Abstract:
A device for establishing an environment of a required fluid inside a length of pipe, comprising two pipe-engaging members adapted to engage the interior surface of the pipe at respective positions spaced therealong, and means for introducing said fluid into the interior of the pipe between said engaging members, each pipe-engaging member comprising a casing for contacting the pipe interior surface and containing an inflatable element; wherein the casing of each engaging member includes at least a portion of stretchable material for enabling expansion and contraction of the casing in a direction radially of the pipe, for engaging a range of internal pipe sizes.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    This invention generally relates to a device for blocking-off part of the interior of a pipe, for the purpose of establishing and maintaining an environment of a required fluid in the length of pipe. As used herein, the term “pipe” is to be understood as including other pipe-like members, or structures of wholly or partially separate pipe elements, which might be required to have a part thereof blocked-off from the remainder thereof, for similar or other purposes. 
         [0003]    The present invention has been devised particularly, but not exclusively, for when an atmosphere of inert gas such as argon is required to be established in the interior of a length of pipe where two pipe elements are required to be joined to one another by welding circumferentially of the pipe. One known way in which this can be done is by disposing two blocking members within the length of pipe with the welding region between them, each blocking member being inflatable so as to establish firm contact with the inside surface of the pipe. When the two blocking member have been thus caused to engage and block the pipe, the required atmosphere of inert gas can be established between them by feeding the inert gas between the blocking members at a rate which corresponds to the rate at which the gas escapes through the welding region, prior to completion of the welding operation. 
         [0004]    2. Description of the Relevant Art 
         [0005]    Devices for operating in this manner are disclosed in my British patent GB 2420837B and application GB 2383108A. Pipe blockers are disclosed in my patent GB 2361283B and application GB 2413165A. In GB 2383108A, each blocking member comprises a casing having a peripheral portion for engaging the pipe interior surface, the casing containing a ring-like inflatable element and having a part which closes the space within the inflatable element. The ring-like inflatable element conveniently is an inner-tube, as used in vehicle tires. GB 2420837B discloses a device in which two pipe-engaging members with respective inflatable elements do not each completely block the pipe but instead have casings with central openings, the casings thereof being joined by a sleeve portion so that, in use, the space occupied by the inert gas is defined by the engaging members, the sleeve, and the pipe interior surface. In the arrangement of the latter patent, the use of the sleeve reduces the volume required to be filled with the inert gas. 
         [0006]    Although a pipe may have a specific nominal size, e.g. 2″ (50 mm), 3″ (76.2 mm), 6″ (150 mm), etc., the actual physical dimensions of a pipe can vary greatly. The wall thickness varies, dependent on the conditions in which the pipe is to operate, e.g. the fluid it is intended to contain and the pressure thereof. Thus steel pipes of a nominal size of 2″ (50 mm) may have an outside diameter of 60.33 mm and an inside diameter from 57.03 mm (schedule 5) to 42.91 mm (schedule 160). A steel pipe of nominal size 3″ (76.2 mm) may have an inside diameter ranging from 84.68 mm (schedule 5) to 66.64 mm (schedule 160). A pipe of nominal size 12″ (300 mm) may have an outside diameter of 323.85 mm and an inside diameter ranging from 315.47 mm (schedule 5) to 257.21 mm (schedule 160). In the last mentioned case, for example, any pipe-engaging member, if it is to be capable of use with the entire range of pipe internal diameters which are to the nominal pipe size, has to cope with a variation of some 58 mm in the pipe internal diameter. Otherwise, it is necessary to provide a large number of different sizes of pipe-engaging members to co-operate with the different pipe internal diameters. It is broadly an object of the embodiments disclosed herein to address this requirement. 
       SUMMARY OF THE INVENTION 
       [0007]    According to one embodiment, a device is provided for use in establishing an environment of a required fluid inside a length of pipe, comprising two pipe-engaging members adapted to engage the interior surface of the pipe at respective positions spaced therealong, for defining a volume in the interior of the pipe between said engaging members into which the fluid can be introduced, each pipe-engaging member comprising a casing for contacting the pipe interior surface and containing an inflatable element; wherein the casing of each engaging member includes at least a portion of stretchable material for enabling expansion and contraction of the casing in a direction radially of the pipe, for engaging a range of internal pipe sizes. 
         [0008]    The stretchable material may be provided at such a position in relation to the casing as to engage the internal pipe surface when in use. To achieve this, the stretchable material may comprise the entire casing, or may comprise a radially outwardly-facing, circumferentially extending, portion of the casing. In the latter case, the rest of the casing need not be stretchable. 
         [0009]    The stretchable material may comprise an elastomeric sheet material, conveniently a closed-cell foam material of polychloroprene, preferably with a stretchable fabric layer. Such sheet materials, e.g. that commonly referred to as “neoprene”™ are widely used for the manufacture of garments such as “wet suits” for diving or other water sports activities. By way of example it may be 2 mm-5 mm thick. 
         [0010]    A device in accordance with the embodiments herein may be of the general configuration disclosed in my patent GB 2383108 or GB 2420837, but with the provision in each of the pipe-engaging members of the appropriate portion of the stretchable material. 
         [0011]    When an embodiment of a device is intended for use in larger sized pipes, e.g. of about 300 mm nominal size upwards, the pipe-engaging members may each comprise a casing of annular configuration containing a ring-like inflatable element, the casings being joined by a sleeve portion of flexible material adapted to constrain the required fluid in an annular space defined, in use, between the engaging members, the sleeve portion, and the pipe interior surface. 
         [0012]    The means for introducing the fluid may comprise pipage, i.e. a number of pipe portions which collectively provide the necessary passages for conveying fluid, for introducing the fluid firstly to the inflatable elements for inflating same and thereafter, by way of a release valve, into the space between the pipe-engaging members (into the annular space defined as aforesaid in the case where the pipe-engaging members are joined by a sleeve portion). 
         [0013]    For use with smaller pipe, a device may comprise pipe-engaging members which each completely fill the interior space of the pipe at the position where they are disposed, the pipe-engaging members being connected only by the pipage aforesaid, for introducing fluid into the pipe-engaging members for inflating same. 
         [0014]    In such a device, the pipage may include a pipe which is flexible (e.g. of a suitable plastics or rubber-type material), but of sufficient rigidity to keep the pipe-engaging members spaced from one another when the device is inserted into a pipe at an opening therein (e.g. from an end thereof) and moved along the pipe by pushing the device from the position of the opening. 
         [0015]    Smaller pipes commonly include bends where the pipe is bent through a comparatively small radius or where two adjacent straight pipe portions extending at  90  or  45  to one another are joined by an appropriate elbow fitting which provides the bend. To assist in passing a device around such a corner in a pipe, the device may be provided with one or more guide members. 
         [0016]    Each guide member preferably has a smooth profile with an external surface of dimension able to move readily lengthwise within a pipe and tapering in both directions lengthwise of the pipe. Such a guide member is readily able to move within the pipe including moving around elbows or curved portions of relatively tight radius. Such guide members may be spherical, or possibly of prolate spheroidal shape (e.g. generally in the shape of a rugby ball or American football) with the largest dimension extending lengthwise of the pipe. 
         [0017]    The guide members may comprise at least one guide member on each side of each pipe-engaging member, positioned relatively closely to the pipe-engaging members in the direction lengthwise of the device (and hence lengthwise of pipe with which it is to be used). 
         [0018]    The transverse dimension of each guide member may be slightly greater than that of each pipe-engaging member when the pipe-engaging member is not inflated; this enables the device to be supported in a pipe primarily by the guide members and to be able to move relatively freely therealong, without being impeded by contact of the pipe-engaging members with the internal surface of the pipe. 
         [0019]    Conveniently, the guide members may be supported by being received on respective pipe portions of the pipage of the device. 
         [0020]    In the case of a device which is intended for use when welding pipes of relatively small diameter, e.g. 50 mm or 100 mm, it will be understood that such welding will be taking place in close proximity to whatever pipage is provided between the two pipe-engaging members. Therefore, plastics or other pipe materials vulnerable to damage from heat may be provided with a sleeve portion or portions of suitable protective, heat-resisting, material. 
         [0021]    In the case of a device including a sleeve between the pipe-engaging members, the sleeve member is closest to the welding location and so may be of, or include a covering of, heat-resistant material. Adjacent casing parts of the pipe-engaging members may also be of, or include, heat-resistant materials. 
         [0022]    A further feature which may be provided in a device for blocking off part of the interior of a pipe, assists the positioning of the pipe-engaging members approximately equally distant from a location therebetween in which welding is to be carried out. The pipage, or sleeve, extending between the pipe-engaging members may be provided with a visible indicator of the approximate midway position between the pipe-engaging members, of high visibility. The high visibility may be afforded by an element of bright color, or possibly of a luminous material. 
         [0023]    Such an element may be seen through the small gap existing where welding is to be carried out, and hence used to position the device lengthwise of the pipe. 
         [0024]    According to another embodiment a pipe-engaging member is provided for a device. 
         [0025]    According to yet another embodiment, a device is provided for use in establishing an environment of a required fluid inside a length of pipe, comprising two pipe-engaging members adapted to engage the interior surface of the pipe at respective positions spaced therealong, for defining a volume in the interior of the pipe between said engaging members into which the fluid can be introduced, each pipe-engaging member comprising an inflatable element for causing engagement of the pipe-engaging member with the pipe interior surface, the pipe-engagement members being carried by at least one support element whereby the members can be moved along within a pipe while being held spaced from one another, wherein there is provided at least one guide member for guiding the device relative to the pipe during movement thereof within the pipe. 
         [0026]    The guide member(s) or at least one thereof is preferably carried by the support element(s). 
         [0027]    The support element(s) preferably comprises pipage for supplying fluid to at least the pipe-engaging members. 
         [0028]    The configuration of the guide member(s) is preferably as aforesaid. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0029]    These and other features of the invention will now be described by way of example with reference to the accompanying drawings, of which: 
           [0030]      FIG. 1  is a perspective view of a first embodiment of a device. 
           [0031]      FIG. 2  is a diagrammatic section through the device of  FIG. 1 . 
           [0032]      FIG. 3  is a view of a further embodiment of a device. 
           [0033]      FIG. 4  is a diagrammatic, partly sectioned, view of the device of  FIG. 3 . 
       
    
    
       [0034]    While the invention may be susceptible to various modifications and alternative forms, specific embodiments thereof are shown by way of example in the drawings and will herein be described in detail. The drawings may not be to scale. It should be understood, however, that the drawings and detailed description thereto are not intended to limit the invention to the particular form disclosed, but to the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the present invention as defined by the appended claims. 
       DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0035]    Referring firstly to  FIGS. 1 and 2  of the drawings, these show a device indicated generally at  10 , for blocking-off part of the interior of a pipe, suitable for use when welding two separate or partially-separate lengths of pipe together to form the pipe. The device comprises two pipe-engaging members indicated generally at  12 ,  14  connected to one another by a sleeve member indicated generally at  16 . 
         [0036]    The pipe-engaging members  12 ,  14  are generally the same as one another. The member  12  comprises an annular casing indicated generally at  18 , which is somewhat of toroidal configuration, comprising spaced annular wall portions  20 ,  22  which face lengthwise of the device, i.e. along the central axis of a pipe when the device is in use. The radially outermost edges of the wall portions  20 ,  22  are joined by a radially outwardly facing circumferential wall portion  24 . The radially innermost edges of the wall portions  20 ,  22  are connected, e.g. by stitching, to spaced circumferential parts respectively at the end of the sleeve portion  16  and spaced along the sleeve portion from the end. The casing  18  accommodates a ring-like inflatable element  24  which conveniently is an inner-tube, such as is used in vehicle tires, e.g. the tire of a mobility scooter, motor scooter, motorcycle, car or truck according to the size required. The pipe-engaging member  14  is of the same construction as the pipe-engaging member  12 , being disposed at the opposite end of the sleeve portion  16 . 
         [0037]    The casing  18  of each of the pipe-engaging members has its wall portions  20 ,  22  made of a flexible fabric-based material, e.g. a polyurethane coated fabric of polyamide or other fiber, with appropriately-shaped pieces thereof stitched together to provide the required configuration. The circumferential wall portion  24  is, however, of a stretchable material, conveniently an elastomeric sheet material. A closed-cell foam material of polychloroprene (“neoprene”) having a stretchable fabric layer, has been found to be suitable. The stretchable fabric layer is provided on the exterior surface of the circumferential portion  24  of the casing  18 . When the inflatable element  24  is inflated, it will stretch the stretchable material of the portion  24  to a configuration, if unconstrained by being within a pipe, shown in broken lines in  FIG. 2 . Hence, a relatively wide range of internal diameters of pipe is able to be engaged by the pipe-engaging member. 
         [0038]    The sleeve portion  16  of the device is of tubular form, defining a central through-passage between opposite ends of the device. The sleeve portion  16  is of fabric-based material as for the wall portions  20 ,  22  of the casings, suitably coated for fluid tightness (although it will be appreciated that the joining of fabric elements together by stitching inherently provides openings through which a fluid can pass so that the device as a whole is not completely fluid tight). The sleeve portion  16  may comprise pockets extending lengthwise of the sleeve portion, for receiving a number of circumferentially-spaced semi-rigid stiffening elements one of which is indicated at  28 , for facilitating handling of the device and its insertion into and correct positioning within a pipe by helping the sleeve portion to remain in an elongate form. Such stiffening elements may be of plastics or any other suitable material. The external surface of the sleeve portion  16 , the wall portion  22  of the casing of pipe-engaging member  12  and the facing wall portion of the pipe-engaging member  14  are preferably provided with a heat-resistant surface covering or are entirely of a heat-resistant material, possibly incorporating a glass fiber fabric or of or including a heat-resistant silicone material, for resisting damage from welding splashes when welding is carried out in the vicinity thereof. 
         [0039]    For inflating the inflatable members  24  of the pipe-engaging members  12 ,  14 , pipage is provided for supply of inert gas, e.g. argon, to the inflatable elements. A pipe  30  for connection to a supply of such gas leads firstly to a T piece to which is connected the inflation stem  32  of the inflatable element  24  of the pipe-engaging member  12 . A further pipe portion  32  then continues through the interior of the sleeve portion  16  to the inflation stem of the inflatable element in the pipe-engaging member  14 . Between the inflatable elements, there are two T pieces  34 ,  36  leading to respective pressure release valves  38 ,  40  respectively. The pressure release valves  38 ,  40  are set to open at a pressure slightly greater than that required to inflate the inflatable elements within the casings of the pipe-engaging elements  12 ,  14  and to cause the pipe-engaging members firmly to engage the internal surface of a pipe, until further inflation of the inflatable elements is constrained. Such pressure which causes the pressure release valves  38 ,  40  to open is less than that at which damage to the pipe-engaging members might occur due to over-inflation. 
         [0040]    The sleeve portion  16  is provided with a number of gas passages  44  providing communication between the interior and exterior of the sleeve portion. Each of the gas passages may incorporate a filter element, e.g. of sintered metallic material held in a suitable body. When the device is in situ in a pipe, such gas passages  44  provide for escape of gas from the annular region between the pipe-engaging members and outside the sleeve portion  16 , as gas enters such region through the pressure release valves  38 ,  40 . One or more of the gas passages  44  may be closable, e.g. by a screw or press-fitting closure cap, for controlling such escape of gas. A further gas passage  46  connected to a supply pipe  48  may be provided, the pipe  48  being connectable to a gas supply for releasing further gas into the annular space aforesaid. 
         [0041]    Further features shown in  FIGS. 1 and 2  include a band of brightly-colored, preferably luminous, material provided at  50  on the exterior surface of the sleeve portion  16 . This helps in positioning of the device in relation to a region of a pipe at which welding or other work is to be carried out. The pipe-engaging members  12 ,  14  are provided with handling loops  52  for assisting the positioning of the device in relation to a pipe. 
         [0042]    Referring now to  FIGS. 3 and 4  of the drawings, these illustrate a further embodiment of a device intended for use with pipes of smaller diameter than those for which the embodiment of  FIGS. 1 and 2  is intended. 
         [0043]    The embodiment of  FIGS. 3 and 4  comprises two pipe-engaging members indicated generally at  112 ,  114 . The pipe-engaging members  112 ,  114  are the same as one another in terms of their basic construction, and each comprises a casing  118  containing an inflatable element described in greater detail hereafter. The casing  118  is stretchable material, and is able to be stretched by inflation of the inflatable element, from a starting condition in which it is shown in  FIG. 3  to a stretched condition in which it is shown, in broken lines, in  FIG. 4 , in which it firmly engages the internal surface of a pipe of appropriate diameter. 
         [0044]    In more detail, referring additionally to  FIG. 4   a  of the drawings, the pipe-engaging member  112  comprises two spaced body members  60 ,  62  which are each generally cylindrical in form, with an axial central aperture  64  enabling the two body members to be received on a pipe portion  66 . Each body member has on its exterior a circumferential groove  68 . An inflatable element  70  of tubular form and of a material such as rubber is disposed within the casing  118  which is of tubular form and made of the stretchable material as aforesaid, and the adjacent first ends of both the inflatable element  70  and casing  118  are secured to the body member  60  by being firmly held in the groove  68  by a retaining ring  72 . The respective other ends of the inflatable element  70  and casing  118  are held in like manner to the body member  62  spaced from the body member  60 . 
         [0045]    The pipe  66  is provided, in the space between the body members  60 ,  62  of the pipe-engaging member  112 , with one or more apertures as indicated at  74  so that gas from the pipe  66  can inflate the inflatable element  70 . The body member  62  is provided with a further aperture extending between opposite ends of the body member, and receiving a pressure release valve  76  by which gas under pressure can escape from the interior of the inflatable element  70 , when a predetermined pressure is exceeded. 
         [0046]    Beyond the body member  62 , the pipe  66  extends to the pipe-engaging member  114  and extends through its first body member  80  to terminate within the inflatable element (not shown) thereof. A further pipe portion  86 , shown in broken lines in  FIG. 4  extends axially through the body member  80  and also through the second body member  82  of the pipe-engaging member  114 , to permit fluid flow between opposite ends of the member  114 . 
         [0047]    The pipe  66  is provided at  90  with a fitting for connection of a supply of inert gas to the device. Two guide members  92 ,  94  each having a central through-aperture are received on the pipe  66 , one at each end of the member  112 . A further two guide members  96 ,  98  are received on the pipe  66  adjacent one end of the pipe blocking member  114  and on the pipe portion  86  adjacent the other end of the member  114 , respectively. The guide members  92  to  98  are shown as being spherical, but possibly they could be of some other configuration tapering in opposite directions lengthwise of the device, e.g. rugby ball shape. 
         [0048]    Between the body member  62  and guide member  94 , the pipe  66  carries a protective sleeve  100  of heat-resistant material. Between the guide members  94  and  96  there is a further heat-protective sleeve  102  on the pipe  66 , held in place by end ferrules  104 . Yet a further heat-protective sleeve  106  is provided on the pipe  66  between the guide member  96  and body member  80  of the pipe-engaging member  114 . 
         [0049]    The heat-resisting sleeve  102  carries an element  108  of high-visibility material as aforesaid. 
         [0050]    In use of the embodiment of device shown in  FIGS. 3 and 4 , the guide members  92  to  98  assist in moving the device along a pipe, including around bends therein possibly of relatively small radius, as long as the inflatable elements of pipe-engaging members are not inflated. When appropriately positioned, assisted if necessary by the high-visibility element  108  coming into view in the region of an opening in the pipe, or a space between adjacent pipe portions, the introduction of inert gas e.g. argon through the fitting  90  of pipe  66  causes, firstly, the inflation of the inflatable elements of the pipe-engaging members  112 ,  114 . When the pipe is firmly engaged by the members  112 ,  114 , the pressure release valve  76  releases the inert gas into the space between the members, excess gas escaping by way of the pipe portion  86 . The work on the pipe is then able to be carried out after which the gas supply can be discontinued, enabling deflation of the inflated elements and subsequent removal of the device from the pipe. 
         [0051]    When used in this specification and claims, the terms “comprises” and “comprising” and variations thereof mean that the specified features, steps or integers are included. The terms are not to be interpreted to exclude the presence of other features, steps or components. 
         [0052]    The features disclosed in the foregoing description, or the following claims, or the accompanying drawings, expressed in their specific forms or in terms of a means for performing the disclosed function, or a method or process for attaining the disclosed result, as appropriate, may, separately, or in any combination of such features, be utilized for realizing the invention in diverse forms thereof. 
         [0053]    Further modifications and alternative embodiments of various aspects of the invention will be apparent to those skilled in the art in view of this description. Accordingly, this description is to be construed as illustrative only and is for the purpose of teaching those skilled in the art the general manner of carrying out the invention. It is to be understood that the forms of the invention shown and described herein are to be taken as examples of embodiments. Elements and materials may be substituted for those illustrated and described herein, parts and processes may be reversed, and certain features of the invention may be utilized independently, all as would be apparent to one skilled in the art after having the benefit of this description of the invention. Changes may be made in the elements described herein without departing from the spirit and scope of the invention as described in the following claims.