface of the pipe section  170  of the insertion tube  124  contacts O-rings  210 ,  212  disposed in the O-ring grooves  158 ,  160  of the adapter  122 . Thus, the outer surface of the pipe section  170  is sealed to the inner surface  156  of the adapter  122 . 
     With reference to  FIG. 5 , although the assembly  100  is illustrated in a different position, it is to be noted that the seals  134  maintain a seal between the outer surface of the discharge pipe  126  and the inner surface  176  of the insertion tube  124 . Finally, it is to be noted that the balloon  138  is disposed within the interior of the discharge pipe  126 . With the assembly  100  positioned as such, the valve member  120  can be withdrawn from the valve  54 , thereby opening the valve  54  to the interior of the vessel  122 . With the valve  54  open, the assembly  100  can be slid downwardly into the guide tube  52  until it reaches the position illustrated in  FIG. 5 . 
     As noted above with reference to  FIG. 11 , the aperture  180  in the pipe section  170  is disposed at the upper end  178  of the insertion tube  124 . Thus, with the assembly  100  in the position illustrated in  FIG. 5 , the inert gas IG can be injected into the inlet  162  and then be circulated within the space above the uppermost seal  134  and between the outer surface of the discharge pipe  126  and the inner surface  176  of the insertion tube  124 . After any circulation of inert gas is performed, the retainer  128  can be removed. For example, with reference to  FIG. 21 , the retainer  128  has been removed and the discharge pipe  126  has been pulled upwardly from the insertion tube  124 . Another retainer  230  is illustrated as supporting the discharge pipe  126  against the mounting flange  172  of the insertion tube  124 . 
     As such, the retainer  230  supports the weight of the discharge pipe  126 , the electric motor  108 , and the pump  110 . Thus, an additional discharge pipe  126 A can be connected to the upper end of the discharge pipe  126 . Prior to connecting the additional discharge pipe  126 A to the discharge pipe  126 , the air filling tube  140  can be threaded through the discharge pipe  126 A. After connecting the discharge pipe  126 A, the retainer  230  can be removed and the two discharge pipes  126 ,  126 A can be lowered down into the vessel  22 . During or after the discharge pipes  126 ,  126 A have been lowered further into the insertion tube  124 , the balloon  138  can be moved upwardly through the discharge pipe  126 A. For example, the balloon  138  can be partially deflated by releasing some of the air from within the balloon through the valve  142 . Once the balloon  138  is dislodged, the balloon  138  can be slid upwardly through the discharge pipe  126 A until it reaches a position near the upper end thereof. At that point, additional air can be reinserted into the balloon  138  to secure its position and continue to provide a seal against the outflow of gas from the vessel  22 . 
     Additionally, as the discharge pipes  126 ,  126 A are lowered into the insertion tube  124 , the inert gas IG can continuously be circulated within the spaces between the seals  134  and the outer surface of the discharge pipes  126 ,  126 A and the inner surface  176  of the insertion tube. As such, the atmospheric air that initially is drawn into the insertion tube  124  as the discharge pipes  126 ,  126 A are lowered into the tube  124 , is continuously diluted. Of course, if desired, the discharge pipes  126 ,  126 A can be stopped at various positions wherein the seals  134  define discrete chambers within the insertion tube  124  such that these discrete chambers are in communication with the inlet and outlet  162 ,  164  so as to completely dilute and refill these chambers with an inert gas. As such, the inert gas prevents any air fuel mixtures forming where the gas within the vessel  22  is a potential fuel. 
     It is to be noted also that the conduit  112  can be made from a single piece of conduit and continuously thread through the seals  134  and grommets  200  as additional discharge pipe sections  126 ,  126 A are connected together. With reference to  FIGS. 22-25 , exemplary discharge pipes  126 ,  126 A are illustrated therein. 
     As shown in  FIG. 22 , the discharge pipes  126 ,  126 A can comprise a commercially available one and one-half inch (1½″) pipe  240 . Of course, the type of pipe  240  used can be changed in accordance with the environment of use, as is well known in the art. 
     The discharge pipes  126 ,  126 A also include mounting flanges  242  at both the upper and lower ends thereof. The mounting flanges  242  can comprise commercially available flanges for standard piping. 
     With reference to  FIG. 23 , each of the flanges  242  include a notch  244  for allowing the electrical conduit  112  to extend thereby. Additionally, each of the flanges  242  include apertures  246  for receiving bolts for connecting the flanges  242  to the flanges  242  of adjacent discharge pipes  126 ,  126 A. 
       FIGS. 24 and 25  illustrate a shorter discharge pipe  126 ,  126 A which may be used in conjunction with the longer discharge pipes  126 ,  126 A illustrated in  FIG. 22 . This provides greater flexibility in installing the assembly  100  into the tank  10 . For example, the discharge pipes  126 ,  126 A illustrated in  FIG. 22  can be a standard length, for example, but without limitation, 10 feet long. Thus, if it is desired to reach a depth into the tank  10  that is not a multiple of 10 feet, another size discharge pipe  126 ,  126 A can be used to reach the final depth. 
     Optionally, the flanges  242  can be provided with seals similar to that of the seals  134 . As such, the assembly  100  provides further sealing against the leaking of gas from the vessel  22  to the atmosphere. 
     With reference to  FIG. 26 , as the final depth is approached, a final discharge pipe assembly  300  can be connected to the top of the previously installed discharge pipe  126 A. As shown in  FIG. 26 , a lower end of the final discharge pipe  300  includes a standard flange  242  which can be identical to the uppermost flange  242  of the discharge pipe  126 A. Thus, a further description of the connection therebetween is not described further. 
     At its upper end, the final discharge pipe  300  can include a headplate  302  which is configured to form a complete seal over the upper flange  156  of the adapter  122 . The headplate  302  can include a gland nut assembly  304  for sealing the outer surface of the final discharge pipe assembly  300  against an aperture formed in the headplate  302 . As such, the final depth of the pump  110  within the tank  10  can be adjusted on site. Then, once the final depth is reached, the gland nut assembly  304  can be tightened to thereby provide a gas tight seal at the upper end of the adapter  122 . 
     The upper end of the final discharge pipe  300  also includes a valve  306 . The valve  306  can be configured to allow the balloon  138  to pass therethrough after the final discharge pipe  300  has been secured to the headplate  302 . Thus, with the valve  306  open, the balloon  138  can be pulled to the position illustrated in  FIG. 26  in a slightly deflated state. After the balloon has reached the position illustrated in  FIG. 26 , the valve  306  can be closed and the balloon  138  can be removed. As such, the balloon  138  can be used to maintain a seal of the discharge pipe assemblies during the installation process. 
       FIGS. 27 and 28  illustrate the final discharge pipe assembly  300  in greater detail. 
     With reference to  FIG. 29 , a further advantage is provided where each discharge pipe assembly  126  is provided with a valve  310  that can replace the balloon  138 . For example, as shown in  FIG. 29 , the discharge pipe  126 ′ includes a valve  310 . The valve  310  can be any type of valve to be installed in-line along the pipe forming the discharge pipe  126 ′. At the stage of installation illustrated in  FIG. 29 , which corresponds generally to the position illustrated in  FIG. 5 , the valve  310  is closed. Thus, no gas from the vessel  22  can escape. 
     With reference to  FIG. 30 , after the retainer  128  has been removed and the retainer  230  has been installed, the discharge pipe  126 A′ can be connected to the upper end of the discharge pipe  126 ′. At this point, the valve  310 A of the discharge pipe  126 A′ is closed. Thus, the valve  310  on the discharge pipe  126 ′ can be opened. As such, the valve  310 A maintains the seal within the discharge pipe to prevent the discharge of any fluids from the tank  10 . As such, the valves  310 ,  310 A provide further protection against leaks of fluid from the vessel  22 . For example, it is known that a balloon such as the balloon  138  can be operated improperly and thus, due to human error, can be allowed to slip out. However, if one of the valves  310 ,  310 A are accidentally left open, they can simply be closed. 
     With reference to  FIGS. 31-34 , further detail of the discharge pipes  126 ′,  126 A′ are illustrated therein. However, no further description of  FIGS. 31-34  are necessary for one of ordinary skill in the art to make and use the inventions disclosed herein. 
       FIG. 35  illustrates a final discharge pipe  300 ′ installed in the assembly  100 . The final discharge pipe  300 ′ can be constructed in accordance with the description of the final discharge pipe  300  illustrated in  FIGS. 26-28 . Thus, no further description of the discharge pipe  300 ′ is necessary for one of ordinary skill in the art to make and use the inventions disclosed herein. 
     With reference to  FIG. 35A , a further advantage can be achieved by including an “expansion joint” in the assembly  100 , in accordance with at least some of the inventions disclosed herein. In the illustrated embodiment, the expansion joint can be disposed in the discharge pipe  126  above the electric motor  108 . A schematic illustration of an expansion joint in  FIG. 35A  is identified generally by the reference numeral  312 . 
     Such expansion joints are commercially available for non-cryogenic uses. However, because this joint will be placed inside the tank  10  during use, the joint  312  can leak during use. Of course, it is preferable that such an expansion joint be optimized so as not to leak during use. Preferably, the expansion joint  312  will allow the discharge pipe  126 ′ to expand enough so that the pump  110  remains on the lower surface  26  of the vessel  22 . The dome  18  can rise about one foot due to the thermal expansion of the outer walls  14  caused by the change of night to day when sunlight strikes, and thereby expands, the walls  14 . As such, the adapter  122  rises by the same amount, thereby causing the pump  110  to move away from the bottom  26  of the vessel  22 . 
     Thus, in the illustrated embodiment, the expansion joint  312  can allow the pipe  126 ′ to expand about one foot, thereby allowing the pump  110  to remain as close to the bottom  26  as possible. 
       FIG. 36  illustrates another embodiment of an expansion joint unit  312 , identified generally by the reference numeral  312 ′. The expansion joint unit  312 ′ preferably comprises a pipe member  320  sized to receive a fixed connector  330  and a movable connector  340  therein. In this embodiment, the movable connector  340  is sized to slidingly move within the pipe member  320 . In  FIG. 36 , the arrow E identifies the extension direction and the arrow R identifies the retracting direction of the expansion joint unit  312 ′. 
     The movable connector  340  is preferably fastened to a support member  350  and houses a seal  360  therebetween, as is further described below. Additionally, a retaining member  365  is preferably disposed on the pipe member  320  to substantially limit the motion of the movable member  340 .  FIG. 36  illustrates the fully extended position of the expansion joint  312 ′. In the fully extended position, the moveable connector  340  abuts against the retainer member  365 . In the fully retracted position, the moveable connector  340  abuts against the fixed connector  330 . An intermediate position of the moveable connector  340  (in phantom line) is also illustrated in  FIG. 36 . 
     In some embodiments, the retaining member  365  can comprise a snap ring. However, in other embodiments, the retaining member  365  can be any structure configured to substantially limit the motion of the movable member  340 , such as a detent or protrusion on the pipe member  320 . 
     A further advantage is provided where the expansion joint unit  312 ′ comprises an anti-rotation device  370  configured to prevent rotation of the lower end of the assembly relative to the upper portion of the assembly  100 . For example, the pump  110  can include a shaft rotating about a vertical axis. Thus, the pump  110  can generate a torque, tending to cause the lower end of the discharge pips  126 ′ to rotate relative to the upper end of the discharge pipe  126 ′. If this rotation occurs, the conduit  112  would be the only structure that could resist such a rotating motion, thereby imparting an undesirable stress on the conduit  112 . Thus, by including an anti-rotation device in the expansion joint  312 ′, such undesirable stresses can be avoided. 
     In some embodiments, the anti rotation device  370  can be fastened to the fixed connector  330  via fasteners  380 . In the illustrated embodiment, the fasteners  380  consist of bolts. However, in other embodiments, the anti-rotation device  370  can be fastened to the fixed connector  330  using other fastening mechanisms, such as screws, adhesives, or welds. In still another embodiment, the fixed connector  330  and anti-rotation device  370  and be an integral unit. 
     In the illustrated embodiment, a fixation member  390  is disposed between at least a portion of the fixed connector  330  and the pipe member  320 , as discussed further below. The fixation member  390  preferably maintains the fixed connector  330  in a substantially fixed position relative to the pipe member  320 . In the illustrated embodiment, the fixation member  390  consists of at least one set screw. In other embodiments, the fixation member  390  can be a weld disposed between the fixed connector  330  and the pipe member  320 . In another embodiment, the fixation member  390  can be an adhesive disposed between the fixed connector  330  and the pipe member  320 . In still another embodiment, the fixed connector  330  can be connected to the pipe member  320  via a press-fit connection. 
     With reference to  FIGS. 37A-E , the pipe member  320  and fixed connector  330  of the expansion joint unit  312  are illustrated in greater detail. As shown in  FIG. 37A , the pipe member  320  has a length L 1  that extends between a proximal end  320   a  and a distal end  320   b  of the pipe member  320 . 
     The proximal end  320   a  preferably connects to the movable connector  340 , as shown in  FIG. 36 . Similarly, the distal end  320   b  preferably connects to the fixed connector  330 . 
     With reference to  FIGS. 37A-D , the pipe member  320  defines an inner surface  320   c  that preferably extends circumferentially about an axis X 1  of the pipe member  320  at a diameter  320   d . In the illustrated embodiment, the inner surface  320   c  is preferably a cylindrical surface, with a circular cross-section. However, in other embodiments the inner surface  320   c  can have other cross-sectional shapes, such as square or polygonal, with a corresponding effective diameter  320   d.    
     As shown in  FIGS. 37C and 37D , the pipe member  320  preferably comprises a slot  322  on the inner surface  320   c  and disposed substantially at the proximal end  320   a  of the pipe member  320 . The slot  322  preferably receives the retaining member  365  therein. In one embodiment, the slot  322  lockingly engages the retaining member  365 . Preferably, the slot  322  extends substantially continuously along the inner surface  320   c  of the pipe member  320 . In another embodiment, the slot  322  can consist of a number of discreet slots  322  disposed along the inner surface  320   c  of the pipe member  320 . 
     As shown in  FIG. 37A , the inner surface  320   c  of the pipe member  320  also defines a recess  324  having a diameter  324   a  at the distal end  320   b  of the pipe member  320 . Preferably, the diameter  324   a  of the recess  324  is greater than the diameter  320   d  of the inner surface  320   c . In the illustrated embodiment, the recess  324  extends substantially continuously about the circumference of the inner surface  320   c . In another embodiment, the recess  324  consists of discreet recesses  324  disposed about the circumference of the inner surface  320   c.    
     With reference to  FIG. 37B , the fixed connector  330  extends from a proximal end  330   a  to a distal end  330   b , and has inner and outer surfaces  332 .  334 . In the illustrated embodiment, at least a portion of the inner surface  332  has a first diameter  332   a,  and at least second portion of the inner surface  332  has a second diameter  332   b.  Preferably, the second diameter  332   b  is greater than the first diameter  332   a,  so as to define a retaining surface  332   c  on the inner surface  332 . 
     Likewise, at least a portion of the outer surface  334  has a first diameter  334   a , at least a second portion of the outer surface  334  has a second diameter  334   b , and at least a third portion of the outer surface  334  has a third diameter  334   c . Preferably, the first diameter  334   a  is greater than the second diameter  334   b , so as to define a first retaining surface  335   a , and the second diameter  334   b  is greater than the third diameter  334   c , so as to define a second retaining surface  335   b . In another embodiment, the diameters  334   a ,  334   b ,  334   c  can have substantially the same dimension. In still another embodiment, at least two of the diameters  334   a ,  334   b ,  334   c  can have the same dimension. 
     In the illustrated embodiment, the inner surface  332  defines a passage  336  through the fixed connector  330 . Preferably, the passage  336  consists of a proximal section  336   a  and a distal section  336   b . In one embodiment, the first diameter  332   a  of the inner surface  332  defines the proximal section  336   a . Likewise, the second diameter  332   b  of the inner surface  332  defines the distal section  336   b . Additionally, at least one fastener opening  338  is formed on the proximal end  330   a  of the fixed connector  330 . The fastener openings  338  preferably receive the fasteners  380  therein, as discussed above and shown in  FIG. 36 . For example, in one embodiment the fastener openings  338  can have a threaded surface that engages a corresponding thread on the fasteners  380 . 
     As illustrated in  FIG. 37C , the first diameter  334   a  of the outer surface  334  is preferably about the same dimension as the inner diameter  320   d  of the pipe member  320 . In one embodiment, the first diameter  334   a  can be slightly larger than the inner diameter  320   d  of the pipe member  320  so that the fixed connector  330  and pipe member  320  are joined via a press-fit connection. In another embodiment, the first diameter  334   a  is smaller than the inner diameter  320   d  of the pipe member  320 . With the fixed connector  330  disposed in the pipe member  320 , at least one of the portions of the outer surface  334  having second and third diameters  334   b ,  334   c  defines a slot  326  between the pipe member  320  and the fixed connector  330 , as shown in  FIG. 37C . The slot  326  preferably receives the fixation member  390 , as discussed above. In a preferred embodiment, the slot  326  extends substantially continuously about the circumference of the fixed connector  330 . In another embodiment, the slot  326  consists of a number of discreet slots  326  disposed circumferentially about the outer surface  334  and between the fixed connector  330  and the pipe member  320 . 
     In the illustrated embodiment, as shown in  FIGS. 37B  and C, the distal section  336   b  of the passage  336  preferably receives at least a portion of the pump assembly  106  therein. In one embodiment, said portion of the pump assembly  106  extends into the distal section  336   b  so as to contact the retaining surface  332   c . In another embodiment, the portion of the inner surface  332  having second diameter  332   b  can be threaded to engage a corresponding threaded surface on the pump assembly  106 . In still another embodiment, said portion of the pump assembly  106  can be press-fit to the distal section  336   b  of the passage  336 . In yet another embodiment, the pump assembly  106  can be welded to the distal section  336   b  of the passage  336 . 
     As shown in  FIGS. 37E , the inner and outer surfaces  332 ,  334  of the fixed connector  330  are preferably circular. However, in other embodiments the inner and outer surfaces  332 ,  334  can have other shapes, such as square and polygonal. Preferably, the outer surface  334  has the same shape as the inner surface  320   d  of the pipe member  320 . Similarly, the inner surface  332  that defines the distal section  336   b  of the passage  336  preferably has the same shape as the portion of the pump assembly  106  that is inserted therein. 
       FIGS. 38A-E  further illustrate the movable connector  340  of the expansion joint unit  312 . As illustrated in  FIG. 38A , the movable connector  340  extends between a proximal end  340   a  and a distal end  340   b  and preferably comprises a base  342  at the distal end  340   b . In the illustrated embodiment, the base  342  defines at least one fastener opening  342   a  and a primary opening  342   b , wherein the openings  342   a ,  32   b  extend through the base. Each fastener opening  342   a  preferably receives a fastener  400  therethrough (see  FIG. 38C ). As shown in  FIG. 38C , the fastener  400  can be a threaded anchor. However, in other embodiments, the fasteners  400  can be dowels, bolts, screws, adhesives, welds, brackets, braces or any other fastening mechanisms suitable for use in a cryogenic environment. 
     Likewise, the primary opening  342   b  preferably slidingly receives the anti-rotation device  370  therethrough. As shown in  FIG. 38E , the base  342  preferably has at least one slot  342   c  formed therein that extends outward from the primary opening  342   b . Said slots  342   c  preferably receive the anti-rotation device  370  therethrough, as further discussed below. 
     As best illustrated in  FIG. 38D , the base  342  also preferably has a chamfer  342   d  at the distal end  340   b  of the movable connector  340  that is oriented at an angle α relative to the base  342 . The chamfer  342   d  can be at any angle. 
     With reference to  FIG. 38A , the movable connector  340  also preferably comprises a circumferential wall  344  that extends from the base  342  to a free end at the proximal end  340   a  of the movable connector  340 . The wall  344  has an inner surface  344   a  with an inner diameter  344   b , and an outer surface  346  with an outer diameter  346   a . The inner surface  344   a  and the base  342  define a cavity  347  therebetween. 
     In the illustrated embodiment, at least one protrusion  348  having a width  348   a  extends outward from the outer surface  346  of the wall  344  to an outer diameter  348   b . In one preferred embodiment, the protrusion  348  extends substantially continuously about the circumference of the outer surface  346  and the width  348   a  extends radially outward from the outer surface  346  of the wall  344 . In another embodiment, the protrusion  348  consists of a number of discrete protrusions  348  that extends radially outward from the outer surface  346  of the wall  344 . Preferably, the outer diameter  348   b  of the protrusion  348  is smaller than the inner diameter  320   d  of the pipe member  320 , so that the movable connector  340  can slidably move within the pipe member  320 . 
     In some embodiments, the cavity  347  receives one end of the discharge pipe  126 ′ therein. The inner diameter  344   b  of the wall  344  is generally about the same dimension as the outer diameter of the discharge pipe  126 ′. In another embodiment, the inner diameter  344   b  of the wall  344  can be slightly smaller than the outer diameter of the discharge pipe  126 ′ to join the movable connector  340  and the discharge pipe  126 ′ via a press-fit connection. In still another embodiment, the inner surface  344   a  can be threaded to engage a corresponding thread on the outer surface of the discharge pipe  126 ′. In yet another embodiment, the inner surface  344   a  of the movable connector  340  can be welded to the outer surface of the discharge pipe  126 ′. In still other embodiments, the movable connector  340  can be fastened to the discharge pipe  126 ′ via other fastening mechanisms, such as bolts, screws, adhesives, brackets and braces. 
       FIG. 38B  illustrates a support member  350  that is preferably fastened to the base  342  of the movable connector  340 . In another embodiment, the support member  350  and movable connector  340  can be manufactured as an integral unit. The support member  350  has a diameter  352  that is preferably smaller than the inner diameter  320   d  of the pipe member  320 , so that the support member  350  slidably moves within the pipe member  320 . In the illustrated embodiment, the support member  350  has a diameter  352  of approximately the same dimension as the outer diameter  348   b  of the protrusion  348 . However, in other embodiments, the support member  350  can have a diameter  352  smaller or larger than the diameter  348   b  of the protrusion  348 . 
     The support member  350  comprises a number of fastener openings  354  therethrough, wherein each opening  354  can be aligned with the corresponding fastener opening  342   a  in the base  342  of the movable connector  340 . The support member  350  also comprises a primary opening  356  that preferably aligns with primary opening  342   b  in the base  342  of the movable connector  340  when the movable connector  340  and the support member  350  are adjacent each other. The support member  350  also preferably comprises at least one slot  358  formed therein and extending outward from the primary opening  356 , wherein said primary opening  356  and slots  358  slidingly receive the anti-rotation device  370  therethrough. 
       FIG. 38C  illustrates an assembly of the movable connector  340  and support member  350 . In the illustrated embodiment, the fasteners  400  extend through the fastener openings  342   a ,  354  to connect the movable connector  340  and support member  350  together. Though the illustrated embodiment shows the fasteners  400  as threaded inserts, the fasteners  396  can comprise other fastening mechanisms, as discussed above. 
     With further reference to  FIG. 38C , the protrusion  348  defines a space  359  between the support member  350  and movable connector  340 . In a preferred embodiment, the sealing member  360  is disposed in the space  359 , as shown in  FIG. 36 . In one embodiment, the seal  360  comprises Teflon rope. However, in other embodiments, the seal  360  can be made of other materials suitable for used in cryogenic environments. Preferably, the seal  360  substantially prevents the leakage of fluid through the space  359  between the support member  350  and the protrusion  348  of the movable connector  340 . 
       FIG. 38D  shows an enlarged view of a section of the base  342  of the movable connector  340 . Preferably, the chamfer  342   d  defines a slot  349  between the base  342  and the support member  350  when the support member  350  is adjacent the movable connector  340 . In a preferred embodiment, the slot  349  receives a seal disposed between the movable connector  340  and the support member  350 . In another embodiment, the slot  349  can receive a weld therein to fasten the support member  350  to the movable connector  340  and substantially prevent leakage of fluid through the slot  349 . 
       FIG. 38E  shows a top view of the support member  350  and movable connector  340  assembly. In the illustrated embodiment, the slots  342   c  disposed along the periphery of the primary opening  342   b  of the movable connector  340  and the slots  358  disposed around the periphery of the primary opening  356  of the support member  350 , are substantially aligned with each other. The slots  342   c ,  358  preferably receive at least a portion of the anti-rotation device  370  therethrough. Although the illustrated embodiment shows four slots  342   c ,  358  in the primary openings  342   b ,  356  of the movable connector  340  and support member  350 , respectively, the number of slots  342   c ,  358  can be fewer or greater. 
       FIG. 37E  also illustrates the position of the fastener openings  342   a ,  354  in the movable connector  340  and support member  350 . Although four fastener openings  342   a ,  354  are shown, the movable connector  340  and support member  350  can have fewer or more fastener openings  342   a ,  354 . 
       FIGS. 39A-F  further illustrate one embodiment of an anti-rotation device. In the illustrated embodiment, the anti-rotation device  370  comprises an elongated beam member  372  that extend between a proximal end  372   a  and a distal end  372   b  and defines a length L 2  therebetween. Preferably, the beam member  372  extends about an axis X 2 . 
     As shown in  FIG. 39D , in the illustrated embodiment the beam member  372  has a cross-section generally in the shape of a cross extending from a center  372   c  to ends  372   d . Preferably, the ends  372   d  are sized to slidably move within the slots  342   c ,  358  of the movable connector  340  and support member  350 . Additionally, the ends  372   d  are preferably sized to have an effective diameter  372   e  that is lower than the inner diameter of the discharge pipe  126 ′. However, the beam member  372  can have other cross-sectional shapes, such as square, triangular, or polygonal. 
     With reference to  FIGS. 39B , and E-F, the anti-rotation device  370  also preferably comprises a base  374  with a diameter  374   a  that connects to the distal end  372   b  of the beam member  372 . In the illustrated embodiment, the base  374  connects to the beam member  372  via a weld. In other embodiments, the base  374  can be connected to the beam member  372  with other fastening mechanisms, such as adhesives, bolts, screws, brackets or braces. In still another embodiment, the base  374  and beam member  372  can be an integral unit. 
     The diameter  374   a  of the base  374  preferably has approximately the same size as the first diameter  334   a  of the outer surface  334  of the fixed connector  330 . In another embodiment, the diameter  374   a  of the base  374  can be lower than the first diameter  334   a  of the fixed connector  330 . In another embodiment, the diameter  374   a  of the base  374  can be greater than the first diameter  334   a  of the fixed connector  330 . Additionally, the diameter  374   a  of the base  334  is preferably approximately the same size as the inner diameter  320   d  of the pipe member  320 . 
     The base  374  preferably defines a number of primary openings  374   b  disposed about a center  374   c  of the base  374  on either side of arms  374   d  of the base  374 . In a preferred embodiment, the arms  374   d  of the base  374  support the ends  372   d  of the beam member  372  and the center  372   c  of the beam member  372  generally aligns with the center  374   c  of the base  374 . Though the illustrated embodiment shows four primary openings  374   b  having a generally triangular shape, the base  374  can have more or fewer primary openings  374   b  having other shapes suitable for allowing fluid flow therethrough. 
     The base  374  also preferably defines fastener openings  374   e  disposed circumferentially along the base  374  and sized to receive the fasteners  380  as discussed above. The fastener openings  374   e  preferably align with corresponding fastener openings  338  on the fixed connector  330  of the expansion joint unit  312 , as illustrated in  FIGS. 36 , and  37 B, E. Though the illustrated embodiment shows four fastener openings  374   c , the base  374  can have more or fewer fastener openings  374   e.    
     The expansion joint unit  312  is preferably made of materials suitable for use in cryogenic environments. For example, in one embodiment, the expansion joint unit  312  can be made of stainless steel. In another embodiment, the expansion joint unit  312  can be made of aluminum. In other embodiments, the expansion joint unit  312  can be made of high strength materials appropriate for a cryogenic environment. 
     During use, the expansion joint unit  312  can better maintain the pump  110  in contact or in close proximity with the lower surface  26  of the vessel  22 . For example, during operation, the expansion joint unit  312  is preferably fastened to the discharge member  126 ′ and to the pump assembly  106 , as described above. The discharge member  126 ′, expansion joint unit  312 , and pump assembly  106  are then lowered into the vessel  22  until the pump  110  substantially contacts the lower surface  26  of the vessel  22 . 
     Preferably, the discharge member  126 ′ is further lowered so that the movable connector  340 , to which the discharge member  126 ′ is attached, movably slides within the pipe member  320  of the expansion joint unit  312 , and so the beam member  372  of the anti-rotation device  370  extends into the discharge member  126 ′. 
     In a preferred embodiment, the discharge member  126 ′ is lowered about one foot into the pipe member  320  of the expansion joint unit  312 . In another embodiment, the discharge member  126 ′ can be lowered less than one foot into the pipe member  320  of the expansion joint unit  312 . In still another embodiment, the discharge member  126 ′ can be lowered less than one foot into the pipe member  320  of the expansion joint unit  312 . In yet another embodiment, the discharge member  126 ′ can be lowered into the pipe member  320  of the expansion joint unit  312  by at least an amount corresponding to the expected rise of the dome  18  of the vessel  22  due to thermal expansion. Accordingly, as the dome  18  of the vessel  22  rises due to thermal expansion, as discussed above, said expansion also causes the discharge pipe  126 ′ to withdraw from the expansion joint unit  312 . However, in a preferred embodiment said withdrawal of the discharge pipe  126 ′ does not displace the pump  110  from the lower surface  26  of the vessel  22 . 
     The expansion joint unit  312  preferably also substantially prevents the rotation of the pump assembly  106  relative to the discharge pipe  126 ′. As discussed above, the ends  372   d  of the beam member  372  preferably slidably move within the slots  342   c ,  358  of the movable connector  340  and support member  350 . Accordingly, the ends  372   d  and slots  342   c ,  358  operate as a key and keyway system, preventing the rotation of the beam member  372  within the pipe member  320 . Accordingly, any rotational force generated by the electric motor  108  does not cause the rotation of the anti-rotation device  370  relative to the discharge pipe  126 ′. 
     The expansion joint unit  312  preferably allows the pump  110  to remove RLNG from the vessel  22 . The RLNG preferably flows through the passage  336  of the movable connector  330 . The RLNG then flows through the primary openings  374   b  of the base  374  of the anti-rotation device  370 . Subsequently, the RLNG passes through the pipe member  320  and the primary openings  342   b ,  356  of the movable connector  340  and support member  350 . The RLNG then flows into the discharge pipe  126 ′ for withdrawal from the vessel  22  as described above. 
     Although the inventions disclosed herein have been disclosed in the context of certain preferred embodiments and examples, it will be understood by those skilled in the art that the inventions disclosed herein extend beyond the specifically disclosed embodiments to other alternative embodiments and/or uses of the inventions and obvious modifications and equivalents thereof. Thus, it is intended that the scope of the inventions disclosed herein should not be limited by the particular disclosed embodiments described above, but should be determined only by a fair reading of the claims that follow.