Abstract:
A joining device configured to join two facing and aligned pipeline sections presents two coupling members selectively couplable to respective pipeline sections at two respective facing flanges located at the ends of respective pipeline sections; a pulling mechanism suitable to move the coupling members towards each other in abutment against the flanges and to temporarily tighten the flanges by moving the coupling members towards each other; and a tightening mechanism suitable to definitively tighten the coupling members while the pulling mechanism keeps the flanges tight.

Description:
PRIORITY CLAIM 
       [0001]    This application is a national stage application of PCT/1B2016/050675, filed on Feb. 9, 2016, which claims the benefit of and priority to Italian Patent Application No. M12015A000177, filed on Feb. 9, 2015, the entire contents of which are each incorporated by reference herein. 
       TECHNICAL FIELD 
       [0002]    The present disclosure relates to a device for joining two aligned and facing pipeline sections. 
       BACKGROUND 
       [0003]    In general, for the purposes of the present disclosure the definition “pipeline” means a pipeline, which, in use, lies on the bed of a body of water or is partially buried in the bed of the body of water and is intended to convey gases and/or liquids, in particular hydrocarbons. A pipeline of the type identified above can extend for hundreds of kilometers, comprises sections of pipeline joined to each other aboard a vessel, and launched into the body of water from the vessel, and is laid on the bed of the body of water by the advancement of the vessel. Generally, each section of pipeline has a length of 12 meters, a relatively large diameter of between 0.2 and 1.5 meters, and comprises a steel cylinder; a protective coating, which is made of polymeric material, is placed in contact with the steel cylinder and protects the steel cylinder from corrosion; and sometimes a weighing coat of concrete or gunite is placed in contact with the protective coating. The pipelines are usually buried in the bed near the docks and in shallow waters to protect underwater pipelines from hydrodynamic stress, from temperature fluctuations, and from possible contact with foreign bodies which could jeopardize the integrity of said pipelines, including ice in extreme weather conditions. The burying of pipelines in the bed of the body of water or their covering by appropriate-sized rocky material is a widespread practice in shallow water, but is relatively hard to execute and economically unsustainable in deep waters, where the risk profile for exposed pipes may be considered acceptable in first analysis. As a result, underwater pipelines placed on the bed of a body of water in deep water may be exposed to blunt objects such as containers falling from ships in transit or accidentally pulled behind the respective craft, literally “ploughing” the bed of the body of water and possibly damaging the pipeline by lacerating the pipeline. The frequency of these incidents is relatively low, but the damage caused is relatively very high both in terms of the environmental damage which ensues, and in terms of the fact that the energy supply of many countries is closely related to the transport of hydrocarbons through underwater pipelines of the type identified above. As a result, when these incidents happen, action must be taken relatively quickly to repair the pipeline and restore the hydraulic seal and mechanical characteristics of the same. 
         [0004]    Methods have been proposed for such purpose which provide for carrying out all the repair phases in the body of water, and other methods which provide for performing certain repair phases above the body of water and other repair phases in the body of water. One repair method described in the U.S. Pat. No. 5,437,517 comprises steps of cutting a length of underwater pipeline containing the damaged area to define a first and a second section of underwater pipeline having respectively a first and a second end; joining a first coupling head to the first section of underwater pipeline in the body of water; joining a second coupling head to the second section of underwater pipeline in the body of water; laying a telescopic sleeve with a third and a fourth coupling head in the body of water and placing the telescopic sleeve between the first and second coupling head; aligning the first section of underwater pipeline, the second section of underwater pipeline and the telescopic sleeve in the body of water; adjusting the length of the telescopic sleeve in the body of water; joining the telescopic sleeve to the first and second coupling head in the body of water. Subsequently, the telescopic sleeve is locked into the final position. All the above operations are performed in the body of water using scuba equipment controlled by remote-controlled underwater vehicles (ROV: Remotely Operated Vehicle) connected to a vessel via a cord (umbilical). 
         [0005]    Other methods described in documents European Patent No. 2,430,346 and European Patent No. 2,430,347 are based on the use of telescopic sleeves and permit the repair of pipelines or merely the joining of sections of pipeline laid separately. Telescopic sleeves or other types of compensation sleeves create weakened zones of the pipeline and increase the number of operations to be performed and the complexity of the join. Still other complex methods for joining pipeline sections are disclosed in PCT Patent Application No. WO 03/040602, Great Britain Patent No. 2,038,973, and French Patent No. 2,928,987. 
       SUMMARY 
       [0006]    One of the purposes of the present disclosure is to provide a joining device which is able to join two lengths of pipeline without certain of the drawbacks of certain of the prior art. 
         [0007]    According to the present disclosure, a joining device is made for joining two facing and aligned pipeline sections, the joining device comprising two coupling members configured to be selectively coupled to respective pipeline sections in proximity of respective facing flanges located at the ends of respective pipeline sections; a pulling mechanism configured to move the coupling members towards each other so as to temporarily tighten the flanges to each other; and a tightening mechanism configured to definitively tighten the coupling members and the flanges, while the pulling mechanism maintains the flanges tight, wherein each coupling member is annular and comprises two half-rings hinged and pivotable around a hinge axis between an open position and such as to arrange the coupling members about the pipeline sections in proximity of the respective flanges, and a closed position, in which each coupling member can slide along the respective pipeline section. 
         [0008]    Thanks to the present disclosure, the pulling mechanism is made so as to exert a relatively very great force making it possible to pull into contact the sections of pipeline making them slide on the bed, and to tighten the flanges. There is no need to provide for sleeves or other lengths of pipe suitable to compensate the distance between the flanges. The compensation is provided by the elastic behaviour of the two lengths of pipeline. 
         [0009]    The tightening mechanism instead is activated when the pulling mechanism holds the flanges temporarily tight to complete the closure and make it definitive. As a result, the tightening mechanism is sized to withstand the static force exerted by sections of pipeline once the pulling mechanism is released, upon completion of the joining operation. In particular, the pulling mechanism comprises hydraulic actuators making it possible to provide a relatively very great tightening force, while the tightening mechanism comprises bolted joints. The bolted joints are releasable but their tightening is considered definitive in that their release involves active intervention of unscrewing them. 
         [0010]    The pulling mechanism makes it possible to screw the bolted joints with relatively very limited torque values during the initial phase. Relatively high screwing torque values of the bolted joints are only required in the final phase of screwing to reach the desired preload tightening of the flanges in mutual contact. 
         [0011]    A further purpose of the present is disclosure is to provide a joining method which is free of certain of the drawbacks of certain of the prior art. 
         [0012]    According to the present disclosure a method is provided for joining two facing and aligned pipeline sections, the method comprising the steps of coupling two coupling members to respective pipeline sections in proximity of respective facing flanges located at the ends of the respective pipeline sections; temporarily tightening the flanges by a pulling mechanism configured to move the coupling members towards each other; and definitively tightening the coupling members by a tightening mechanism, while the pulling mechanism keeps the flanges tight, wherein each coupling member is annular and comprises two half-rings hinged and pivotable around a hinge axis between an open position and such as to arrange the coupling members about the pipeline sections in proximity of the respective flanges, and a closed position, in which each coupling member can slide along the respective pipeline section. 
         [0013]    In particular, the joining device is able to exert a tightening force greater than 1,000,000 newtons. 
         [0014]    Additional features and advantages are described in, and will be apparent from the following Detailed Description and the figures. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0015]    Further features and advantages of the present disclosure will be evident from the description below of a non-limiting embodiment with reference to the appended drawings, wherein: 
           [0016]      FIGS. 1 and 2  are side elevation views, with parts removed for clarity, of a joining system according to the present disclosure; 
           [0017]      FIG. 3  is a perspective view on an enlarged scale, with parts removed for clarity, of a joining device for joining two sections of pipeline made according to the present disclosure; 
           [0018]      FIG. 4  is an elevation view, with parts removed for clarity and parts in cross-section, of the joining device in  FIG. 3  in a coupling step with the pipeline sections; 
           [0019]      FIG. 5  is an elevation view, with parts removed for clarity and parts in cross-section, of the joining device in  FIG. 3  coupled to the pipeline in a further operating step; and 
           [0020]      FIGS. 6 and 7  are longitudinal cross-section views, with parts removed for clarity, of two operating steps of the present disclosure. 
       
    
    
     DETAILED DESCRIPTION 
       [0021]    Referring now to the example embodiments of the present disclosure illustrated in  FIGS. 1 to 7 , with reference to  FIGS. 1 and 2 , reference numeral  1  globally denotes an underwater pipeline which, in use, is placed on the bed  2  of a body of water  3  to convey liquids or gases, in particular hydrocarbons. The underwater pipeline  1  comprises two separate sections  4  and  5  which must be joined. For simplicity of description and simplification of the drawings the bed  2  of the body of water  3  is flat, but it is understood that the underwater pipeline  1  may lie on tilted or variously rough beds. In  FIGS. 1 and 2 , in addition to the pipeline  1 , a repair and/or joining system of the underwater pipeline  1  is shown in part. The system comprises a vessel  6 ; a remotely operated underwater vehicle  7  (Remotely Operated Vehicle: ROV); two or more gantry cranes  8  suitable to be placed on the bed  2  of the body of water  3  to lift out of the bed  2  and retain the sections of pipeline  4  and  5  in a raised position from the bed  2 ; and a joining device  9 . 
         [0022]    The vessel  6  is configured to assemble underwater pipelines on board the vessel  6  itself and to launch underwater pipelines into the body of water  3 . The vessel  6  is also possibly used to flange the free ends of the pipeline sections  4  and  5  and to provide support to the joining operations of the pipeline sections  4  and  5 . In the present case illustrated, the vessel  6  comprises a floating structure and launching equipment  11 , which in this case is a launching tower that extends in a substantially vertical launching direction, is fitted in an articulated manner to the floating structure, and is configured for J-type launching to lay an underwater pipeline on the bed  2  of the body of water  3 . The launching equipment  10  comprises an upper section  11 , in which an assembly station is placed (not shown in the drawings); an intermediate section  12  in which a tensioning equipment is placed (not shown in the drawings), and a lower section  13  in which a recovery advancement device is placed (not shown in the drawings). The vessel  6  is equipped with at least one crane  14  to make a sea landing and recover the underwater vehicle  7 , the gantry cranes  8  and other equipment used in the repair of underwater pipelines  1 ; and with a winch  15 , which is supported by the launching equipment  10  and is suitable to possibly recover the pipeline sections  4  and  5  to lift them from the bed  2  of the body of water  3  and to arrange them partly inside the launching equipment  10  at the assembly station. 
         [0023]    The underwater vehicle  7  is a vehicle controlled by the vessel  6  by an umbilical  16  and comprises a frame  17 ; a float  18 ; cameras (not shown in the drawings); a group of propellers (not shown in the drawings); at least one manipulator arm  19 , and a multifunctional attachment plate  20  suitable to be coupled to respective multifunctional attachment plates of underwater equipment suitable to carry out the operations described below. Depending on the operations performed in the body of water  3  it is possible to use one or more underwater vehicles to speed up work on the underwater pipeline  1 . 
         [0024]    The gantry cranes  8  are placed astride the pipeline sections  4  and  5 . Each gantry crane  8  comprises two portal structures  21  rigidly connected together by transverse beams  22  and a group of motorized carriages  23  connected to two jaws  24  suitable to grip the pipeline sections  4  and  5 . The group of motorized carriages  23  makes it possible to move the jaws  24  along a system of Cartesian axes inside the gantry structures  21 . Each gantry crane  8  comprises a multifunctional connection (not shown in the drawings) and suitable to be connected to the multifunctional attachment  20  of the underwater vehicle  7 , which by such connection, controls the actuation of the group of motorized carriages  23  and the jaws  24 . Each portal structure  21  is provided with support plates  25  suitable to be placed so as to grip the bed  2  and define a precise position of the gantry crane  8 . 
         [0025]    With reference to  FIG. 6 , each of the pipeline sections  4  and  5  comprises a metal cylinder  26 , a protective coating (not shown in the drawings) arranged around the metal cylinder  26  and made of deformable polymeric material. The term “protective coating” includes both anti-corrosive coatings, which are relatively thin (a few millimeters) made of PP (polypropylene) or PE (polyethylene), and insulation coatings, which add to the anti-corrosion characteristics those of thermal insulation. Insulating coatings reach thicknesses of tens of millimeters and are generally made of solid PU (polyurethane) or multilayer PP (polypropylene). Sometimes, there is also a further weighing coating (not shown in the drawings) in concrete or gunite placed around the protective coating (not shown in the drawings). The pipeline sections  4  and  5  have two ends aligned and facing and two respective flanges  27  and  28  of the self-centering type. The pipeline sections  4  and  5  have respective longitudinal axes A 1  and A 2 , which are substantially aligned at the flanged ends. In the case illustrated, the flange  27  is integral with a respective sleeve  29 , which is joined to the metal cylinder  26  of the pipeline section  4 . The flange  28  is integral with a sleeve  30  joined to the metal cylinder  26  of the pipeline section  5 . The joining methods of the sleeves  29  and  30  to the respective metal cylinders comprise: welding, and plastic deformation. The flanges  27  and  28  comprise respective faces  31  and  32  configured to be placed in contact to make a hydraulic seal and define a self-centering of the pipeline sections  4  and  5 . The flanges  27  and  28  comprise respective faces  33  and  34  opposite the respective faces  31  and  32  and configured to cooperate with the joining device  9 . In the present case the flanges  27  and  28  form annular recesses along the faces  33  and  34 . 
         [0026]    With reference to the  FIGS. 3, 4, and 5 , the joining device  9  comprises a frame  35 ; a multipurpose junction plate  36 ; two coupling members  37  and  38 ; a pulling mechanism  39 ; and a tightening mechanism  40 . The pulling mechanism  39  is mounted on the coupling members  37  and  38 , and is suitable to move the coupling members  37  and  38  towards one another to place them in abutment against the flanges  27  and  28  and to tighten the flanges  27  and  28 . The tightening mechanism  40  is mounted on the coupling members  37  and  38 , and is configured to move the coupling members  27  and  28 , while the pulling mechanism  39  keeps the flanges  27  and  28  tight. 
         [0027]    The frame  35  is configured to support the coupling members  37  and  38  and comprises a longitudinal support  41  and two spacers  42  configured to be respectively coupled to the pipeline sections  4  and  5  so as to arrange the coupling members  37  and  38  at a distance determined by the two pipeline sections  4  and  5 . 
         [0028]    Each of the coupling members  37  and  38  is a ring shape, comprises two half-rings  43  pivoted and rotatable about a common hinge axis A 3  ( FIG. 5 ) between an open position such as to enable the placing of the coupling members  37  and  38  about respective pipeline sections  4  and  5  and a closed position around the respective pipeline sections  4  and  5  at the respective flanges  27  and  28 . The coupling members  37  and  38  are able to slide axially along the hinge axis A 3  which, in use, is substantially parallel to the axes A 1  and A 2  of the pipeline sections  4  and  5 . It should thus be appreciated that the coupling members  37  and  38  are configured so as to form a shaped coupling with the flanges  27  and  28 , which prevents a radial disengagement of the coupling members  37  and  38  as better illustrated in  FIG. 7 . It should be further appreciated that the coupling members  37  and  38  engage the annular recesses of the respective flanges  27  and  28  along the faces  33  and  34 . 
         [0029]    The joining device  9  comprises a third mechanism  44  configured to selectively close the half-rings  43  around the respective pipeline sections  4  and  5 . 
         [0030]    With reference to  FIG. 5 , the joining device  9  also comprises a hydraulic circuit  45  to actuate the mechanisms  39 ,  40 ,  44 , which, in particular, are of the hydraulic type. 
         [0031]    With reference to  FIG. 3 , the pulling mechanism  39  comprises a plurality of actuators  46 , which connect the coupling members  37  and  38 , are selectively activated to move the coupling members  37  and  38  towards each other, tighten the flanges  27  and  28 , and tension the two pipeline sections  4  and  5 . In the case shown, the actuators  46  are hydraulic actuators of the linear type and uniformly distributed around the coupling elements  37  and  38 . 
         [0032]    With reference to  FIG. 6 , each actuator  46  comprises a cylinder  47  mounted on a coupling member  38  and a rod  48  mounted on the other coupling member  37 . The tightening mechanism  40  comprises a plurality of bolted joints  49 , which connect the coupling members  37  and  38  and can be selectively tightened to tighten the coupling members  37  and  38  against the flanges  27  and  28 , while the pulling mechanism  39  holds the coupling members  37  and  38  tight against the flanges  27  and  28 , and the flanges  27  and  28  tightened to each other. The bolted joints  49  are evenly distributed along the coupling members  37  and  38 . Each bolted joint  49  comprises a bar  50 , which is threaded at the ends and is engaged in respective axial holes of the coupling members  37  and  38 . The threaded ends of the bar  50  protrude from opposite sides of the respective coupling members  37  and  38  and are engaged by respective nuts  51 . The tightening mechanism  40  comprises a plurality of actuators  52 , each of which is associated with a respective bolted joint  49  and has the function of screwing a nut  51 . The actuator  52  is of the rotary type operated hydraulically and is marketed by the company Hydratight. 
         [0033]    With reference to  FIGS. 4 and 5 , the coupling mechanism  44  comprises two hydraulic actuators  53  of the linear type, each of which comprises one end connected to the frame  35  and one end connected to two half-rings  43  facing each other and belonging to the two coupling members  37  and  38 . 
         [0034]    In use, once the joining device  9  has been launched in the body of water  3  and coupled to the pipeline sections  4  and  5  as shown in  FIGS. 5 and 6 , the coupling members  37  and  38  are moved together by the pulling mechanism  39  until the flanges  27  and  28  touch each other as shown in  FIG. 7 . At this stage, any small alignment errors of the axes A 1  and A 2  of the respective pipeline sections  4  and  5  are corrected thanks to the flanges  27  and  28  of the self-centering type. The force exerted by the pulling mechanism  39  is relatively very great and permits the elastic deformation of the pipeline sections  4  and  5  to compensate for the distance, generally a few centimeters, between the flanges  27  and  28 . This tightening force is transmitted from the vessel  6  to the flanges  27  and  28  via the umbilical  16 , the underwater vehicle  7 , and the pulling mechanism  39 , according to the diagram shown in  FIG. 2 . However, once the underwater vehicle  7  is uncoupled from the joining device  9 , the tightening force is released. Before releasing the tightening force, the tightening mechanism  40  is actuated to tighten the flanges  27  and  28  and the coupling members  37  and  38  in the tightened position. Once the flanges  27  and  28  and the coupling members  37  and  38  have been tightened by tightening the nuts  51 , the joining of the pipeline sections  4  and  5  is completed and the underwater vehicle  7  is uncoupled from the joining device  9 . 
         [0035]    It is evident that variations may be made to the embodiment described of the present disclosure while remaining within the scope of the following claims. Accordingly, various changes and modifications to the presently disclosed embodiments will be apparent to those skilled in the art. Such changes and modifications can be made without departing from the spirit and scope of the present subject matter and without diminishing its intended advantages. It is therefore intended that such changes and modifications be covered by the appended claims.