Abstract:
A pressure containment device enables the installation of an everting liner without requiring a shipping container that can be pressurized. A pressure housing provides an inlet for receiving the liner and an outlet for installing the liner into the borehole. First and second movable belts have first and second sealing surfaces, respectively, for receiving the liner at the inlet of the pressure housing, and first and second interior surfaces for urging the first and second sealing surfaces against the liner when the pressure housing is pressurized. First rollers support the first and second movable belts within the pressure housing.

Description:
FIELD OF THE INVENTION 
     This invention relates to everting flexible liners, and, more particularly, to everting liners from an unpressurized reel. 
     BACKGROUND OF THE INVENTION 
     Flexible borehole liners may be installed in vertical or horizontal boreholes, pipes, ducts, and the like, for a variety of applications. One application installs liners with instruments in vertical or horizontal holes for the purpose of making measurements. Another application uses liners to line and support boreholes during horizontal drilling operations. A third application installs liners in sewers and other piping to renew and/or seal internal surfaces. 
     In drilling boreholes for emplacement of measurement or sampling devices, the common practice is to install the desired device in the borehole and then to seal the hole with a grouted liner to fill the entire hole with a sealing material. U.S. Pat. No. 5,176,207, issued Jan. 5, 1993, to Keller, teaches the use of a flexible tubular member to both seal and support a borehole and to carry instruments into a borehole as the flexible member is everted into the borehole. Instrumentation and sampling devices can then be placed directly in contact with the surrounding structure. 
     The flexible liners are normally installed from the interior of a pressure canister into the hole. The pressure canister contains the liner and the fluid pressure used to evert the liner into the hole. For very deep holes, the necessary liner volume becomes very large and requires the construction of a prohibitively large and expensive pressure canister from which to deploy the liner. 
     This problem is addressed in U.S. Pat. No. 5,154,936; 5,167,901; and 5,597,353, which provide a sphincter-like feed-through to deploy a liner. The sphincter feed-through is not well suited to install essentially flat and relatively fragile liners with attached instruments, or to seal about very small objects passing through a large sphincter. In some applications, the liner is deployed directly from a tension control device, which operates on a flattened liner. An attached cord for control of the everting liner often follows the liner. It is difficult for the sphincter device to seal about such cords. 
     Various objects, advantages and novel features of the invention will be set forth in part in the description which follows, and in part will become apparent to those skilled in the art upon examination of the following or may be learned by practice of the invention. The objects and advantages of the invention may be realized and attained by means of the instrumentalities and combinations particularly pointed out in the appended claims. 
     SUMMARY OF THE INVENTION 
     To achieve the foregoing and other objects, and in accordance with the purposes of the present invention, as embodied and broadly described herein, the apparatus of this invention is a pressure containment device for everting a liner. A pressure housing provides an inlet for receiving the liner and an outlet for installing the liner. First and second movable belts have first and second sealing surfaces, respectively, for receiving the liner at the inlet of the pressure housing, and first and second interior surfaces for urging the first and second sealing surfaces against the liner when the pressure housing is pressurized. First rollers support the first and second movable belts within the pressure housing. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The accompanying drawings, which are incorporated in and form a part of the specification, illustrate embodiments of the present invention and, together with the description, serve to explain the principles of the invention. In the drawings: 
     FIG. 1 is a side view of one embodiment of the present invention of a liner pressure control device. 
     FIG. 2 is an enlarged cross-sectional view of the upper belt system shown in FIG.  1 . 
     FIG. 3 is a further enlargement of the sealing mechanism of the upper belt system shown in FIG.  2 . 
     FIG. 4 is the top view of the upper belt system shown in FIG.  2 . 
    
    
     DETAILED DESCRIPTION 
     The present invention provides a means of everting and inverting very long liners without the use of a pressure canister for containment of the liner and for the control of the pressure applied to the interior of the liner during its installation. The liners can be installed directly from their shipping reel through this device. Yet the fluid pressure in the interior of the liner in the hole can be maintained high enough to force the liner into vertical or horizontal holes. The liners to be installed are relatively flat and often contain ports, tubing and other attachments for hole measurements. In some cases, the liners may be impregnated with uncured resins that are susceptible to being extruded from the liner material if not handled carefully when deployed into a pressurized volume from a lower pressure environment. 
     The main features of this invention are the pair of belts used to provide a seal of a system while still allowing a flat liner to be installed into a pressurized volume, and the surrounding sealing system used with those bells. 
     Referring now to FIG. 1, liner  10  is deployed from a shipping container (not shown), e.g., a reel device, into the pressure containment device entrance  12  of housing  14 . Liner  10  is fed between two belts  16  contained within housing  14 . Belts  16  are moved via crank  18  (FIG. 4) that extends from housing  14  and may be manually operated or driven through a motor/gear mechanism (not shown). As liner  10  is threaded through belts  16  and out of exit  22 , liner  10  is attached to entrance  24 , by e.g., a clamp fastener or the like, to allow liner  10  to be everted  26  into an opening  28 , such as a borehole, pipe, duct, or the like. 
     The interior of housing  14  is pressurized to force liner  10  to evert into the appropriate opening  28 . As liner  10  is pulled through entrance  12  of housing  14  by the pressure against everting liner  26 , belts  16  rotate on cylindrical roller pairs  32 ,  34  and  36 . All of the rollers are mounted on axles with appropriate bearings to minimize friction in their rotation. Rollers  32  are the entrance rollers at entrance  12 . Rollers  34  are for pressing edge portions of belts  16  together to reduce fluid leakage between the edges of the belts. The fluid pressure in housing  14  also serves to clamp belts  16  together at the edges to reduce the leakage between belts  16  and entrance  12 . 
     Thus, the pair of belts  16  forms a flattened envelope of liner  10  which allows liner  10  to be fed into opening  28  with a minimum loss of the driving fluid from the opening. A major advantage of belts  16  as a feed-through device is that liner  10 , which is normally in a flattened state on a shipping reel, can be deployed flat from the reel and flat into the opening  28 . This allows only a minimum of leakage and a minimum of abrasion damage to liner  10 . Liner  10  has a sealing coating on the outer surface (as wound on the reel), hence, the abrasion reduction is an important advantage. A third advantage of the belted feed-through is that the liner  10  often contains tubing and other hardware that causes irregularities in the cross section of the liner  10 . Inflated front rollers  32  and the flexibility of belts  16  easily accommodate these irregularities. Third rollers  36  are primarily for the tension control of belts  16 , which prevents belts  16  from being forced out of entrance  12  by the fluid pressure in housing  14 . Third rollers  36  are also formed of an inflatable material. 
     Referring now to FIGS. 1,  2 , and  3 , another set of sealing rollers  42  reduces leakage past the outer surface  44  of belts  16 , between belts  16  and device housing  14 . Belt  16  is forced against the rollers  42  by the fluid pressure in housing  14  and by the pressure of inflated roller  32 . This reduces the leakage path between outer surfaces  44  of belt  16  and sealing rollers  42 . Outer flow path  18  around sealing rollers  42  is controlled by shrouds  46  and felt wiper strip  48  on shrouds  46 . Any fluid leaking into the space between sealing rollers  42  and shrouds  46  is constrained to a slow net flow by the small passage, by felt strip  48 , and by the fact that rollers  42  rotate in the opposite direction of the leakage flow while liner  10  is being deployed into opening  28 . Sealing rollers  42  are held in shrouds  46  by the pressure of belt  16  against rollers  42  and, hence, sealing rollers  42  have no axles. This simplifies construction and provides the minimum clearance between sealing rollers  42  and shrouds  46 . In that case, shrouds  46  are made of a low friction material, such as nylon, or the like. 
     Small adjustable pressure relief valves  52  are located between sealing rollers  42  to allow adjustment of the pressure drop between rollers to achieve an optimum seal by controlling the differential pressure forcing belt  16  against rollers  42 . Another important factor is that adjustment of valves  52  is able to achieve a reasonable seal without excessive friction of rollers  42  against shrouds  46 . 
     Roller pairs  32  and  36  are inflated to tension belt  16  and to urge belt  16  against sealing roller  42 . Positioning rollers  54  prevent deflection of rollers  32  and  36  caused by the pressure of belts  16  against roller coverings  82 . Roller  54  is supported by an axle fixed to the side panel of housing  14 . 
     As shown in FIG. 4, belt  16  can be formed with a typical vee belt shape  56  on its edges to better run in grooves  58  on the rollers. Vee belt edge  56  also prevents the deflection of belt  16  by liner  10  from causing greater leakage at the edge  38  of belt  16 . Since belt  16  is captured in vee grooves  58  of front rollers  32 , belt  16  must stretch slightly laterally to its axis to accommodate the deflection by liner  10 . Belt  16  is preferably constructed with longitudinal strengthening tendons (not shown) to minimize the longitudinal stretch of belt  16  and to thereby provide better control of the ballooning of belt  16  out entrance  12  (FIG.  1 ). Tension rollers  36  prevent belts  16  from being distended at entrance  12  by the interior pressure of the device. Pressure rollers  34  also capture vee belts  56  at the edges of belts  16  in order to form a well-sealing shape of belts  16 . 
     The ends of sealing rollers  42  are fitted close to device housing  14  to minimize leakage past the ends of sealing rollers  42 . For that same reason, ends  62  of front rollers  32  are also fitted close to housing  14 . Belts  16  are likewise fitted close to sealing rollers  42  and to entrance rollers  32  to reduce the leakage. An external device (not shown) provides the replacement fluid needed in the interior of housing  14  to maintain the pressure required via valved inlet  64 . For an air driven system, a suitable device is a large air blower or compressor. For a liquid driven system, the fluid may be supplied by an ordinary pump such as a centrifugal pump operating at a set pressure. 
     Tubular system  72 , shown in FIG. 4, provides a fluid pressure to the interior of rollers  32  and  36  via a rotating seal  74 . The pressure applied through inlet  76  allows rollers  32  and  36  to be inflated via hollow axle  68  of rollers  32  and  36  and ports  78  into the interior of rollers  32  and  36 . Inflatable covering  82  of rollers  32  and  36  urges belt  16  against sealing rollers  42 . Inflatable coverings  82  of rollers  32  and  36  are maintained at a pressure adjustably greater than the pressure supplied in housing  14  at inlet  64  (FIG.  1 ). A pressure differential may be maintained by an adjustable valve (not shown) between inlet  76  and valve  64  (FIG.  1 ). An excess pressure aids rollers  32  and  36  to maintain a near cylindrical form and to more strongly urge belts  16  against sealing rollers  42 . 
     In operation, the interior pressure of housing  14  forces belts  16  against their several sealing rollers  42  and liner  10 . The higher the pressure, the greater the sealing force against sealing rollers  42  and liner  10 . The same pressure on inner belt surfaces  66  forces upper and lower belts  16  toward each other. Liner  10  is contained between upper and lower belts  16  and allows some leakage along any interstitial spaces in the liner bundle. However, the small size of the interstitial spaces due to the pressure forcing upper and lower belts  16  together and the long flow path along upper and lower belts  16  keeps the leakage at a minimum. This long flow path is an important difference from a sphincter-type feed-through such as shown in U.S. Pat. No. 5,597,353. The encapsulation of liner  10  between belts  16  also allows better conformation to the flat geometry of the liners of interest. 
     A further refinement of the device would be to enable housing  14  to be opened along its horizontal midplane to allow liner  10  to be laid between belts  16  instead of the simple threading of liner  10  through belts  16  as liner  10  is installed into the device. This refinement is complicated by the seal required on the midplane of the device. It is noteworthy that the belt system is usually symmetric about the plane of the belt contact. However, that is not a requirement of the device to allow its function. 
     Applications 
     The pressure containment device described herein allows the deployment of borehole liners for a wide variety of applications. Liners can be deployed in confined borehole access situations, since the device has much smaller volume than the common pressure canister currently used to house and deploy the liner. The liner can be retrieved and wound on a reel with easy access to the liner as it passes onto the reel allowing manual control of the configuration on the reel to improve the reel capacity and to minimize potential damage to the hardware often attached to the liner. The liner can also be level wound on the reel by hand without a costly level winding mechanism otherwise required inside a pressure canister. 
     When used in conjunction with a tension control device between a shipping reel and housing  14 , very long and heavy liners can be retrieved more safely from deep horizontal holes. Normally, the drag tension of the liner during retrieval compresses the liner badly on the reel inside a pressure canister. A tension control device allows the separation of the liner tension control from the leakage control required for everting liner installations and retrievals. 
     Installation of liners in very long slender holes for the purpose of towing instruments of various kinds requires the management of very long lengths of liners (e.g., 1600 ft. of 2 inch diameter tubular liner). The present device allows those long lengths to be controlled by hand, free of the restrictions of retrieval into a pressure canister. Also, multiple lengths of a liner may be serially attached to form the very long length since the liner can be accessed from outside the pressurized volume. Another advantage is the elimination of the hazard of large pressurized volumes of fluid in the pressure canister otherwise needed. 
     It is also possible with this device to deploy liners for greater distances in horizontal passages with many turns and the associated friction of dragging the liners into the holes. Many liners are deployed without the use of a pressure canister by using a liquid driver, e.g., simply pouring water into the liner as it everts downward into a hole. Those liners are too bulky and too long for use of a pressure canister of reasonable cost. If a greater pressure is needed, a vertical riser pipe is added to the hole entrance to achieve a greater head of water. The device of the present invention allows liquid-driven installations to be affected at a much higher driving pressure than can be practically attained by the hydrostatic water installation technique. Consequently, the liners can be installed in much longer continuous segments at less cost than piecemeal installations with the associated extra excavations required. 
     It is also expected that liners can be installed with this device with piping interior to the liner for the purpose of emplacement of the pipe into a horizontal hole formed by an appropriate means such as described in U.S. Pat. No. 5,816,345, issued Oct. 6,1998. The belts can be extended in length and formed of sufficiently elastic material that the belt conforms to the outer cylindrical shape of a pipe under the driving force of the interior fluid pressure in the device. It may be necessary to increase the roller diameters to accommodate the larger pipe diameter. Such piping can be installed with or without a surrounding liner. In that case, this device eliminates the need for the hose canister described in U.S. Pat. No. 5,803,666, issued Sep. 8, 1998, for use in augmentation of horizontal drilling. The liner and the attached pipe/casing can both be installed through this device to control the leakage of the driving fluid. 
     A cord is often attached to everting liners to facilitate their retrieval. As this cord follows the liner into the hole, the seal around the small cord is difficult with a large sphincter type of gland. However, the small cord is easily passed, with a good seal, between the pair of belts in this invention. 
     A further advantage of this device is that the liners passing between the belts are not sliding on the belts. This reduces the problem of wear that must accumulate in stationary sphincter type glands. The sliding seals of this system are mainly at machined surfaces such as the sealing rollers and the end seals of the front rollers. These are ordinary seals and seal materials and less likely to wear than the elastic orifice of a sphincter. 
     Although not shown, the leakage out of this device is replaced by an air blower (if air driven) or by a liquid pump (if a liquid system). If the liquid leakage is large, it can be collected within spray shields at the entrance and pumped back into the interior of the pressurized system. 
     The foregoing description of the pressure containment device according to the present invention for everting a very long liner into a borehole has been presented for purposes of illustration and description and is not intended to be exhaustive or to limit the invention to the precise form disclosed, and obviously many modifications and variations are possible in light of the above teaching. 
     The embodiments were chosen and described in order to best explain the principles of the invention and its practical application to thereby enable others skilled in the art to best utilize the invention in various embodiments and with various modifications as are suited to the particular use contemplated. It is intended that the scope of the invention be defined by the claims appended hereto.