Abstract:
A fitting for inserting a pig into a pipeline. The fitting comprises a cast body having a first end for connecting to a first end of a pipeline and a second end for connecting to a second end of the pipeline. The cast body further comprises a third end arranged at a predetermined angle to the first and second end of the cast body. A retractable guide within the cast body can be at least partially inserted into a run portion of the cast body for delivery or retrieval of the pig.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
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     STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
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     REFERENCE TO SEQUENCE LISTING, A TABLE, OR A COMPUTER PROGRAM LISTING COMPACT DISC APPENDIX 
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     BACKGROUND OF THE INVENTION 
     The present invention relates generally to an apparatus and method for inserting and retrieving pipeline pigs into pipelines, and more specifically to an apparatus and method for installing an in-line piggable wye fitting into a pipeline for the insertion and removal of in-line inspections tools. 
     The primary purpose of pipeline pigs is to clean and obtain vital information concerning the integrity of the pipeline. The pigs used in most oil and liquid products pipelines are typically used to remove paraffins, sludge, and water from the pipeline. The most common pigs that are used in oil and liquid products pipelines are in the shape of spheres or bullets that are made of a polyurethane material. As a result, these foam pigs are lightweight, easy to work with, and able to negotiate uncommon piping, fittings, and valves. Other types of cleaning pigs are solid cast pigs and steel mandrel scraper pigs. In other applications, such as oil and gas and natural gas pipelines, intelligent pigs (also called in-line inspection (ILI) tools) are used to determine the integrity of the pipe wall for such conditions as corrosion, wall thinning, and other defects that may affect the pipeline operations. Common types of these intelligent pigs include ultrasonic (UT) and magnetic flux leakage (MFL) induced sensors, such as the SmartScan sensors made by GE and many others well known in the art. 
     A pig must be launched into the pipeline for cleaning or inspection (typically by a launching station) and removed from the pipeline (typically by a receiving station) to allow for normal operation of the pipeline when the pig is in the pipeline. The pig is typically introduced into the pipeline by means of a bypass loop that diverts the flow of the pipeline product to the launch vessel by the use of valves and other pipeworks. When the pipeline product is diverted to the launcher, a valve downstream of the launcher is opened and the pig is introduced into the pipeline by means of the launching station. In most cases, the tool travels along the length of the pipeline with special seals that allow the product flowing in the pipeline to push the tool. As the tool travels, it cleans the pipeline and/or performs inspections on the pipeline and is received into the receiving vessel at the end of the pipeline run. The receiver is similar to the launcher in that a bypass loop is established with valving and pipeworks to divert the tool into the receiver without substantially disrupting the pipeline operations. In most oil and liquid products pipelines, launch and receive stations are permanently installed at various locations during installation of the pipelines to allow the cleaning of paraffin deposits and other mineral build-ups. Because the valving and pipeworks of these pipeline systems were designed for the use of pigs (i.e., the valves in these pipelines typically include an orifice the same size as the internal pipeline and consistently sized piping was used between launch and receive stations), the pigs are able to inspect a long length of pipeline between the launch and receive stations. 
     The most comprehensive method to give an overall assessment of a natural gas and crude pipeline is to run intelligent pigs that can map many inspection points along the internal length of the pipeline. The challenge in using intelligent pigs in these pipelines is the piping configurations that prevented previous technologies from gathering the required information on a cost effective basis, often called “unpiggable” pipelines. Pipelines can be “unpiggable” for a variety of reasons, including changes in diameter (because of compressibility of gas, the use of multi-diameter pipes is common), presence of unsuitable valves, tight or mitered bends (less than three diameters), low operating pressure, low flow or absence of flow, lack of launching and receiving facilities, dented or collapsed areas, and excessive debris or scale build-up. Natural gas pipelines are particularly known for having a high number of “unpiggable” pipelines. Further, in natural gas pipelines, products rarely produced deposits onto the pipe walls and did not require cleaning during the service life of the pipelines. Thus, the use of pipeline cleaning or in-line inspection pigs, and the use and installation of launch and receive stations, were traditionally not common in natural gas pipelines. Rather, the integrity of the pipeline was monitored by various means such as by using sacrificial corrosion coupons (e.g., pipe samples taken from the pipeline wall), visual inspection, and/or digs to perform pipe wall thickness analyses to predict corrosion rates. Unfortunately, these methods are only indicative of the conditions at the specific spots of inspection. 
     Techniques were developed for a method and system that uses “hot tap” technology to access the existing pipeline by adding a new connection to the pipeline without interruption of service. In this technique, after a 45 degree hot tap is made in the pipeline, a chute housing is connected to the hot tap valve. The chute within the housing is inserted through the hot tap valve to provide a path for the inspection tool to follow into the pipeline. After the chute is inserted, the bypass piping with the launch vessel is assembled to the pipeline and chute housing, and gas is allowed to flow from the pipeline so as to enter behind the inspection tool. The mainline valve is closed and the bypass valve is opened launching the tool into the pipeline. The inspection tool proceeds through the pipeline performing pipeline integrity tests and then is removed from the pipeline when it enters into the receiver station that is substantially similar to the launch station. At both the launching and receiving sites, the chute is retracted and the chute housing and associated pipeworks are removed prior to insertion of the completion plugs. The completion plugs are set to allow the hot tap valves to be removed. Once the completion plug is set, a blind flange is installed and the pipeline can be covered. A similar system is described in WO 2005/119117, incorporated herein by reference. 
     Although this “hot tap” method has been used in industry, it suffers from numerous and significant disadvantages. The complexity of the hot tap technique for insertion of launch and receive vessels to be connected to chute housings requires customization for every application. Another primary disadvantage is that the equipment for introducing and retrieving an inspection tool into and from a pipeline by the hot tap method are extremely large and heavy. The chute housings with the actuators can extend over 50 feet above the pipeline requiring considerable lifting capabilities as well as supports for the equipment. Using this equipment requires detailed planning for transportation, assembly, and use, such as acquiring right of ways for transportation of the equipment to the work site. Additionally, the equipment is limited in application due to the complexity of the tool geometry, which lends itself to larger diameter pipelines, so inspection tools typically cannot not be inserted into smaller diameter pipelines according to this “hot tap” method. Another problem is the high cost for the use of such chute housings and launch and receive vessels and associated methods for use and installation. Typical launch/receive stations (including the chute housings) for this “hot tap” method require a large investment in piping and facilities with little payback, and often run into the millions of dollars per station. As a result, many pipelines cannot be efficiently and/or effectively inspected, if even inspected at all. 
     What is needed is an apparatus and method for inserting a pig or inline inspection tool into a pipeline that will simplify the design, installation, and operation of fittings and associated pipeworks for launching/receiving inspection tools, reduce installation time of such equipment, reduce the equipment size, allow for temporary launch/receive facilities, reduce capital and operating costs, allow for inspection of previously unpiggable pipes (such as smaller diameter pipelines), and allow for more frequent and easier insertion and removal of tools into the pipeline. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  illustrates a preferred embodiment of the present invention including an exterior view of the in-line piggable wye fitting. 
         FIG. 2A  illustrates a cross-sectional side view of the piggable wye fitting shown in  FIG. 1  with the guide withdrawn from the pipeline. 
         FIG. 2B  illustrates a cross-sectional side view of the piggable wye fitting shown in  FIG. 1  with the guide extended into the pipeline. 
         FIG. 3  illustrates a preferred embodiment of the piggable wye fitting shown in  FIG. 1  connected to a pipeline with a launch vessel and temporary valving. 
         FIG. 4  illustrates a preferred embodiment of the piggable wye fitting shown in  FIG. 1  connected to a pipeline without a launch vessel and temporary valving. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring to  FIG. 1 , a preferred embodiment of the present invention is illustrated.  FIG. 1  shows an in-line piggable wye fitting  2 , including sweep piping  4 , pup piping  6 , wye body  1 , and flange  12  attached to an extended branch of sweep piping  4  that is inset into wye body  1  (the inset being shown in more detail in  FIGS. 2-3 ). Piggable wye fitting  2  allows the insertion and retrieval of a pig or inspection tool into a pipeline. Pup piping  6  (a first fitting portion of wye fitting  2 ) is preferably the same diameter and material as the pipeline to which pup piping  6  is connected and is substantially straight and parallel to the pipeline to which it is connected so as to not impede flow in the pipeline during normal operation. Indeed, pup piping  6  can alternatively be the pipeline itself. Pup piping  6  connects piggable wye fitting  2  and the launch/receive vessel (not shown) to the pipeline by means of welding and/or flanged ends. The piggable wye fitting  2  in combination with a launch or receive vessel and corresponding pipeworks is generally termed a launch or receiving station. 
     As indicated, in one embodiment pup piping  6  is preferably connected to the pipeline by welding or flanging each end of pup piping  6  directly in-line to the pipeline. Thus, a first end of pup piping  6  may be connected to a first end of the pipeline, and a second end of pup piping  6  may be connected to a second end of the pipeline to permit normal operation of the pipeline through wye body  1  and pup piping  6 . This portion of wye body  1  between the first and second ends of pup piping  6  is referred to as the run portion of wye body  1 . Sweep piping  4  (a second fitting portion of wye fitting  2 ) is inset into wye body  1  and connects wye fitting  2  to launch or receive facilities through flange  12 . In a preferred embodiment, wye body  1  is a cast body, to which flange  26  is bolted and sweep piping  4  is inset. 
     In a preferred embodiment, sweep piping  4  is the same diameter and material as the pipeline to which pup piping  6  is connected. Guide feed  8  (shown in  FIGS. 2A and 2B ) extends and withdraws guide  32  (shown in  FIGS. 2A and 2B ) into and out of the run portion of wye body  1  in order to divert the pipeflow into sweep piping  4  and the inspection tool into or out of the launch or receive vessels. Depending on the directional flow of fluid in this portion of wye body  1 , the orientation of wye fitting  2  as shown in  FIG. 1  can be connected to either the launching vessel or the receiving vessel. 
     In a preferred embodiment, wye fitting  2  has a radial sweep of three pipe diameters as measured between pup piping  6  and sweep piping  4 . Such a radial sweep allows current technology inspection tools (that often have multi-units forming a train of sensing hardware) to more easily navigate into and out of the pipeline. In this embodiment, the wye body  1  is made, or cast, with a predetermined angle (identified as angle A in  FIGS. 2A and 2B ) with a radius of three times the nominal line size to allow for the inspection tool to enter and exit the pipeline, such as approximately a 45 degree angle. 
     Referring to  FIGS. 2A and 2B , a preferred embodiment of the present invention is illustrated showing cross-sectional side views of piggable wye fitting  2  with guide  32  withdrawn from ( FIG. 2A ) and extended into ( FIG. 2B ) the run portion of wye body  1 . Piggable wye fitting  2  as illustrated in  FIGS. 2A and 2B  includes sweep piping  4 , pup piping  6 , guide feed  8 , wye body  1 , and guide assembly  10 . In a preferred embodiment, guide feed  8  includes feedscrew shaft  22 , feednut  24 , gasketed plate  26 , and packing gland  28 . In this embodiment, the housing of guide feed  8  is cast wye body  1 , as shown in  FIG. 1 . The top of guide feed  8  is enclosed by gasketed plate  26  that is bolted to wye body  1 . Feedscrew shaft  22  can be rotated (by way of a rotator attached to feedscrew shaft  22 ) counter-clockwise a predetermined amount of turns until the guide is completely withdrawn into the fitting housing of guide feed  8  so as to not impede pipe flow, or conversely rotated clockwise for extension into what is effectively an extension of pup piping  6 . 
     A few examples of such a rotator include a handle or wheel, which can be attached to a portion of feedscrew shaft  22  that extends through gasketed plate  26 . An indicator  5  can be located on the outer feedscrew extension that shows how deep the guide is placed into the pipeline. Packing gland  28  encases elastomeric seals in gasketed plate  26  and against feedscrew shaft  22 . Guide feed  8  is connected to guide assembly  10  by a feed attachment such as feednut  24 , which is preferably attached to guide assembly  10  by screws and is preferably made of a brass alloy to aid in lubrication and ensure an even actuation of guide feed  8 . Guide assembly  10  includes guide  32 , guide support  34 , and guide extender  36 . Guide  32  is extended into the run portion of wye body  1  by guide feed  8  to divert the pipeflow into sweep piping  4  and an inspection tool into or out of the launch or receive vessels and the pipeline. Guide  32  is attached to guide extender  36 , which is connected to feednut  24 . In one embodiment, guide extender  36  is rolled plate that conforms to the outside diameter of the sweep piping  4 . Guide support  34  is attached to the bottom of guide  32  to provide support and a positive stop of guide  32  at the bottom of the pipeline wall of pup piping  6 . 
     It will be apparent to one of ordinary skill in the art that the specifications of wye fitting  2  can be modified for insertion or extraction of an inspection tool into a pipeline depending on the particular situation. For example, the neck of sweep piping  4  and feedscrew  22  can be extended to allow for operation of the wye fitting above ground level that does not require excavation during use. In another embodiment, rather than using a feedscrew to position a guide into the pipeline, a swing check can be utilized that retracts and extends guide assembly  10  into the pipeline. 
       FIG. 3  illustrates a preferred embodiment of the piggable wye fitting shown in  FIG. 1  connected to a launch vessel and corresponding pipeworks to allow for normal operation of the wye fitting. As depicted in  FIG. 3 , the orientation of wye fitting  2  along with flow F of pipeline fluid indicates that the wye fitting is to be utilized in a launching station for the introduction of an inspection tool or pig into the pipeline. It will be apparent to one of ordinary skill in the art that the orientation depicted in  FIG. 3  can be reversed to utilize the piggable wye fitting in a receiving station setup. It will also be apparent to one of ordinary skill in the art how the arrangement and operation of the launching/receiving vessels and valves and other associated pipeworks operate in conjunction with the piggable wye fitting. 
     As shown in  FIG. 3 , in-line piggable wye fitting  2  is installed on pipeline  44  and connected to launch vessel  42 . Mainline valve  54  is connected to pipeline  44  and exists on the pipeline upstream of piggable wye fitting  2 . Bypass valve  56  is connected to pipeline  44  via bypass flange  13  and launch vessel  42  and exists on pipeline  44  upstream of piggable wye fitting  2  and mainline valve  54 . It will be apparent to one of ordinary skill in the art that launch vessel  42  can be a common launching vessel for the introduction of pigs or in-line inspections tools into a pipeline, and that its specifications may vary depending upon the requirements of the pipeline, pipeline fluid, and/or inspection tool. Full port ball valve  52  is connected on one end to flange  12  of wye fitting  2  and on the other end to launch vessel  42 . In a preferred embodiment, wye fitting  2  stays permanently connected to pipeline  44  during normal operation of the pipeline by keeping the guide withdrawn from the pipeline so as to not impede pipeline flow. Before an inspection tool has been inserted into the pipeline (or after an inspection tool has been utilized and removed from the pipeline), launch vessel  42 , full port ball valve  52 , and bypass valve  56  are not needed for normal operation of the pipeline and can be removed from the piping configuration (as shown in  FIG. 4 ). In this situation, flange  12  of wye fitting  2  and bypass valve flange  13  are temporarily capped until the launch vessel and corresponding valves and pipeworks need to be re-assembled for insertion or retrieval of the inspection tool. 
     In another preferred embodiment, a method is used to directly insert and retrieve an inspection tool into a pipeline according to the following procedure. In operation, and after a piggable wye fitting  2  and necessary pipeworks has already been connected to a pipeline using procedures described above and well known to those of ordinary skill in the art, full port ball valve  52  is bolted to flange  12 . A completion plug setter is removed through valve  52 , valve  52  is closed, and the completion plug setter is bled down of internal pressure. Launch vessel  42 , bypass valve  56 , and other pipeworks are connected to pipeline  44  and full port ball valve  52  using procedures well known to those of ordinary skill in the art. A similar operation is repeated downstream at an equivalent receiving station. After the inspection tool is assembled in launch vessel  42 , and with bypass valve  56  and full port ball valve  52  opened according to procedures well known to those of ordinary skill in the art, mainline valve  54  is slowly closed, reducing flow in the pipeline at guide  32 . Once the flow has been diverted, guide  32  is linearly actuated into the pipeline by rotating feedscrew  22  clockwise a predetermined number of turns until guide support  34  rests on the bottom of the inside pipe wall of pup piping  6 . The guide is at this point set and able to steer the pig or inspection tool into the main pipeline. The tool is allowed to travel through the pipeline and inspect the pipeline according to procedures well known in the art. 
     A similar installation and operation procedure is repeated at the receiving station to allow the inspection tool to exit the main pipeline through a second piggable wye fitting into a receiving vessel. When the inspection tool is received into the receive vessel, the pipeline can be restored to normal operation and the guide can be withdrawn from the pipeline by rotating the feedscrew counter-clockwise a predetermined amount of turns until the guide is completely withdrawn so as to not impede pipeline flow. 
     In another preferred embodiment, a method is used to insert the piggable wye fitting into an existing and operational line according to the following procedure. Line stops are installed near the proximity of the location where piggable wye fitting is to be installed. A bypass loop around the insertion point of the piggable wye fitting can be established through the line stops. The piping between the line stops is de-pressurized, the necessary amount of pipeline between the line stops is removed, and a piggable wye fitting is installed in the removed portion of the pipeline by welding the ends of the piggable wye fitting pup piping to the ends of the pipeline. The mainline pipe is pressured between the line stops and the line stops are removed. Completion plugs are installed at all necessary locations and the site is returned to normal conditions. An inspection tool can be inserted into and retrieved from the pipeline according to the procedures described above. 
     It will be apparent to one of skill in the art that described herein is a novel apparatus and method for inserting and retrieving an in-line inspection tool into a pipeline by the use of an in-line piggable wye fitting. While the invention has been described with references to specific preferred and exemplary embodiments, it is not limited to these embodiments. For example, it will be apparent to one of skill in the art that the piggable wye fitting can be installed in new construction or as a retrofit to an existing pipeline. The invention may be modified or varied in many ways and such modifications and variations as would be obvious to one of skill in the art are within the scope and spirit of the invention and are included within the scope of the following claims.