Abstract:
The present application teaches fire-resistant structures and methods for wellhead outlets, and methods of using same. In one embodiment, the fire-resistant structure includes a plurality of spacing assemblies ( 32   a - f ) that space a plurality of fire-resistant panels ( 42, 44, 46, 48, 49, 50, 53, 55 ) away from the exterior surface of a wellhead outlet ( 1 ), such that a space or volume is created between the fire-resistant panels ( 42, 44, 46, 48, 49, 50, 53, 55 ) and the exterior surface of the wellhead outlet ( 1 ).

Description:
FIELD OF THE INVENTION 
       [0001]    The present invention relates to fire-resistant structures and methods of using same, and more particularly to fire-resistant structures and methods for wellhead outlets and methods of using same. 
       BACKGROUND OF THE INVENTION 
       [0002]    A wellhead is a component used at the surface of an oil or gas well that provides structural and pressure-containing interface for the drilling and production equipment. Wellheads are often welded to the first string of casing, which has been cemented in place over the well. Thus, wellheads often form an integral part of a well once initially installed. 
         [0003]    Because oil and gas are highly flammable and because the environments in which oil and gas wells are located are often dangerous, it is desirable to provide adequate safety measures to protect wellheads and surrounding structures from potentially-damaging fires. Accordingly, there is a need for fire-resistant structures for wellhead outlets and methods of using same. 
       ASPECTS OF THE INVENTION 
       [0004]    Additional aspects of the invention include: 
         [0005]    Aspect 1: A kit for retrofitting an existing wellhead outlet, the existing wellhead outlet having at least one exterior surface, the kit comprising at least one spacing assembly, the at least one spacing assembly being attachable at a first end thereof to the at least one exterior surface of the existing wellhead outlet, the at least one spacing assembly further comprising a second end that is spaced apart from the first end; and at least one panel that is attachable to the second end of the at least one spacing assembly. 
         [0006]    Aspect 2: The kit according to Aspect 1, wherein the at least one panel is comprised of a flame-retardant ceramic material. 
         [0007]    Aspect 3: The kit according to either of Aspect 1 or Aspect 2, wherein the at least one spacing assembly is comprised of an insulated material. 
         [0008]    Aspect 4: The kit according to any of Aspects 1-3, wherein each of the at least one panel has a planar exterior surface. 
         [0009]    Aspect 5: The kit according to any of Aspects 1-4, wherein the at least one panel and at least one spacing assembly can fully enclose the wellhead outlet, except for any port that extends from the wellhead outlet. 
         [0010]    Aspect 6: The kit according to any of Aspects 1-5, wherein the at least one spacing assembly includes at least one removable fastener that attaches the at least one spacing assembly to the wellhead outlet. 
         [0011]    Aspect 7: An apparatus comprising: a wellhead outlet having at least one exterior surface; and at least one panel attached to the at least one exterior surface of the wellhead outlet such that the at least one panel is spaced apart from the at least one exterior surface of the wellhead outlet. 
         [0012]    Aspect 8: The apparatus according to Aspect 7, wherein the at least one panel is comprised of a flame-retardant ceramic material. 
         [0013]    Aspect 9: The apparatus according to either of Aspect 7 or Aspect 8, further comprising at least one spacing assembly attached to both the at least one panel and the at least one exterior surface of the wellhead outlet and acts to space the at least one panel apart from the at least one exterior surface of the wellhead outlet. 
         [0014]    Aspect 10: The apparatus according to Aspect 9, wherein the at least one spacing assembly is comprised of an insulated material. 
         [0015]    Aspect 11: The apparatus according to any of Aspects 7-10, wherein the at least one panel can fully enclose the wellhead outlet, except for any port that extends from the wellhead outlet. 
         [0016]    Aspect 12: The apparatus according to any of Aspects 7-11, wherein the at least one panel is attached to the at least one exterior surface of the wellhead outlet using at least one removable fastener. 
         [0017]    Aspect 13: A method of protecting a wellhead outlet, the wellhead outlet having at least one exterior surface, the method comprising: attaching one or more spacing assemblies to the at least one exterior surface of the wellhead outlet; and attaching one or more panels to the one or more spacing assemblies such that the one or more panels are spaced apart from the at least one exterior surface of the wellhead outlet. 
         [0018]    Aspect 14: The method according to Aspect 13, further comprising the step of tapping a threaded hole into the at least one exterior surface of the wellhead outlet, wherein the step of attaching one or more spacing assemblies to the at least one exterior surface of the wellhead outlet comprises attaching one or more spacing assemblies to the threaded hole. 
         [0019]    Aspect 15: The method according to either of Aspect 13 or Aspect 14, wherein the step of attaching one or more panels to the one or more spacing assemblies comprises attaching one or more panels to the one or more spacing assemblies, wherein the one or more panels is comprised of a flame-retardant ceramic material. 
         [0020]    Aspect 16: The method according to any of Aspects 13-15, wherein the step of attaching one or more panels to the one or more spacing assemblies further comprises fully enclosing the wellhead outlet within the one or more panels, except for any port that extends from the wellhead outlet. 
         [0021]    Aspect 17: The method according to any of Aspects 13-16, wherein the step of attaching one or more panels to the one or more spacing assemblies further comprises including one or more holes in the one or more panels to permit one or more ports that extends from the wellhead outlet to extend through the one or more panels. 
         [0022]    Aspect 18: The method according to Aspect 17, further comprising the step of filling any gap between the one or more ports and a respective one of the one or more holes located in the one or more panels with a flame-retardant ceramic material. 
         [0023]    Aspect 19: The method according to Aspect 18, wherein the step of filling any gap further comprises filling any gap with a thermal blanket. 
         [0024]    Aspect 20: The method according to any of Aspects 13-19, wherein the step of attaching one or more panels to the one or more spacing assemblies comprises attaching one or more panels to the one or more spacing assemblies that are removable from the one or more spacing assemblies. 
         [0025]    Aspect 21: The method according to any of Aspects 13-20, further comprising: removing the one or more panels from the one or more spacing assemblies; and reattaching the one or more panels to the one or more spacing assemblies. 
         [0026]    Aspect 22: A method of protecting a wellhead outlet having at least one gasket, the at least one gasket having a circumference, the wellhead outlet having at least one exterior surface, the method comprising: attaching at least one panel to the at least one exterior surface of the wellhead outlet to form an enclosure around the wellhead outlet, wherein the enclosure provides sufficient insulation for the wellhead outlet in order to prevent the at least one gasket from leaking at a rate in excess of 1 ml/in. per minute of mean measurement of the circumference of the at least one gasket when the wellhead outlet has been pressurized to at least 75% of its rated working pressure with water after the enclosure has been exposed to a continuous flame of at least 1000 degrees F. (538 degrees C.) for at least 30 minutes. 
         [0027]    Aspect 23: The method according to Aspect 22, wherein the step of attaching at least one panel to the at least one exterior surface of the wellhead outlet to form an enclosure around at least a portion of the wellhead outlet further comprises attaching one or more spacing assemblies to the at least one exterior surface of the wellhead outlet and attaching the at least one panel to the one or more spacing assemblies. 
         [0028]    Aspect 24: The method according to either of Aspect 22 or Aspect 23, wherein the step of attaching at least one panel to the at least one exterior surface of the wellhead outlet further comprises attaching least one panel to the at least one exterior surface of the wellhead outlet having at least one non-planar surface. 
         [0029]    Aspect 25: A system comprising: a wellhead outlet having at least one exterior surface; and at least one flame-retardant panel that is directly attached to the at least one exterior surface of the wellhead outlet. 
         [0030]    Aspect 26: The system according to Aspect 25, wherein the at least one flame-retardant panel is in contact with the at least one exterior surface of the wellhead outlet. 
         [0031]    Aspect 27: The system according to either of Aspect 25 or Aspect 26, wherein the at least one flame-retardant panel is removably attached to the at least one exterior surface of the wellhead outlet. 
         [0032]    Aspect 28: The system according to any of Aspects 25-27, wherein the at least one flame-retardant panel has at least one non-planar surface. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0033]    The foregoing summary, as well as the following detailed description of the invention, will be better understood when read in conjunction with the appended drawings. For the purpose of illustrating the invention disclosed herein, certain embodiments in accordance with the herein disclosed invention are shown in the drawings. It should be understood, however, that the herein disclosed invention is not limited to the precise arrangements shown. It should also be understood that, in the drawings, the parts are not necessarily drawn to scale. The present invention will hereinafter be described in conjunction with the appended drawing figures, wherein like numerals denote like elements. In the drawings: 
           [0034]      FIG. 1  is a top perspective view of an exemplary wellhead outlet according to the prior art; 
           [0035]      FIGS. 2A and 2B  are perspective views of an exemplary wellhead outlet according to the prior art, partially outfitted with a fire-resistant enclosure according to the present invention; 
           [0036]      FIGS. 3A and 3B  are perspective views of an exemplary wellhead outlet according to the prior art, fully outfitted with a fire-resistant enclosure according to the present invention; 
           [0037]      FIG. 4  is an exploded view thereof; 
           [0038]      FIG. 5  is a perspective view of an exemplary wellhead outlet according to the prior art, fully outfitted with a fire-resistant partial enclosure according to the present invention; 
           [0039]      FIG. 6  shows a spacing assembly according to the present invention; 
           [0040]      FIG. 7  shows the connection means between an exemplary panel according to the present invention and a prior art wellhead outlet; 
           [0041]      FIG. 8  shows the connection means between exemplary panels according to the present invention; and 
           [0042]      FIG. 9  shows a portion of a wellhead outlet that has been modified to accommodate installation thereto of a fire-resistant structure according to the present invention. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0043]    The ensuing detailed description provides preferred exemplary embodiments only, and is not intended to limit the scope, applicability, or configuration of the herein disclosed inventions. Rather, the ensuing detailed description of the preferred exemplary embodiments will provide those skilled in the art with an enabling description for implementing the preferred exemplary embodiments in accordance with the herein disclosed invention. It should be understood that various changes may be made in the function and arrangement of elements without departing from the spirit and scope of the invention, as set forth in the appended claims. 
         [0044]    To aid in describing the invention, directional terms may be used in the specification and claims to describe portions of the present invention (e.g., upper, lower, left, right, etc.). These directional definitions are merely intended to assist in describing and claiming the invention and are not intended to limit the invention in any way. In addition, reference numerals that are introduced in the specification in association with a drawing figure may be repeated in one or more subsequent figures without additional description in the specification in order to provide context for other features. 
         [0045]    Referring generally to  FIGS. 1-9 , embodiments of a system for protecting a wellhead outlet  1  according to the prior art will be described in detail.  FIG. 1  is a perspective view of an exemplary wellhead outlet  1  according to the prior art. The wellhead outlet  1  comprises a high pressure bowl  2  having a body  4  and a lid  3 . Extending from one side of the body  4  of the wellhead outlet  1  is a high pressure data port  14 . Connected to another side of the body  4  of the wellhead outlet  1  is a low pressure bowl  9 . The low pressure bowl  9  comprises a body  10  having an exterior surface  11  and an exposed end  12  having an exterior surface  13 . An atmosphere data port  15  extends from the body  10  of the low pressure bowl  9 . Although one embodiment of a wellhead outlet  1  is shown and described in this application, it should be understood that the herein disclosed systems and methods for protecting a wellhead outlet are applicable, mutatis mutandis, to a wellhead outlet of any configuration, and that the particular embodiment of a wellhead outlet  1  shown in the appended figures and described herein is presented only for discussion purposes. 
         [0046]    The herein disclosed systems and methods, in one respect, describe enclosures or partial enclosures (see, e.g., enclosure  30  of  FIGS. 3A and 3B  and partial enclosure  130  of  FIG. 5 ) for protecting the wellhead outlet  1  from fires. In one embodiment, this is accomplished by spacing one or more flame-retardant or protective panels away from exterior surface(s) of the wellhead outlet  1 . These protective panels can be retrofitted to enclose or partially-enclose existing wellhead outlets, or new wellhead outlets could be provided that have pre-existing means to attach the protective panels thereto. Protective panels can be removed from a wellhead outlet to permit the wellhead outlet to be serviced or to allow the protective panels to be reused, for example after a well has run dry or been abandoned. Wellhead outlets may also be protected from flames by applying flame-retardant coatings, films, or other materials directly to the parts of the wellhead outlet. 
         [0047]    As shown in  FIGS. 2A and 2B , the enclosure  30  is constructed by first attaching one or more spacing assemblies  32   a - 32   f  to the exterior surface(s) of one or more parts of the wellhead outlet  1 . In this embodiment of the enclosure  30 , six spacing assemblies  32   a - 32   f  are used, although one of ordinary skill in the art would recognize that a lesser or greater quantity of spacing assemblies can be used based on such factors as the size, dimensions, and geometry of the wellhead outlet to which the spacing assemblies are being attached and the weight and geometry of the protective panels that are being attached to the spacing assemblies. In this embodiment, the spacing assemblies  32   a - 32   f  are attached via removable hardware (i.e., bolts), so that the spacing assemblies  32   a - 32   f  can be removed from the wellhead outlet  1 . In alternate embodiments, the spacing assemblies  32   a - 32   f  could be attached to the exterior surface(s) of one or more parts of the wellhead outlet  1  in other ways, for example by riveting, bonding, or through use of a suitable adhesive. 
         [0048]    In the embodiment shown in  FIGS. 2A and 2B , spacing assembly  32   a  is attached to the exterior surface  11  of the exposed end  12  of the body  10  of the low pressure bowl  9 , spacing assemblies  32   b - 32   d  are attached to the exterior surface  6  of the bottom side  5  of the body  4  of the high pressure bowl  2 , and spacing assemblies  32   e , 32   f  are attached to the exterior surface  8  of the rear side  7  of the body  4  of the high pressure bowl  2 . The spacing assemblies  32   a - 32   f  thus provide spacing away from the various exterior surfaces of the wellhead outlet  1  in all three primary axes. In alternate embodiments, the panels described below may be located directly adjacent to the exterior surface(s) of the wellhead outlet to which it is attached. 
         [0049]      FIGS. 3A-4  show an enclosure  30  comprising a plurality of panels, each of which is connected either directly to one or more of the spacing assemblies  32   a - 32   f  or indirectly to one or more of the spacing assemblies  32   a - 32   f  via one or more additional panels. In this embodiment, the panels are removably attached to the spacing assemblies  32   a - 32   f , so that after installation the panels can be removed from and reattached to the spacing assemblies  32   a - 32   f . In this embodiment, the enclosure  30  comprises a top panel  42 , a side panel  44  that is directly connected to spacing assembly  32   a , front panels  48 , 49 , 50 , a bottom panel  55  that is directly connected to spacing assemblies  32   b - 32   d , and a rear panel  53  that is directly connected to spacing assemblies  32   e , 32   f . In  FIGS. 3A and 3B  (as well as  FIGS. 7 and 8 ), the panels of the enclosure  30  are rendered transparent so that the connections between parts located behind the panels, as well as the placement of the wellhead outlet  1  and its parts respective to the panels of the enclosure  30 , can be clearly seen. It should be understood that, in many embodiments, the panels will not actually be transparent. In  FIGS. 3A, 3B, and 7 , the lines representing the wellhead outlet  1  are given a lighter weight than that of the lines representing the parts of the enclosure  30 . 
         [0050]    In this embodiment, the panels are a fiber-reinforced composite comprised of a matrix of SiOC (silicon oxycarbide) embedded with Nextel™ fibers produced by 3M Company of St. Paul, Minn., U.S.A. In alternate embodiments, the matrix may be any suitable ceramic material or high-temperature polymer, and the fibers may be carbon fiber, glass fiber, boron nitride fiber, or other suitable fibers. 
         [0051]    In this embodiment, top panel  42  has an exterior surface  42   a  and a port hole  43  that permits passage of the atmosphere data port  15  of the wellhead outlet  1  therethrough. Front panel  50  has an exterior surface  50   a  and a port hole  51  that permits passage of the high pressure data port  14  of the wellhead outlet  1  therethrough. Side panel  44  has an exterior surface  44   a , front panel  48  has an exterior surface  48   a , front panel  49  has an exterior surface  49   a , side panel  46  has an exterior surface  46   a , rear panel  53  has an exterior surface  53   a , and bottom panel  55  has an exterior surface  55   a . In this embodiment, each of the exterior surfaces  42   a , 44   a , 46   a , 48   a , 49   a , 50   a , 53   a , 55   a  of the respective panels  42 , 44 , 46 , 48 , 49 , 50 , 53 , 55  is planar. In alternate embodiments, at least a portion of the exterior surface of at least one panel of the enclosure is planar. In further alternate embodiments according to the present invention, the panels of the enclosure may include no planar portions. 
         [0052]      FIG. 6  depicts the parts of one of the spacing assemblies (i.e., spacing assemblies  32   a - 32   f ). Each of the spacing assemblies  32   a - 32   f  comprises a spacing fastener  33  (which in this embodiment is a bolt), the spacing fastener  33  having a head  34  and a shaft  35 , an exterior washer  36 , an interior washer  38 , and spacing blocks  40   a - 40   c . The spacing blocks  40   a - 40   c  are placed adjacent the exterior surface of the wellhead outlet  1  and the interior washer  38  is placed adjacent the spacing blocks  40   a - 40   c . In this embodiment three spacing blocks  40   a - 40   c  are used, and each spacing block  40   a - 40   c  is tubiform in shape. In alternate embodiments, a greater or lesser number of spacing blocks may be used, and/or the spacing blocks  40   a - 40   c  may have a different shape. In this embodiment, the spacing blocks  40   a - 40   c  are made of the same fiber-reinforced composite material as the panels. In alternate embodiments, the spacing blocks  40   a - 40   c  may be comprised of any suitable insulative material. In alternate embodiments, the spacing fastener may comprise some part other than a bolt, for example a lag, screw, rod, pipe, or tube that is connectable to both the wellhead outlet  1  and the enclosure  30 . 
         [0053]    In this embodiment, the interior washer  38  is located adjacent to the interior surface of the respective panel. The exterior washer  36  is located around the shaft  35  of the spacing fastener  33  and adjacent the exterior surface of the respective panel, and the shaft  35  of the spacing fastener  33  is passed through a spacing hole located in the respective panel, the interior washer  38 , and the spacing blocks  40   a - 40   c  and then connected to the wellhead outlet. The head  34  of the spacing fastener  33  and the exterior washer  36  collectively form the exterior portion  39  of the spacing assembly, which is located external to the enclosure  30  (i.e., external to the respective panel). The spacing blocks  40   a - 40   c  and the interior washer collectively form the interior portion  37  of the spacing assembly, which is located internal to the enclosure  30  (i.e., internal to the respective panel). A portion of the shaft  35  of the spacing fastener  33  is located within the spacing fastener hole in the respective panel.  FIG. 7  shows the connection of the side panel  44  to the exterior surface  13  of the exposed end  12  of the body  10  of the low pressure bowl  9  of the wellhead outlet  1  via the spacing assembly  32   a.    
         [0054]    As best seen in  FIG. 4 , rear panel  53  includes spacing fastener hole  54   a  and spacing fastener hole  54   b , which accommodate, respectively, spacing assembly  32   f  and spacing assembly  32   e ; bottom panel  55  includes spacing fastener holes  56   a - 56   c , which accommodate, respectively, spacing assemblies  32   b - 32   d ; and side panel  44  includes spacing fastener hole  45 , which accommodates spacing assembly  32   a . As noted previously, the side panel  44  is directly connected to the wellhead outlet  1  via spacing assembly  32   a , the bottom panel  55  is directly connected to the wellhead outlet  1  via spacing assemblies  32   b - 32   d , and the rear panel  53  is directly connected to the wellhead outlet via spacing assemblies  32   e , 32   f . These panels  44 , 53 , 55  are then connected to the additional panels  42 , 46 , 48 , 49 , 50  via spacing blocks and panel attachment fasteners to form the enclosure  30 . All of the spacing blocks and panel attachment fasteners of the enclosure  30  are shown in the exploded view of  FIG. 4 , but for purposes of readability these parts are not labeled and all explode lines are not included. 
         [0055]      FIG. 8  shows an exemplary corner of the enclosure  30 , where top panel  42 , side panel  44 , and front panel  48  are joined together via a panel attachment block  60 . In this embodiment, the block  60  is cubic in shape and has internal threading located through the center of all three major axes thereof, with the internal threading terminating at three adjacent faces of the block  60  at fastener holes  61   a - 61   c  (fastener hole  61   c  labeled in  FIG. 3A ). Exterior washer  63   a  is placed around panel attachment fastener  62   a , which is used to secure top panel  42  to the fastener hole  61   a  of block  60 ; exterior washer  63   b  is placed around panel attachment fastener  62   b , which is used to secure side panel  44  to the fastener hole  61   b  of block  60 ; and exterior washer  63   c  is placed around panel attachment fastener  62   c , which is used to secure front panel  48  to the fastener hole  61   c  of block  60 . In alternate embodiments, the panels may be directly connected together without the use of corner blocks. 
         [0056]    In some embodiments, as shown in  FIG. 9 , one or more exterior surfaces of a prior art wellhead outlet  1  may be tapped so that these surfaces are outfitted with internally threaded holes  70  for accommodation of the shaft  35  of the spacing fastener  33  therein. In alternate embodiments according to the present invention, the wellhead outlet may be provided with tapped holes already located in the exterior surface(s) thereof for accommodating the spacing fastener(s), and the wellhead outlet provided along with the necessary parts of the enclosure as part of the protective system for the wellhead outlet. 
         [0057]    The embodiment of the enclosure  30  shown in  FIGS. 3A-4  fully encloses the wellhead outlet  1  therein, with the exception of the port holes  43 , 51  that permit the atmosphere data port  15  and high pressure data port  14 , respectively, to pass therethrough and exit the enclosure  30 . In embodiments where there is a gap left between one or both of the port holes  43 , 51  and the respective port  14 , 15 , said gap is preferably filled with a flame-retardant material, for example a commercially-available fire blanket. One example of a suitable, commercially-available fire blanket is the Fiberfrax S Durablanket which is produced by Thermal Products Company, Inc. of Norcross, Ga., U.S.A. 
         [0058]    In some applications, it may not be necessary to fully enclose all sides of the wellhead outlet  1  within an enclosure.  FIG. 5  shows a partial enclosure  130  for a wellhead outlet that utilizes only some of the parts of the full enclosure  30 . For example, in this embodiment the partial enclosure  130  utilizes only the side  46 , rear  53 , and bottom  55  panels, spacing assemblies  32   b - 32   f  (spacing assemblies  32   d - 32   f  not shown in  FIG. 5 ), and some panel attachment blocks and accompanying panel attachment fasteners. 
         [0059]    One purpose of the enclosure  30  or partial enclosure  130  is that it is designed to enable the wellhead outlet  1  to withstand exposure to fire or other sources of high heat without seal failure. The enclosure  30  is designed to protect the seals of the wellhead outlet  1 —e.g., the high pressure bowl  2  and the fiber optic feedthrough assembly (not labeled), which is located interior to the low pressure bowl  9 —from significant leakage after exposure to fire. 
         [0060]    In order to demonstrate this capability, the wellhead outlet  1  (i.e., the end connection) was fitted with the enclosure  30  and successfully tested using the following test protocol:
       An exterior surface of the enclosure  30  is fitted with at least three thermocouples, each thermocouple being located within the center of 1.5-inch (3.8 cm) cubic carbon steel calorimeter blocks, the thermocouples and calorimeter blocks being spaced apart from each other within the plane of the exterior surface of the enclosure  30  by no more than 12 inches (30.5 cm);   The wellhead outlet system is completely filled with water;   The wellhead outlet system is pressurized to at least 75% of its rated working pressure (for example, if an end connection is rated at 2000 psig (13.8 MPa), the system should be pressurized to at least 1500 psig (10.3 MPa));   A fire is established in the vicinity of the end connection to be tested (i.e., the exterior surface of the enclosure) and the flame temperature is monitored during the “burn period,” which is no less than 30 minutes in duration from the time that the fire is first established:
           The average temperature reading of the thermocouples must reach 1400 degrees F. (761 degrees C.) within 2 minutes from the time that the fire is established;   The average temperature reading of the thermocouples must be maintained between 1400 and 1800 degrees F. (761 and 980 degrees C.), with no reading less than 1300 degrees F. (704 degrees C.), until the average calorimeter temperature reaches 1200 degrees F. (650 degrees C.). The average calorimeter temperature shall reach 1200 degrees F. (650 degrees C.) within 15 minutes from the time that the fire is established. After those average calorimeter temperatures are reached, for the remainder of the duration of the burn period, the calorimeters shall maintain a minimum average temperature of 1200 degrees F. (650 degrees C.), and no calorimeter reading shall be below 1050 degrees F. (565 degrees C.);   
           The wellhead outlet system is then cooled to no more than 212 degrees F. (100 degrees C.), and the system is depressurized;   The pressure in the wellhead outlet system is then increased to no less than 75% of its rated working pressure, and this test pressure is held for a minimum of 5 minutes;   The water leakage rate from the end connection is measured during the burn and cooldown periods and during the 5 minute period after depressurization and repressurization, with a “pass” result for this test being an end connection leakage rate of no greater than 1 ml/in. per minute of mean primary gasket circumference (i.e., the mean circumference of the primary gasket of the tested end connection).       
 
         [0070]    It should be appreciated that the foregoing is presented by way of illustration only, and not by way of any limitation, and that various alternatives and modifications may be made to the illustrated embodiments without departing from the spirit and scope of the present invention.