Abstract:
A padeye tester is used for testing the condition of padeyes on underwater structures. The padeye tester has a frame having feet to engaged with an underwater structure, and a hook for engaging with a pad eye. The hook is moved under hydraulic pressure to provide a tensile force on the padeye, and the response to this tensile force indicates the padeye condition.

Description:
FIELD OF THE INVENTION 
       [0001]    The present invention relates to the testing of padeyes on subsea structures and equipment, and components thereof. 
       BACKGROUND TO THE INVENTION 
       [0002]    Subsea structures, such as those used in the oil-and-gas industries, may be positioned deep below the ocean surface, and may stay in this position for many years. Nonetheless, it may be necessary to ultimately recover the subsea structure, or components thereof, and to return it to the surface. 
         [0003]    When the item to be recovered is relatively deep, it becomes necessary to use a Remotely Operated Vehicle (ROV) in order to reach the item. With this in mind, subsea structures and components are generally equipped with a padeye, onto which a cable can be attached during deployment, and onto which an ROV can readily attach a cable for subsequent retrieval. 
         [0004]    Subsea items are subject to weakening and wear due to a number of factors, including corrosion and erosion. During retrieval of a subsea item there can often be large stress concentrations through the padeye. When the padeye has become sufficiently weakened over time, the possibility of padeye failure is greatly increased. 
         [0005]    Failure of a padeye during the early stages of item retrieval—for instance, when a cable is initially tensioned—can add significantly to the costs and times of retrieval. Failure of a padeye during retrieval, when the item is some distance from the seabed, can lead to loss of the item. 
         [0006]    The present invention has been constructed with this in mind. The present invention proposes the testing of a subsea padeye in situ, prior to the commencement of retrieval operations. The invention proposes a testing unit which is ROV deployable, and which will provide an advance indication of the fitness or otherwise of the padeye for use in retrieval operations. 
       SUMMARY OF THE INVENTION 
       [0007]    According to one aspect of the present invention there is provided a padeye tester, the padeye tester having: a frame, the frame including engagement feet for engaging with an item; and a padeye engager, the padeye engager arranged to engage with a padeye fixed to the item; the padeye engager being arranged to move relative to the frame such that a tensile force can be applied to the padeye; the padeye tester having a control means whereby the degree of tensile force applied can be controlled. 
         [0008]    Preferably, the padeye tester includes a gauge whereby any changes in the resistance to the applied force—for instance, due to yielding of the padeye—can be determined. 
         [0009]    It is preferred that the padeye engager be moved by means of hydraulic pressure. 
         [0010]    In a preferred embodiment, the frame is substantially V-shaped, with engagement feet located on both a front leg and rear leg of the frame. It is further preferred that the padeye engager be associated with a central portion of the frame, located between the front leg and the rear leg. 
         [0011]    The padeye engager may be coupled to a hydraulic cylinder located atop the central portion of the frame. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0012]    It will be convenient to further describe the invention with reference to preferred embodiments of the present invention. Other embodiments are possible, and consequently the particularity of the following discussion is not to be understood as superseding the generality of the preceding description of the invention. In the drawings: 
           [0013]      FIG. 1  is a perspective of a padeye tester in accordance with the present invention; 
           [0014]      FIG. 2  is a perspective from the other side of the padeye tester of  FIG. 1 ; 
           [0015]      FIG. 3  is a front view of the padeye tester of  FIG. 1 ; 
           [0016]      FIG. 4  is a rear view of the padeye tester of  FIG. 1 ; 
           [0017]      FIG. 5  is a first side view of the padeye tester of  FIG. 1 ; 
           [0018]      FIG. 6  is a second side view of the padeye tester of  FIG. 1 ; and 
           [0019]      FIG. 7  is a cross section through line A-A of  FIG. 1 . 
       
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
       [0020]    Referring to the Figures, there can be seen a padeye tester  10  constructed about a frame  12 . The frame  12  is generally V-shaped in cross section, with a front leg  14 , a rear leg  16 , and a central portion  18 . Each of the front leg  14  and rear leg  16  have engagement feet  20  mounted at their outer ends. The engagement feet  20  extend away from the front and rear legs  14 ,  16  respectively in a direction substantially parallel to the central portion  18 . The engagement feet  20  have contact pads  22  spaced along their length. 
         [0021]    The arrangement is such that when the contact pads  22  of the engagement feet  20  of both front leg  14  and rear leg  16  are located on an item (not shown), the central portion  18  is located directly above the item. 
         [0022]    The padeye tester  10  includes a tension applying mechanism mounted to the central portion  18  of the frame  12 . The mechanism includes a padeye engager in the form of a hook  30 , located generally beneath the central portion  18  of the frame  12 ; two lifting arms  32 ; a force transferring arm  34  and a hydraulic cylinder  36 . 
         [0023]    The hydraulic cylinder  36  is secured to an upper surface of the central portion  18  of the frame  12 . A piston rod  38  extends from an upper end of the hydraulic cylinder  36 , such that when hydraulic pressure is applied to the hydraulic cylinder  36 , the piston rod  38  is urged upwardly away from the frame  12 . 
         [0024]    The force transferring arm  34  is generally perpendicular to the hydraulic cylinder  36 , and is mounted to the piston rod  38  such that the force transferring arm  34  moves with the piston rod  38 . The force transferring arm  34  extends from one side of the frame  12  to the other, such that either end of the force transferring arm  34  extends slightly beyond the central portion  18  of the frame  12 , with the piston rod  38  being mounted in the middle of the force transferring arm  34 . 
         [0025]    The two lifting arms  32  extend from upper ends  40  located at respective ends of the force transferring arms  34  in a direction parallel to the hydraulic cylinder  36 , past respective sides of the central portion  18  of the frame  12 , to terminate at lower ends  42  beneath the central portion  18  of the frame  12 . 
         [0026]    The hook  30  is mounted between the lower ends  42  of the lifting arms  32 . The hook  30  is formed from a plate material, oriented to be in a plane generally parallel to both the force transferring arm  34  and the lifting arms  32 . The hook  30  includes a cut out portion  44  extending inwardly from a side edge of the plate material arranged, in use, to locate about a padeye. 
         [0027]    The piston rod  38 , force transferring arm  34 , lifting arms  32  and hook  30  are all rigidly connected together, and constrained to move together, such that the supply of hydraulic pressure to the hydraulic cylinder  36  results in upward movement of the hook  30 . 
         [0028]    The frame  12  includes generally trapezoidal side walls  50  which extend above the central portion  18  on either side of the hydraulic cylinder  36 , and the edges of which act as extensions of the front and rear legs  14 ,  16 . Each of the side walls  50  has a guide pad  52  mounted on its outer side. The guide pads  52  each have four guide bolts  54  projecting outwardly therefrom, which act to form side barriers to constrain a lifting arm  32  in vertical orientation. 
         [0029]    The tester  10  has a front cover  60 , a rear cover  62  and a top cover  64 . The front cover  60  extends upwardly from the front leg  12 , generally in line with the front leg  12 , and supported by front edges of the side walls  50 . The rear cover  62  similarly extends upwardly from the rear leg  14 , generally in line with the rear leg  14  and supported by rear edges of the side walls  50 . The top cover  64  extends across the top of the hydraulic cylinder  36 , between top edges of the side walls  50 . The top cover  64  is parallel to the central portion  18  of the frame  12 , and includes a central aperture through which the piston rod  38  can extend. 
         [0030]    Hydraulic lines (not shown) are located within the front cover  60  and rear cover  62 . The rear cover  62  includes ‘Quick Connect (QC)’ hydraulic couplings  70  for connection to a hydraulic fluid supply; a hydraulic isolation valve  72 ; and a hydraulic pressure gauge  74 . It will be appreciated that the QC fittings could be replaced with a ‘hot stab’ hydraulic coupling if desired. The front cover  60  includes a pressure regulating valve  76  and a flow control valve  78 . 
         [0031]    The padeye tester  10  also includes handles for ROV use. These include two side handle  80  mounted to respective side walls  50 , and a top handle  82  mounted to the upper ends  40  of the lifting arms  32 . 
         [0032]    In use, the padeye tester  10  is carried by an ROV, by means of the top handle  82 , to a subsea structure having a padeye. The ROV positions the padeye tester on the structure such that the engagement feet  20  are located on the structure, and the hook  30  is positioned next to the padeye with the cut out portion being oriented towards the padeye. The ROV then uses the top handle  82  and side handles  80  to manoeuvre the padeye tester into a position in which hook  30  is positioned about the padeye. 
         [0033]    The ROV can then open the isolation valve  72 , and apply hydraulic fluid to the hydraulic cylinder  36  by means of the QC couplings  70 . This will cause the hook  30  to lift, and tension to be applied to the padeye. 
         [0034]    The pressure gauge  74  can be used to determine that hydraulic pressure is being applied at an appropriate rate, and is increasing at an expected rate. A lack of resistance will indicate immediate failure of the padeye. 
         [0035]    Hydraulic fluid is supplied until a desired pressure is reached. At this point, the isolation valve  72  can be closed. The pressure on the gauge  74  should continue to be observed. If this pressure remains substantially constant for the duration of the test, then the padeye has not failed. A reduction in pressure during the test indicates yielding of the padeye. 
         [0036]    Following testing, the pressure can be relieved and the padeye tester  10  removed by the ROV. 
         [0037]    Modifications and variations as would be apparent to a skilled addressee are deemed to be within the scope of the present invention.