Patent Document

CROSS-REFERENCE TO RELATED APPLICATION  
       [0001]     This application claims the benefit of copending U.S. Provisional application Ser. No. 60/559,177, filed on Apr. 2, 2004. 
     
    
     BACKGROUND OF THE INVENTION  
       [0002]     1. Field of the Invention  
         [0003]     The present invention relates generally to devices which are placed in a pipeline, in-line, to stop the flow of fluid through the pipeline.  
         [0004]     2. Description of the Related Art  
         [0005]     In the process of removing oil or other related products from a source well, particularly in cold (adverse) environments such as Alaska, USA, it is known to inject materials under high pressure into the well in order to assist in the product removal effort. It is further known to inject differing materials in alternating fashion. Often these differing materials are incompatible, particularly in such adverse temperature environments. These materials are commonly delivered to the well through separate pipelines which come together at the well. In order to alternately provide such incompatible materials to the well as required, it is necessary to halt the flow of one material so as to allow the flow of the other, or vice versa. A need, therefore, exists for a device which prevents the flow of a material through a pipeline which can in the alternative allow such flow as required. It is a particular need for such a device for use in high pressure applications and/or in adverse environments.  
         [0006]     Valves of many different configurations, such as gate valves or pin valves or the like have been commonly used in an effort to satisfy the above-described requirement. However, known valves include some type of mechanism which closes, or seats, to prevent flow which can be moved, or positioned, to alternately allow flow. Such repeated positioning between the valve and the seat causes wear over time. Eventually such valves begin to leak, particularly in high pressure, adverse conditions which could cause a serious problem in the above-described environment. A need, therefore, exists for a device which may alternately restrict flow and allow flow without causing wear to the sealing mechanism.  
         [0007]     An additional limitation of valves commonly available is that they include a valve seat such that when, and if a leak occurs, the valve will allow fluid to enter the pipeline. In an effort to prevent this problem, it is common to install multiple of such valves employed in series. However, if one leaks, it vents fluid to the next valve in the pipeline. Over time, if the next valve begins to leak, fluid again enters the pipeline. A need exists for a device which includes multiple sealing surfaces wherein if one were to leak, fluid would not vent to the next sealing surface or the pipeline.  
       SUMMARY OF THE INVENTION  
       [0008]     The present invention comprises a double block isolation chamber suited for use where it is necessary to be able to block a pipeline in an effort to prevent flow of its contents. Particularly, the isolation chamber of the present invention provides a separate seal block wedge positioned at both the inlet and the outlet of the chamber, herein referred to as “double block”. The present invention is particularly suitable for situations where it is desired to be able to alternately block the flow-through the pipeline, allow fluid to flow-through the pipeline, and/or meter the flow of fluid through the pipeline.  
         [0009]     The present invention is suited for use in high pressure (between approx. 2500 and 6500 psig) pipelines (i.e., 2 in. or 3 in. schedule  160  pipeline) in adverse environments. Such adverse environments include extremely cold operating conditions such as less than 0° and commonly −50° F., or even colder. The contents of the pipeline could be any fluid, including, but not limited to, water (salt water), natural gas (or the like), or petroleum (or the like).  
         [0010]     The three-wedge double block isolation chamber of the present invention includes a body with an internal chamber bounded by an inlet at a first end, an outlet at a second end, and a wedge assembly positioned in the chamber. The wedge assembly may be either a blind wedge assembly, flow-through wedge assembly or a meter wedge assembly. The wedge assembly includes, in its basic embodiment, three elements: an upstream wedge, a downstream wedge, and a force wedge. Since there is no movement between the wedges, the seals will not wear over time.  
         [0011]     The wedges seat into the internal chamber of the body such that the force wedge is positioned between the upstream wedge and the downstream wedge so as to create a seal between the upstream wedge and the inlet and the downstream wedge and the outlet. The force wedge includes an upstream surface and a downstream surface. Either or both of the upstream surface and/or the downstream surface of the force wedge may include a taper thereon.  
         [0012]     The upstream surface of the upstream wedge is substantially flat and is pressed against the inlet of the body. The upstream surface of the upstream wedge includes a seal to create an interface (seal) between the upstream surface and the inlet. The downstream surface of the upstream wedge may include a taper thereon which mates an opposing taper on the upstream face of the force wedge.  
         [0013]     The downstream surface of the downstream wedge is substantially flat and pressed against the outlet of the body. The downstream surface of the downstream wedge includes a seal to create a seal between the downstream surface and the outlet. The upstream surface of the downstream wedge may include a taper thereon which mates an opposing taper on the downstream face on the force wedge.  
         [0014]     The tapered interface surfaces between the upstream wedge, downstream wedge, and force wedge act to force the upstream wedge and the downstream wedge against the inlet and outlet respectively. A substantial outward force is achieved to produce a seal at both the inlet end of the chamber and the outlet end of the chamber. The force wedge is retained in position by a force rod positioned against a top cover. The top cover is bolted to the body to securely hold the wedge assembly in place.  
         [0015]     The wedge assembly of the present invention includes an interchangeable blind assembly, a flow-through assembly, and/or a meter wedge assembly. The blind assembly blocks the flow of liquid through the chamber and includes an upstream blind wedge, a downstream blind wedge, and a force blind wedge. The seals created at the inlet and the outlet create a double blind isolation chamber between the inlet and the outlet.  
         [0016]     The flow of liquid through the isolation chamber is blocked when the blind assembly is secured into the body. Flow is resumed when the line is depressurized and the blind wedge assembly replaced with a flow-through wedge assembly. The blind wedge assembly is removed by removing the top cover. The flow-through wedge assembly is then inserted which includes flow-through wedges that each include a central hole which is substantially the same diameter as the I.D. of the pipeline.  
         [0017]     Features of the present invention include a three-wedge assembly positioned in a chamber, the design and shape of the three-wedge assembly and particularly the fact that the assembly creates a seal (double block) at both the inlet and the outlet of the isolation chamber in order to substantially prevent pipeline fluids from passing from the inlet through the outlet or vice-versa when the blind wedge assembly is installed in the body. Therefore, an isolation chamber which double blocks and seals is described. In the event that either the inlet seal or the outlet seal were to leak, pipeline fluid would enter the isolation chamber, however, the other, second seal would assist to prevent the fluid from entering the pipeline. The fluid would then be retained either within the isolation chamber or, depending upon the volume, leak outside the body to the surrounding atmosphere rather than into the pipeline.  
         [0018]     It is, therefore, an object of the present invention to provide an isolation chamber for use in a pipeline which is capable of sealing the flow of liquid past the isolation chamber. It is another object of the present invention to provide such an isolation chamber which provides a seal at both the inlet and the outlet of the isolation chamber (double block).  
         [0019]     Another object of the present invention is to provide a double block blind isolation chamber for use in high pressure adverse environments.  
         [0020]     An additional object of the present invention is to provide a double block isolation chamber which is designed to leak to atmosphere rather than into the pipeline.  
         [0021]     It is an additional object of the present invention to provide such a double block isolation chamber which is simple in design and easy to operate and maintain.  
         [0022]     It is a further object of the present invention to provide such a double block isolation chamber including a wedge assembly which is easily accessible for removal/replacement.  
         [0023]     It is yet a further object of the present invention to provide such a double block isolation chamber which includes a blind wedge assembly having an upstream wedge, a downstream wedge, and a force wedge, each having mated tapered surfaces.  
         [0024]     It is still an additional object of the present invention to provide such a double block isolation chamber wherein the blind wedge assembly can be easily replaced with a flow-through wedge assembly having an upstream flow-through wedge, a downstream flow-through wedge, and a force flow-through wedge.  
         [0025]     Thus, the present invention is well adapted to carry out the objects and attain the ends and advantages mentioned above as well as those inherent therein. While certain objects have been described, it is understood that additional objects and features may exist and become apparent from the specification, the claims, and/or the figures.  
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0026]      FIG. 1  is an exploded view of the three-wedge double block isolation chamber of the present invention depicting the flow-through wedge assembly.  
         [0027]      FIG. 2  is the blind wedge assembly of the three-wedge double block isolation chamber of the present invention.  
         [0028]      FIG. 3  is the body of the three-wedge double block isolation chamber of the present invention.  
         [0029]      FIG. 4  is a top view of the three-wedge double block isolation chamber of the present invention with the wedge assembly removed.  
         [0030]      FIG. 5  is view taken along line A-A of the  FIG. 4 .  
         [0031]      FIG. 6  is view taken along line B-B of  FIG. 4 .  
         [0032]      FIG. 7  is an alternate embodiment view taken along line B-B of  FIG. 4 .  
         [0033]      FIG. 8  is an end view of the inlet flange of the three-wedge double block isolation chamber of the present invention.  
         [0034]      FIG. 9  is a top detail of the compression bar of the blind wedge assembly of the three-wedge double block isolation chamber of the present invention.  
         [0035]      FIG. 10  is a side view of the compression bar of  FIG. 9 .  
         [0036]      FIG. 11  is an isometric view of the blind wedge of the blind wedge assembly.  
         [0037]      FIG. 12  is a front view of the blind wedge of the blind wedge assembly.  
         [0038]      FIG. 13  is a side view of the blind wedge of  FIG. 11 .  
         [0039]      FIG. 14  is a front view of the blind force wedge of the blind wedge assembly.  
         [0040]      FIG. 15  is a side view of the blind force wedge of  FIG. 14 .  
         [0041]      FIG. 16  is a top view of the cover for the body of the flow-through wedge assembly.  
         [0042]      FIG. 17  is a side view of the cover of  FIG. 16 .  
         [0043]      FIG. 18  is an isometric view of the flow-through wedge of the flow-through wedge assembly.  
         [0044]      FIG. 19  is a front view of the flow-through wedge of  FIG. 18 .  
         [0045]      FIG. 20  is a side view of the flow-through wedge of  FIG. 18 .  
         [0046]      FIG. 21  is a front view of the flow-through force wedge of the flow-through wedge assembly.  
         [0047]      FIG. 22  is a side view of the flow-through force wedge of  FIG. 21 .  
         [0048]      FIG. 23  is a top view of the flow-through force wedge of  FIG. 21 .  
         [0049]      FIG. 24  is a top view of the cover seal.  
         [0050]      FIG. 25  is a view of the cover seal of the  FIG. 24  taken along line A-A.  
         [0051]      FIG. 26  is a top view of the spring seal.  
         [0052]      FIG. 27  is a view of the spring seal of  FIG. 26  taken along line A-A.  
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0053]     Before explaining the present invention in detail, it is important to understand that the invention is not limited in its application to the details of the apparatus illustrated and described herein. The invention is capable of other embodiments and of being practiced or carried out in a variety of ways. It is to be understood that the phraseology and terminology that is employed herein is the for the purpose of description and not of limitation.  
         [0054]     Referring now to the drawings wherein like reference numerals indicate the same parts or steps throughout the several views.  FIG. 1  shows an exploded view of the three-wedge double block isolation chamber  100  of the present invention.  FIG. 1  depicts the isolation chamber  100  with flow-through wedge assembly  102  therein.  FIG. 2  depicts an alternate blind wedge assembly  104 .  
         [0055]     The three-wedge double block isolation chamber  100  includes a body  108  with chamber  109  therein. Chamber  109  is sized and configured to receive a wedge assembly such as flow-through wedge assembly  102  or blind wedge assembly  104  as required. A cover such as cover  2  (or cover  12 ) can be secured to body  108  to retain wedge assembly  102  (or  104 ) within chamber  109 .  
         [0056]     An inlet flange  106  and an outlet flange  110  are secured to body  108  to allow three-wedge double block isolation chamber  100  to be installed in a pipeline. Inlet flange  106  and outlet flange  110  are bolted to opposing pipeline flanges through bolt holes  113  and  113 ′ respectively. Inlet flange  106  and outlet flange  110  retain the pipeline in substantial alignment even when the wedge assemblies are removed from body  108 . Inlet flange  106  includes an inlet orifice  107  to allow fluid to enter body  108  so that the pipeline is in fluid communication with chamber  109 .  
         [0057]      FIG. 3  depicts body  108  from a side view to which inlet flange  106  and outlet flange  110  are secured.  FIG. 4  depicts body  108  from a top view with cover  2  and flow-through wedge assembly  102  removed. The top surface  115  of body  108  is substantially flat to receive top cover  2  (or  12 ). A plurality of holes, collectively  114 , are drilled and tapped into top surface  115  of body  108  in order to receive a plurality of bolts, collectively  10  ( FIG. 1 ), for the purpose of securing cover  2  onto top surface  115  of body  108 . With cover  2  (or  12 ) removed, chamber  109  is open and extends into body  108 . A groove  116  may be cut into top surface  115  of body  108  for the purpose of receiving a seal  9  ( FIG. 1 ) which substantially encircles chamber  109 .  
         [0058]     Referring next to  FIG. 5 , a cutaway view of body  108  with inlet flange  106  and outlet flange  110  secured thereon. In the preferred embodiment, inlet flange  106  and outlet flange  110  are molded integrally with body  108 . As shown in  FIG. 5 , inlet orifice  107  of inlet flange  106  extends into chamber  109  through inlet  120  such that chamber  109  is in fluid communication with the pipeline to which inlet flange  106  is attached. Also, as shown, outlet orifice  111  extends from an outlet  122  in chamber  109  through body  108  and outlet flange  110 . In this way, chamber  109  is in fluid communication with the pipeline to which outlet flange  110  is secured. A drain  124  may be drilled through body  108  into chamber  109  to allow any fluid which may be present in chamber  109  to be released to atmosphere. Drain  124  may be fitted with a valve or a pressure release valve as required to seal chamber  109  during flow-through or metering operation. When blind wedge assembly  104  is installed in chamber  109 , drain  124  may be opened so as to provide an escape for any fluid which may leak into chamber  109 .  
         [0059]      FIG. 6  is a cross-sectional view depicting chamber  109  of body  108 . In the preferred embodiment, chamber  109  includes a squared-bottom surface  126 .  FIG. 7  depicts an alternate embodiment where chamber  109  includes a radius-bottom surface  128 . The bottom surface of chamber  109  may be squared as in the preferred embodiment of  FIG. 6  for ease of manufacture or may alternately be radiused as in  128  of  FIG. 7  so as to match the radius of the wedge assembly inserted therein.  
         [0060]      FIG. 8  depicts inlet flange  106  from an end view, including bolt holes  113 , inlet orifice  107 , and inlet face  117 . Inlet face  117  provides a sealing surface with a pipeline flange bolted thereto. Outlet flange  110  includes an outlet orifice  111  to allow fluid to exit body  108  so that chamber  109  is in fluid communication with the pipeline. An outlet face  118  provides a sealing surface with an outlet pipeline flange bolted thereto. Thus, the three-wedge double block isolation chamber may be instilled in-line on a pipeline.  
         [0061]     Referring back to  FIG. 1 , wedge assembly  102  is inserted into chamber  109  of body  108 . In the embodiment of  FIG. 1 , isolation chamber  100  is depicted with a flow-through wedge assembly  102  positioned therein. In its preferred embodiment, flow-through wedge assembly  102  can be configured in a 2″ or 3″ configuration matching the size of the pipeline into which isolation chamber  100  is installed. However, wedge assembly  102  can be configured to fit any pipeline I.D. as other suitable configurations are contemplated without departing from the spirit and scope of the invention.  
         [0062]     Flow-through wedge assembly  102  includes, generally, a flow-through force wedge  3  positioned between a pair of flow-through wedges  4  and  4 ′, a pair of spring seals  5  and  5 ′, and a cover  2  capable of being secured onto the top  115  of body  108  by a plurality of screws, collectively  10  and washers  11 . Ten such screws  10  and washers  11  are depicted in  FIG. 1  for the purpose of exemplification.  
         [0063]     Referencing  FIG. 1  in combination with  FIGS. 18, 19 , and  20 , an upstream wedge  4  includes a seal  5  installed in channel  134  or upstream surface  135  is inserted into chamber  109  adjacent inlet  120  concentric with inlet orifice  107 . Upstream wedge  4  includes a central orifice  136  of a diameter substantially equal to the diameter of inlet orifice  107  (and the I.D. of the pipeline).  
         [0064]     Downstream wedge  4 ′ is substantially identical to upstream wedge  4  but is inserted into chamber  109  such that seal  5 ′ positioned on downstream surface  139  is adjacent outlet  122 . Downstream wedge  4 ′ including a downstream seal  5 ′ is positioned in chamber  109  adjacent outlet flange  110  concentric with outlet orifice  111  within outlet flange  110 . Both upstream wedge  4  and downstream wedge  4 ′ include a taper on their interior surfaces which mate the taper of flow-through force wedge  3  which is inserted between upstream wedge  4  and downstream wedge  4 ′. Specially, downstream surface of wedge  4  includes a taper which mates the taper on upstream surface  140  of flow-through force wedge  3  and upstream surface of wedge  4 ′ includes a taper which mates the taper on downstream surface  142  of flow-through force wedge  3 . Flow-through force wedge  3  is depicted in  FIGS. 21-23 . In the preferred embodiment, a taper of 3° has been deemed particularly suitable, however, other tapers are contemplated. An orifice  144  in flow-through force wedge  3  is preferably concentric with those in upstream wedge  4  and downstream wedge  4 ′ to allow an unimpeded flow of liquid from inlet passage  107  past inlet  120  through chamber  109  past outlet  122  and out through outlet passage  111 .  
         [0065]     Flow-through force wedge  3  includes holes  146  and  146 ′ to receive dowel pins  6  and  6 ′ (and dowel springs  7  and  7 ′) respectively. Force wedge  3  may also include a hole  148  drilled and tapped therein to receive a bolt extending through cover  2 .  
         [0066]     Flow-through force wedge  3  includes a taper which mates the taper of upstream wedge  4  on its downstream face  137  and downstream wedge  4 ′ on its upstream face  138  such that when flow-through force wedge  3  is pressed firmly in chamber  109  between upstream flow-through wedge  4  and downstream flow-through  4 ′ a seal is obtained between seal  5  and inlet  120  inside chamber  109  and seal  5 ′ in outlet  122  inside chamber  109 .  
         [0067]     A pair of dowel pins  6  and  6 ′ which each include a dowel spring  7  and  7 ′ surrounding dowel pins  6  and  6 ′ respectively are positioned in holes  146  and  146 ′ in flow-through force wedge  3  between flow-through force wedge  3  and cover  2  when flow-through valve  102  is inserted into chamber  109 . Dowel pins  6  and  6 ′ force and retain flow-through force wedge  3  between upstream  4  and downstream wedge  4 ′ such that the holes in upstream wedge  4 , flow-through force wedge  3 , and downstream wedge  4 ′ remain concentric. The upper surface of body  108  may include locator pins  8  and  8 ′ thereon for accurately locating cover  2  onto body  108 .  
         [0068]     A seal  9  may be positioned between cover  2  and body  108 . Seal  9  is shown in detail in  FIGS. 23 and 25  and is preferably constructed of an elastomeric material and available commercially. Seal  9  is positioned in channel  114  ( FIGS. 1, 4 , and  5 ).  
         [0069]      FIGS. 16 and 17  depict cover  2  which retains flow-through wedge assembly  102  within chamber  109 . Cover  2  includes a plurality of bolt holes, collectively  130 , drilled therethrough to receive bolts  10  of  FIG. 1 . Cover  2  also includes holes  132  and  132 ′ drilled partially therethrough to receive locator pins  8  and  8 ′ respectively. Referring back to  FIG. 1 , bolts  10  and washers  11  are inserted to retain cover  2  onto body  108  so as to provide an upper surface which forces dowel pins  6  and  6 ′ and thereby flow-through force wedge  3  into concentric arrangement with upstream flow-through wedge  4  and downstream flow-through wedge  4 ′ as described above.  
         [0070]     Three-wedge double block isolation chamber  100  of the present invention also includes a blind wedge assembly  104  ( FIG. 2 ) which is interchangeable with flow-through valve assembly  102  ( FIG. 1 ) when it is desirous to prevent the flow of fluid through the pipeline and specifically through isolation chamber  109 . Blind wedge assembly  104  includes, generally, blind force wedge  13 , upstream blind wedge  14 , downstream blind wedge  14 ′, compression bar  12  and force bolt  15 . When interchanged with flow-through wedge  102 , blind wedge  104  is inserted into chamber  109  of body  108  such that blind force wedge  13  is positioned between upstream block wedge  14  and downstream blind wedge  14 ′.  
         [0071]     Upstream blind wedge  14  is depicted in  FIGS. 11-13  and includes a channel  150  to receive seal  16  ( FIG. 2 ) therein. Seal  16  is the same type of seal as seal  5  depicted in  FIGS. 26 and 27  and described above with regard to flow-through wedge assembly  102 . Upstream block wedge is solid to prevent the flow of fluid. Upstream blind wedge  14  is positioned in chamber  109  such that upstream surface  152  including seal  16  is adjacent inlet  120  such that upstream blind wedge  14  blocks the flow of liquid from entering chamber  109  through inlet  120 . Likewise, downstream blind wedge  14 ′ is positioned in chamber  109  adjacent outlet  122  and includes a seal  16 ′ so as to block the flow of liquid to/from outlet  122 . Downstream blind wedge  14 ′ is substantially identical to upstream wedge  14  but is inserted into chamber  109  such that seal  16 ′ is positioned against outlet  122 .  
         [0072]     Blind force wedge  13  is shown in  FIGS. 14 and 15 . Blind force wedge  13  is positioned between upstream blind wedge  14  and downstream blind wedge  14 ′ and provides pressure to upstream blind wedge  14  and downstream blind wedge  14 ′ to retain a tight seal between inlet  120  and outlet  122 , respectively, thereby effectively blocking the flow of liquid through isolation chamber  100 .  
         [0073]     Both upstream blind wedge  14  and downstream blind wedge  14 ′ include a tapered surface which mates a taper on the faces of blind force wedge  13 . Specifically, downstream surface of block wedge  14  includes a taper which mates the taper on upstream surface  160  of blind force wedge  13 , and upstream surface of wedge  14 ′ includes a taper which mates the taper on downstream surface  162  of blind force wedge  13 . A taper of 3° has been found particularly suitable for the preferred embodiment, however, other suitable tapers are contemplated.  
         [0074]     Blind wedge assembly  104  is secured in chamber  109  by compression bar  12 . Compression bar  12  is shown in greater detail in  FIGS. 9 and 10 . Compression bar  12  includes a plurality of holes  164  drilled therethrough to receive bolts and washers (such as bolts  10  and washers  11  of  FIG. 1 ) which are screwed into holes  114  of body  108 . Compression bar  12  also includes holes  166  and  166 ′ to receive locator pins  8  and  8 ′ of body  108 . A central hole  168  is drilled and tapped in compression bar  12  to receive a force rod  15  ( FIG. 2 ).  
         [0075]     As can be seen in  FIGS. 9 and 10 , a cutout  170  and  170 ′ on each side of compression bar  12 . In addition, compression bar  12  includes an arched portion  172  therein. The purpose of cutouts  170  and  170 ′ and arched portion  172  is so that compression bar  12  does not seal against body  108 . Since chamber  109  is not sealed, in the event that upstream block wedge  14  or downstream bock wedge  14 ′ were to leak, fluid would enter chamber  109  and exit around compression bar  12  into the atmosphere rather than through the other seal. As a result, fluid would not leak past the secured seal.  
         [0076]     Upon assembly, blind wedge assembly  104  is inserted into chamber  109  of body  108  such that compression bar  12  is secured to the top of body  108  using bolts  10  and washers  11 . Force rod  15  is threaded through compression bar  12  to force blind force wedge  13  between upstream blind wedge  14  and downstream blind wedge  14 ′. This, in turn, forces upstream surface  152  of upstream wedge  14  against inlet  120  of chamber  109  and downstream surface  150  of downstream wedge  14 ′ against outlet  122  of chamber  109 .  
         [0077]     As an alternative, the flow-through wedge assembly of  FIG. 1  may be replaced with a meter wedge assembly in chamber  109 . The meter wedge assembly includes a flow-through wedge with a bore diameter that is smaller than the I.D. of the pipeline and inlet orifice  107 . The bore diameter of the meter wedge assembly is known. Either the pipeline or isolation chamber  100  are fitted with instrumentation (known in the art) to measure the line pressure before the meter wedge assembly and after the meter wedge assembly in order to obtain the pressure drop. From this, known standards are consulted (such as API standards for differential pressure equations) in order to determine the liquid flow rate through isolation chamber  100 .  
         [0078]     While the invention has been described with a certain degree of particularity, it is manifest that many changes may be made in the details of construction without departing from the spirit and scope of this disclosure. It is understood that the invention is not limited to the embodiment set forth herein for purposes of exemplification, but is to be limited only by the scope of the attached claim or claims, including the full range of equivalency to which each element thereof is entitled.

Technology Category: f