Patent Publication Number: US-2015063918-A1

Title: Methods and apparatus for arresting failures in submerged pipelines

Description:
BACKGROUND 
     This disclosure relates generally to offshore pipelines, and more specifically to methods and apparatus for responding to failures in offshore submerged pipelines. 
     In offshore pipeline installations, as the pipeline is laid on the sea floor the pipeline is subjected to significant forces and moments that can compromise the integrity of the pipeline and, in some cases, cause failures. In the event the submerged pipeline is compromised to the point of failure, water rushes into the pipeline. Such failures are commonly referred to as wet buckles. Once a wet buckle occurs the flooded pipeline is too heavy to retrieve for repair and re-installation. 
     Companies that lay the pipeline keep a fleet of compressor ships on standby while the pipeline is being laid on the sea floor in case of a failure like a wet buckle. The compressor ships are present to pump the water out of the pipeline to facilitate repair of the buckled section, by allowing the pipeline to be pulled back to the surface, to the pipelay vessel, for removal of the damaged section. After the water has been removed, sections of the damaged pipeline can be retrieved and brought to the surface and the pipelay vessel can continue laying pipe onto the sea floor. 
     Pipeline failures like wet buckles are relatively rare. As such, during installation, the fleet of compressor ships hired by the pipeline installation company is generally inactive and serves no function for the installation process unless the rare failure occurs. The cost of the compressor ships and the associated service the ships and crew provide can reach the millions of dollars. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  schematically depicts a submerged pipeline installation system including wet buckle packers in accordance with this disclosure. 
         FIG. 2  depicts an elevation view of an example wet buckle packer. 
         FIG. 3  depicts an exploded view of different components of the packer of  FIG. 2 . 
         FIG. 4A  depicts a section view of the example packer of  FIG. 2  in an unengaged state within a pipeline. 
         FIG. 4B  depicts a section view of the example packer of  FIG. 2  in an engaged state within a pipeline. 
         FIG. 5  depicts a detail view of a brake locking mechanism of the example packer of  FIG. 2 . 
         FIG. 6  depicts an example method of arresting a failure in a submerged pipeline. 
     
    
    
     DETAILED DESCRIPTION 
     In view of the foregoing costs and other inefficiencies associated with recovering from an offshore pipeline failure, examples according to this disclosure are directed to methods and apparatus for automatically responding to water invasion into the inner diameter of pipe in an offshore pipeline and rapidly deploying a sealing system that will prevent or inhibit the laid pipeline from being flooded with water. 
     A packer apparatus in accordance with this disclosure is configured to be arranged within and arrest a failure of a submerged pipeline. In one example, the packer apparatus includes an actuator disk and a seal disk in axial moveable relation with a mandrel, and a brake pivotally connected to the mandrel. The actuator disk includes a tapered outer surface. The seal disk is arranged between the actuator disk and the mandrel and includes a rim angled toward the actuator disk. The actuator disk is configured to be actuated by fluid pressure within the pipeline to move axially toward the mandrel from a first position to a second position. In the second position, the tapered outer surface of the actuator disk deflects the rim of the seal disk toward the mandrel to cause the seal disk to radially expand and engage an inner surface of the pipeline. Additionally, in the second position, the brake pivots relative to the mandrel and moves radially outward into engagement with the inner surface of the pipeline. 
     In the following examples, the apparatus for arresting pipeline wet buckles (and other pipeline failures) is referred to as a wet buckle packer. However, the apparatus could also be referred to as a plug, a shutoff pig, a baffle, or other terms connoting a device that restricts, and ideally prevents fluid flow through an annular pipeline. 
     Wet buckle packers in accordance with this disclosure provide a number of functions once actuated. Packer apparatus in accordance with this disclosure are sometimes referred to as configured to arrest a failure like a wet buckle in a submerged pipeline. Arresting a failure in a pipeline includes a number of different functions. In both dry and wet buckles, for example, the pipeline failure can include a structural failure including a buckle that causes the pipeline to at least partially collapse on itself. The structural buckle can run along the length of the pipeline unless it is arrested. In wet buckles, water also invades the inner diameter of the pipe causing the pipeline to become flooded. Packer apparatus in accordance with this disclosure can function to arrest both a structural buckle in a submerged pipeline, whether from a dry or wet buckle, and deploy a sealing system that will prevent or inhibit the laid pipeline from being flooded with water in the event of a wet buckle. Additionally, the packer deploys a braking mechanism to prevent or inhibit the packer from moving within the pipeline under the significant pressures introduced by the sea (or fresh) water entering the pipe from the wet buckle. 
     As noted above, wet buckle packers in accordance with this disclosure are configured to be automatically actuated to seal the pipeline inner diameter from ingress of water. The mechanisms for sealing and braking employed in a wet buckle packer can be actuated in a variety of ways. For example, electrical, hydraulic, or pneumatic supply lines can be run from the pipelay vessel on the surface to the packer. However, deploying supply lines from the surface downpipe to the packer will add cost and complexity to the system. The wet buckle packer could also include a power source, e.g., a battery that could be used to actuate the seal and brake mechanisms. However, the inclusion of a battery or other power source to actuate the packer will add cost and complexity to the device. In some cases, therefore, wet buckle packers are believed to be better configured to automatically actuate without the use of a power source or external actuation generator like a supply line run downpipe from the surface. As a result, while power sources or external actuation may be used in association with wet buckle packers as described herein, the examples of this disclosure are in accordance with what is believed to be the better configuration, where no such power or external source is necessary for actuation. 
     Wet buckle packers in accordance with this disclosure provide a new approach to seal and anchor a packer-type plug in place within a pipeline in the event of a wet buckle. The packers are designed to provide increased durability and to include component parts that protect against external variances. Example wet buckle packers can provide a number of advantages including, e.g., removing the high cost of air compressor standby in submerged pipeline installations and providing a simple and cost effective device for arresting failures in the pipeline. 
       FIG. 1  depicts a submerged pipeline installation system  10 . Offshore submerged pipelines can be installed in a number of ways. In general, individual pipes are transported by a cargo ship to a pipelay vessel at the pipeline installation location. The individual pipes are processed and connected to one another on the pipelay vessel and laid onto the sea floor. The pipelay vessel progressively welds individual pipes or welded pipe sections to one another to assemble the pipeline. As the pipeline is assembled the pipelay vessel moves across the surface of the water and the assembled pipeline is pulled off of the ship by the weight of the pipeline. As the pipeline is progressively pulled off of the back of the pipelay vessel it descends to the sea floor. 
     Two methods that are employed to install submerged pipelines are the “J” lay and the “S” lay. The moniker of each method represents the shape of the pipeline as it is pulled off of the pipelay vessel onto the sea floor. In a “J” lay, the pipeline is pulled off of the pipelay vessel substantially vertically to near the sea floor, where the pipeline bends to run horizontally along the floor. In an “S” lay, the pipeline is pulled off of the pipelay vessel substantially horizontally, bends vertically down toward the sea floor and then bends back horizontally away from the vessel to run along the sea floor. Although the following examples are described in the context of an “S” lay installation, wet buckle packers in accordance with this disclosure can also be employed in a “J” lay installation system or other pipeline installation methods not cover here. 
       FIG. 1  depicts a submerged pipeline installation system  10  for an “S” lay installation. In  FIG. 1 , system  10  includes pipelay vessel  12  and pipeline  14 . Pipelay vessel  12  includes production factory  16 , tensioners  18 , crane  20 , and stinger  22 . As described in more detail below, after individual pipes are transported to and loaded on pipelay vessel  12 , the pipes are conveyed into production factory  16 . Production factory  16  includes a variety of processing stations for preparing pipes and coupling individual pipes into pipe sections and ultimately assembling pipeline  14 , as will be known to persons skilled in the art. 
     Pipelay vessel  12  is shown floating in a body of water  24 . Pipelay vessel  12  utilizes crane  20  to perform heavy lifting operations, including loading pipes from a cargo ship onto the vessel. In general, individual pipes on board pipelay vessel  12  are placed on an assembly line within production factory  16  and joints of the pipes are welded into pipeline  14 . Pipeline  14  is held in tension between sea floor  26  and pipelay vessel  12  by pipeline tensioners  18  as the pipeline is lowered. As pipelay vessel  12  moves forward by pulling on a mooring system off of the bow, pipeline  14  is lowered from pipelay vessel  12  over stinger  22 . Stinger  22  is attached to and extends from the stern of pipelay vessel  12 , and provides support for pipeline  14  as it leaves pipelay vessel  12 . 
     In practice, a cargo ship transports pipe sections (sometimes referred to as stands) to pipelay vessel  12 . Crane  20  moves pipe sections from the cargo ship to pipelay vessel  12  onto cradles that form a conveyor system for moving pipe into production factory  16 . Within production factory  16 , a number of different operations are carried out to prepare and join pipe sections. For example, the pipe ends are beveled (and bevels are deburred). The pipe ends are preheated within production factory  16  and moved through a number of welding stations to join different sections with weld beads applied both to the outer and inner diameters of the sections at the joints. In some cases, a final welding station within production factory  16  applies a welded cap to the joints of pipe sections. 
     The joints of the welded pipe sections can also be tested within production factory  16 . For example, the welded joints can pass through ultrasonic testing stations that apply water to the joints as the medium to transmit the ultrasonic signals. The ultrasonic signals can be processed by a computing system and graphically displayed for inspection by an operator. 
     After testing, the joints of the welded pipe sections can be grit blasted and a field joint coating can be applied. In some installation systems, each individual pipe is subjected to this process as it is welded to pipeline  14 . In other cases, multiple pipes, e.g. two pipes in a double stand facility, are first welded together and then welded to the pipeline in the firing line onboard pipelay vessel  12 . At any rate, the assembled pipeline  14  is ultimately conveyed through tensioners  18  and over stinger  22  to be dropped off of the stern of pipelay vessel  12  to sea floor  26 . 
     As pipeline  14  is laid on sea floor  26 , suspended pipe span  28  forms a shallow “S” shape between sea floor  26  and pipelay vessel  12 . The “S” shape of suspended pipe  28  is sometimes referred to as the S-curve. Second curve  30  or the tail of the S-curve just before suspended pipe span  28  meets sea floor  26  is sometimes referred as the “sagbend.” The S-curve of pipeline  14  is controlled by stinger  22  and pipeline tensioners  18 . Increases in the curvature of pipeline  14  cause increases in the bending moment on the pipeline, and, as a result, higher stresses. High stresses on pipeline  14  and, in particular, on suspended pipe span  28  can result in buckling of the pipeline  14 . For example, a loss of tension in pipeline  14  during the pipe lay will normally cause pipeline  14  to buckle at a point along the suspended pipe span  28 . A buckle in pipeline  14  is called a wet buckle if pipeline  14  has cracked or becomes damaged in manner such that water is allowed to enter the inner diameter of the pipeline. The influx of water into the pipeline  14  greatly increases the weight of suspended pipe span  28  such that the pipe can become over stressed at a location along suspended pipe span  28 , generally near stinger  22 . In such circumstances, flooded pipeline  14  can break and drop from pipelay vessel  12  to sea floor  26 . Regardless of whether pipeline  14  breaks in the event of a wet buckle, the increased weight can prevent recovery of and repair to pipeline  14  before the water is pumped out of the pipeline. 
     Examples according to this disclosure are directed to a wet buckle packer that can be deployed within the inner diameter of pipeline  14  as it is laid on sea floor  26 . In  FIG. 1 , installation system  10  includes two wet buckle packers  32  and  34  deployed within pipeline  14 . Packer  32  is deployed along suspended pipe span  28 , while packer  34  is deployed downpipe where pipeline  14  meets sea floor  26 . Wet buckle packers  32  and  34  are deployed within pipeline  14  with a hoist line or cable (not shown). In cases where multiple wet buckle packers are deployed in series, a hoist line may be coupled between the packers. In the example of  FIG. 1 , a hoist line may be coupled to a hoist on pipelay vessel  12  to packer  32  and another line can be coupled between packers  32  and  34 . As will be apparent to persons skilled in the art, substantial benefits can be realized through an alternative configuration using only a single wet buckle packer, located generally in the position of depicted packer  34 , positioned to prevent substantial inflow of water into the already-laid portion of pipeline  14  on sea floor  26 . 
     Wet buckle packers  32  and  34  are configured to automatically respond to water invasion into the inner diameter of pipeline  14  and rapidly deploy a sealing system that will prevent the laid pipeline and pipeline above packer  32  from being flooded with sea water. For example, wet buckle packers  32  and  34  seal the inner diameter of pipeline  14  to prevent or significantly inhibit water from flooding the submerged pipeline. Additionally, wet buckle packers  32  and  34  deploy a braking mechanism to prevent or inhibit the packers from moving within pipeline  14  as a result of the pressures introduced by the sea water entering the pipe from the wet buckle. 
     In some cases one or more “piggy-back” lines may be laid from pipelay vessel  12  along with main pipeline  14 . Piggy-back lines are generally constructed from smaller diameter pipes that are assembled in a similar manner as described above with reference to pipeline  14 . The piggy-back lines are assembled in parallel with and are then coupled to pipeline  14 , e.g., with a sleeve connected to top of the main pipeline  14  in which the piggy-back lines are received. 
       FIG. 2  depicts example wet buckle packer  100 . Packer  100  includes a hoist ring  102 , a perforated cylinder  104 , an actuator disk  106 , a seal disk  108 , and a brake assembly  110 . Packer  100  is coupled to hoist line  112  by hoist ring  102 , which is connected to cylinder  104 . Actuator disk  106 , seal disk  108 , and brake assembly  110  are connected to perforated cylinder  104 . 
     Packer  100  is configured to be deployed from a pipelay vessel down a submerged pipeline via hoist line  112 . The generally cylindrical shape of packer  100  defined by the outer peripheries of perforated cylinder  104 , actuator disk  106 , seal disk  108 , and brake assembly  110  is configured to slide within the pipeline as packer  100  is deployed downpipe from the pipeline vessel. 
     Packer  100  can be deployed at a number of locations within the submerged pipeline to arrest pipeline failures like wet buckles. For example, packer  100  can be deployed along a suspended pipe span of the pipeline or further downpipe where the pipeline meets the sea floor. Wet buckle packer  100  is configured to automatically respond to water invasion into the inner diameter of the pipeline and rapidly deploy a sealing system that will prevent the laid pipeline and pipeline above packer  32  from being flooded with sea water, which is described in more detail with reference to  FIGS. 4A and 4B . 
     Hoist line  112  extends from hoist ring  102  up to, for example, a hoist machine on a pipelay vessel. In some examples, packer  100  can include hoist rings on both ends of the device to deploy multiple packers within a pipeline in space, series relation within the pipeline. Packer  100  is configured to be arranged within the pipeline such that the end including cylinder  104  faces the region of the pipeline that is at risk of a wet buckle (or other failure). Thus, in the example of  FIG. 1 , one packer could be deployed within suspended pipe span  28  closer to the surface than the likely location of the wet buckle in the sagbend of the “S” curve and another packer could be deployed within pipeline  14  on the other side of the possible wet buckle location, e.g., somewhere along sea floor  26 . 
     In this example, the packer deployed closer to the surface would be arranged within suspended pipe span  28  such that perforated cylinder  104  faces down toward the likely location of the wet buckle in the sagbend. This upper packer could include a hoist line running from the end of the device including the brake and another line running from the perforated cylinder to the lower packer. The lower packer closer to sea floor  26  would be arranged within the pipeline such that the perforated cylinder faces up toward the likely location of the wet buckle in the sagbend and the lower packer would be connected to the upper packer by the line coupled to the perforated cylinders of each device. 
       FIG. 3  depicts the components of packer  100  in more detail. Perforated cylinder  104  includes perforations  117  along the length and on the ends of cylinder  104 . Protruding from one end of cylinder  104  are posts  114 , which are disposed at different angularly disposed, circumferential positions about a longitudinal axis of packer  100 . Additionally, cylinder  104  includes central post  116  aligned with the longitudinal axis of packer  100 . 
     Actuator disk  106  is a frustoconical disk with tapered outer surface  118 . Actuator disk includes thru holes  120  and central thru hole  122 . Thru holes  120  are configured to receive posts  114  protruding from the end of cylinder  104 . Central thru hole  122  is configured to receive central post  116  of cylinder  104 . 
     As illustrated in  FIG. 3 , packer  100  also includes spindle  124 , which is configured to actuate brake assembly  110 . Spindle  124  includes end plate  126 , central shaft  128 , thru holes  130 , and central thru hole  132 . End plate  126  includes angled rim  134 . Central shaft  128  protrudes from end plate  126 . Thru holes  130  are configured to receive posts  114  protruding from the end of cylinder  104 . End plate  126  and central shaft  128  include central thru hole  132 , which is configured to receive central post  116  of cylinder  104 . 
     Seal disk  108  includes angled rim  136 , thru holes  138 , and central thru hole  140 . Thru holes  138  are configured to receive posts  114  protruding from the end of cylinder  104 . Central thru hole  140  is configured to receive central shaft  128  of spindle  124 . Seal disk  108  also includes circular ribs  141 . Ribs  141  can function to add rigidity to disk  108 . 
     Brake assembly  110  includes brake mandrel  142 , expansion wing  144 , brake clevis  146 , lever  148 , and brake pad  150 . Brake mandrel  142  includes end plate  154  with angled rim  156  and central thru hole  158 . Central thru hole  158  is configured to receive central shaft  128  of spindle  124 . Brake mandrel  142  also includes a plurality of clevises  160  disposed at different angularly disposed, circumferential positions about a longitudinal axis of packer  100 . Expansion wing  144  of brake assembly  110  includes central shaft  162  and wings  164  protruding radially outward from shaft  162 . Wings  164  are disposed at different angular positions about the circumference of central shaft  162 . Shaft  162  is configured to receive central shaft  128  of spindle  124 . Brake pad  150  has an arcuate shape and includes clevis  166  extending radially inward from the inner surface of pad  150 . Additionally, the outer surface of brake pad  150  includes a saw-tooth profile defined by a series of circumferentially extending ridges, which are configured to engage the inner surface of pipeline  170  without slipping. In many examples, the ridges will not be symmetrical, but will be configured particularly to prevent movement in the direction toward the end of packer  100  including brake assembly  110  (i.e., away from the likely location of water influx due to a wet buckle). In one example, pad  150  is manufactured from steel and, in some cases, can include carbide buttons that form the saw-tooth profile of pad  150 . 
     Packer  100  also includes a locking mechanism including ratchet pawl  152  and ratchet teeth  168  in a portion of the outer surface of central shaft  128  of spindle  124 . The configuration and function of the locking mechanism is described in detail below with reference to  FIG. 5 . 
       FIGS. 4A and 4B  depict section views of wet buckle packer  100  within pipeline  170 . In  FIG. 4A , packer  100  is unengaged with pipeline  170 . In  FIG. 4B , packer  100  is engaged with pipeline  170  to substantially seal the inner diameter of pipeline  170  from water invasion. As illustrated in the section views of  FIGS. 4A and 4B , the components of packer  100  are axially aligned along longitudinal axis  172  of packer  100 . Posts  114  and central post  116  of perforated cylinder  104  anchor actuator disk  106 , seal disk  108 , spindle  124 , and brake mandrel  142  to packer  100 . The ends of posts  114  of cylinder  104  are connected to end plate  154  of brake mandrel  142 , fixing the positions of cylinder  104  and brake mandrel  142  relative to one another. Posts  114  can be connected to end plate  154  in a variety of ways, including, e.g., using fasteners that pass through holes in plate  154  and are secured to posts  114 . Posts  114  could also be press, shrink, or heat fit into holes in plate  154  or welded to the plate. Actuator disk  106 , seal disk  108 , and spindle  124 , however, are free to move axially between cylinder  104  and mandrel  142  along posts  114  and central post  116 . 
     Actuator disk  106 , seal disk  108 , spindle  124 , and brake mandrel  142  are successively nested with one another along axis  172  of packer  100 . Tapered outer surface  118  of actuator disk  106  interfaces with angled rim  134  of spindle  124 . Angled rim  134  of spindle  124  interfaces with angled rim  136  of seal disk  108 . And angled rim  136  of seal disk  108  interfaces with angled rim  156  of brake mandrel  142 . 
     Central post  116  of cylinder  104  passes through actuator disk  106 , spindle  124 , seal disk  108 , and brake mandrel  142 . Central shaft  128  passes through seal disk  108 , brake mandrel  142 , and into shaft  162  of expansion wing  144 . 
     As noted above, brake assembly  110  includes brake mandrel  142 , expansion wing  144 , brake clevis  146 , lever  148 , and brake pad  150 . Central shaft  128  of spindle  124  is received in central shaft  162  of expansion wing  144 . Expansion wing  144  is configured to move axially as spindle  124  is pushed on by actuator disk  106 . Brake clevises  146  and levers  148  are pivotally connected between wings  164  of expansion wing  144  and clevises  160  of brake mandrel  142 . In particular, brake clevises  146  are pivotally connected to wings  164  at pivot  174  and to levers  148  at pivot  176 . Levers  148  are pivotally connected to clevises  160  of brake mandrel  142  at pivot  178  and to clevises  166  of brake pads  150  at pivot  180 . A expansion wing  144  is moved axially by spindle  124 , brake clevises  146  and levers  148  pivot and levers  148  push brake pads  150  radially outward to engage the inner surface of pipeline  170 , and to set brake assembly  110 . As illustrated in  FIGS. 4A and 4B , levers  148  include a “V,” generally boomerang shape. 
     Packer  100  is configured to be automatically actuated in the event of a wet buckle of pipeline  170 . In such an event, water invades pipeline  170  and flows through the inner diameter of the pipe toward cylinder  104 . Actuator disk  106  is configured to freely move axially relative to cylinder  104 . Without the application of an external force like the pressure produced by water in pipeline  170 , angled rim  136  of seal disk  108  maintains actuator disk  106  in relatively close proximity to cylinder  104 , as illustrated in  FIG. 4A . When the wet buckle occurs, water invading pipeline  170  passes through perforations  116  in cylinder  104  and strikes actuator disk  106 . The surface of actuator disk  106  facing cylinder  104  presents a large surface area against which the water invading pipeline  170  can strike. 
     As the pressure of the water pushes actuator disk  106  away from cylinder  104 , actuator disk  106  flattens angled rim  136  of seal disk  108  slightly and sets brake assembly  110 , as illustrated in  FIG. 4B . For example, actuator disk  106  pushes spindle  124  axially away from cylinder  104  toward brake mandrel  142 . Angled rim  134  of spindle  124  pushes against angled rim  136  of seal disk  108 , which causes angled rim  136  of seal disk  108  to flatten (or, in other words, deflect away from cylinder  104  toward mandrel  142 ). Flattening angled rim  136  of seal disk  108  causes the outer edge of seal disk  108  to move radially outward. In the engaged state illustrated in  FIG. 4B , angled rim  136  of seal disk  108  is pressed against brake mandrel  142  by spindle  124  and rim  136  is flattened to a sufficient degree to push the outer edge of seal disk  108  against the inner surface of pipeline  170 . 
     As illustrated in  FIG. 4A , the outer peripheries of both actuator disk  106  and seal disk  108  are configured to fit closely with the inner surface of pipeline  170  even when packer  100  is in an unengaged state. When packer  100  is engaged, both actuator disk  106  and seal disk  108  can function to seal pipeline  170 . For example, as described above, angled rim  134  of spindle  124  pushes against angled rim  136  of seal disk  108  to slightly flatten rim  136 . Flattening angled rim  136  of seal disk  108  causes the outer edge of seal disk  108  to move radially outward further into engagement with the inner surface of pipeline  170 . Additionally, unlike in the unengaged state of  FIG. 4A , once rim  134  of spindle  124  is pushed against rim  136  of seal disk  108 , spindle  124  prevents rim  136  from being deflected out of engagement with the inner surface of pipeline  170  by water pressure. 
     Actuator disk  106  may also function to seal pipeline  170  when packer  100  is actuated. For example, actuator disk  106  can be fabricated from an elastomer that axially compresses and radially expands under the influence of the fluid pressure from the water in pipeline  170 . Thus, in  FIG. 4B , actuator disk  106  is slightly axially compressed and the outer periphery of actuator disk  106  expands radially outward into engagement with the inner surface of pipeline  170 . 
     In some examples, packer  100  can include an actuator that either augments the effect of the water pressure on actuator disk  106  or is employed in lieu of automatic actuation by the water pressure. For example, in the event the water pressure fails to actuate the device, packer  100  could include an actuator that drives actuator disk  106  to seal pipeline  170  via seal disk  108  and set brake  122 . Example actuators that could be employed with packer  100  include a variety of mechanical and electromechanical devices that are configured to be actuated to drive actuator disk  106 . For example, actuator  128  can include a pneumatically or hydraulically actuated piston that drives actuator disk  106  with air or a hydraulic fluid supplied by supply line  130 . In another example, actuator  128  includes an electrically activated solenoid that drives actuator disk  106 . In another example, actuator  128  includes an electromagnetic piston that drives actuator disk  106  based on controlled electricity transmitted to packer  100  via supply line  130 . 
     In some examples, packer  100  can include a sensor system that detects the invasion of water into the inner diameter of pipeline  170 . In another example, the sensor system can be associated with a separate component and be communicatively coupled to packer  100 . In one example, the sensor system includes a water sensor including two spaced electrodes arranged within pipeline  118  such that water invading the pipeline would complete an electrical circuit of the sensor. In another example, a pressure sensor could be used to detect the invasion of water into the inner diameter of pipeline  118 . The sensor system communicatively coupled to packer  100  can provide a signal directly to control electronics included in an actuator of packer  100  or can transmit signals to a surface system, which, in turn, transmits control signals to an actuator via a supply line. Wet buckle detection via such a sensor system could be employed to test or verify whether packer  100  is actuated and, in some examples, could be used as a trigger to activate an actuator included in packer  100 . 
     In conjunction with axial movement of actuator disk  106  to cause seal disk  108  to engage pipeline  170 , brake assembly  110  is also deployed to prevent or substantially inhibit movement of packer  100  within pipeline  170 . For example, as the pressure of the water strikes actuator disk  106 , actuator disk  106  pushes spindle  124  axially away from cylinder  104  toward brake mandrel  142 . Central shaft  128  of spindle  124  moves expansion wing  144  axially away from cylinder  104 . Axial movement of expansion wing  144  causes wings  164  move brake clevises  146 . Brake clevises rotate about pivot  174  and pivot  176  and cause levers  148  to rotate about pivot  178 . Levers  148  rotating about pivot  178  causes levers  148  to push brake pads  150  radially outward into engagement with the inner surface of pipeline  170 . 
     Packer  100  is configured such that in the unengaged state illustrated in  FIG. 4A  at least some portions of the outer boundaries of packer  100  are offset from the inner surface of pipeline  170 . The offset distance between packer  100  and the inner surface of pipeline  170  may differ at different points along the axial length of packer  100 . For example, offset  182  between seal disk  108  and the inner surface of the pipeline  170  is different than offset  184  between brake shoes  150  and the inner surface of pipeline  170 . As noted above, the outer periphery of seal disk  106  may be configured to fit closely with the inner surface of pipeline  170  even when packer  100  is in an unengaged state. In one example, packer  100  is designed such that offset  182  is less than or equal to ⅛ inch, while offset  184  is greater than ⅛ inch. However, in other examples, offset  182  and offset  184  can be larger or smaller depending on the clearance between packer  100  and pipeline  170  necessary to allow packer  100  to be deployed through pipeline  170  and the amount of radial expansion of seal disk  108  and brake shoes  150  that is provided when actuator disk  106  moves axially away from cylinder  104 . 
     Although particular offset distances are described with reference to example packer  100 , a packer in accordance with this disclosure will be constructed with a desired dimensional relationship with the dimensions of the pipeline in which the device is to be used. In one example configuration, a radial clearance of approximately ⅛ inch will separate the sealing element of the packer and the pipeline inner surface and a radial clearance of approximately ¼ inch will separate the braking element of the packer and the pipeline inner surface. However, as will be apparent to persons skilled in the art, difference radial dimensions may be used for any size pipe, and in some cases such dimensions may be determined by other factors, such as the designed radius of bends the pipeline will experience while being installed on the sea floor, and/or the intended characteristic of the internal welds used to join the pipeline sections. 
     In some cases, it may be desirable to configured packer  100  such that offset  182  between seal disk  108  and the inner surface of the pipeline  170  is as small as possible while still allowing packer  100  to be deployed downpipe within pipeline  170 . In one example, the outer periphery of seal disk  106  is configured to abut or nearly abut the inner surface of pipeline  170  even in the unengaged state of packer  100 , as illustrated in  FIG. 4A . In practice, there may be a delay between the occurrence of a wet buckle to pipeline  170  and water striking seal disk  108  to cause packer  100  to become engaged with the inner surface of pipeline  170 . During the delay in actuation of packer  100  some water may pass through packer  100 . Reducing offset  182  between seal disk  108  and the inner surface of the pipeline  170  will reduce the amount of water that floods pipeline  170  before packer  100  is engaged and seal disk  108  substantially seals the inner diameter of the pipeline. 
     As is illustrated in  FIG. 4A , cylinder  104  is hollow and seal disk  108  and brake mandrel  142  are relatively thin-walled components. It may be desirable to design the components of packer  100  and other wet buckle packers in accordance with this disclosure in order to reduce the weight of the device. Packer  100  may be employed in relatively large pipelines. In one example, pipeline  170  has an inner diameter that is approximately equal to 40 inches. The large size of pipeline  170  necessitates a relatively large packer to seal the inner diameter of the pipeline. As such, in one example, packer  100  may weigh on the order of thousands of pounds. In such situations, removing as much material from cylinder  104 , actuator disk  106 , and other components of packer  100  can have a significant impact on the weight of the device. 
     The overall weight of packer  100  also affects the amount of load on hoist line  112  and, as a result, the amount of work required by the hoist machine operating hoist line  112 . As such, reducing the weight of packer  100  can also reduce the cost and complexity of deploying packer  100  via hoist line  112 . 
     The forces encountered by packer  100  in the event of a wet buckle of pipeline  170  may be significant. For example, at a relatively shallow depth of approximately 1500 feet below sea level, the pressures generated by a wet buckle can reach approximately 660 pounds per square inch (psi). At a depth of approximately 12,000 feet, the pressures generated by a wet buckle can reach approximately 5280 psi. In view of the range of forces potentially encountered by wet buckle packer  100 , the wall thicknesses of the components of packer  100  may need to be adjusted to withstand large forces/pressures. 
     In one example, seal disk  108  is approximately 1 inch thick. As noted, the thickness of seal disk  108  may vary depending on the range of forces encountered by the component when packer  100  is deployed to arrest a wet buckle or other failure in pipeline  170 . As noted above, seal disk  108  includes circular ribs  141 , which can function to add rigidity to disk  108 . In some cases, additional reinforcements may be added to seal disk  108 . For example, metallic stays may be added to seal disk  108 . In one example, seal disk  108  includes a plurality of either or both of radial and circumferential metallic stays that function to increase the strength and/or rigidity of seal disk  108 . Ribs  141  and additional reinforcements like radial and/or circumferential stays can be designed to accommodate radial and hoop stresses encountered by seal disk  108 . 
     Forces encountered by different portions of packer  100  may differ significantly. For example, portions of packer  100  may be partially or substantially pressure balanced because water introduced into pipeline  170  is allowed to enter parts of packer  100 . In such situations, the pressure of the water is balanced on particular portions of packer  100 . For example, water may be allowed to enter portions of packer  100  such that the water pressure is balanced on either side of a wall of cylinder  104 . In some examples, therefore, packer  100  may be designed to allow pressure balancing of some portions of the device such that the wall thicknesses of different portions of cylinder  104 , and other components of packer  100  may differ significantly depending on the amount of pressure/force encountered in the event of a wet buckle. 
     A variety of materials can be used to fabricate the components of packer  100  including, e.g., metals, plastics, elastomers, and composites. For example, cap  104 , spindle  124 , brake mandrel  142 , expansion wing  144 , brake clevises  146 , and levers  148  can be fabricated from a variety of different types of steel or aluminum. Actuator disk  106 , seal disk  108 , and brake pads  150  can be fabricated from a variety of elastomeric materials including rubber. In one example, actuator disk  106 , seal disk  108 , and/or brake pads  150  are fabricated from a nitrile rubber. At the sea floor, packer  100  may encounter temperatures as low as 32 degrees Fahrenheit (0 degrees Celsius). As such, actuator disk  106 , seal disk  108 , and brake pads  150  may need to be fabricated from elastomers that can withstand relatively low temperatures without significantly affecting the material properties of disk  108 . For example, actuator disk  106  and seal disk  108  may need to be fabricated from elastomers that can withstand relatively low temperatures without causing disks  106  and  108  to become too hard, stiff and/or brittle such that the disks are incapable of sufficiently sealing the inner diameter of pipeline  170 . The components of packer  100  can be fabricated using a variety of techniques including, e.g., machining, injection molding, casting, and other appropriate techniques for manufacturing such parts. 
     Packer  100  also includes a locking mechanism including ratchet pawl  152  and ratchet teeth  168  in a portion of the outer surface of central shaft  128  of spindle  124 .  FIG. 5  depicts a detail view of locking mechanism  200  including ratchet pawls  152  and ratchet teeth  168 . Locking mechanism  200  is configured to lock brake assembly  110  once brake pads  150  have been set against the inner surface of pipeline  170 . 
     Locking mechanism  200  includes a plurality of ratchet pawls  152 . Ratchet pawls  152  are connected to brake mandrel  142  and are disposed at different angularly disposed, circumferential positions about a longitudinal axis of packer  100 . Different numbers of pawls  152  can be employed to act in conjunction with ratchet teeth  168  to lock brake assembly  110 . For example, two ratchet pawls  152  can be arranged approximately 180 degree offsets from one another about the longitudinal axis of packer  100 . In another example, three pawls  152  can be arranged approximately 120 degree offsets from one another about the longitudinal axis of packer  100 . In another example, four pawls  152  can be arranged approximately 90 degree offsets from one another about the longitudinal axis of packer  100 . In some examples, a number of ratchet pawls  152  can be disposed at angularly disposed, circumferential positions about the longitudinal axis of packer  100  such that the pawls are unequally spaced from one another. 
     Each pawl  152  includes slot  202 . Slot  202  is sized to accommodate a spring (not shown) or other biasing mechanism that biases ratchet pawl  152  radially inward toward ratchet teeth  168  in shaft  128  of spindle  124 . As actuator disk  106  pushes spindle  124  (down in the view of  FIG. 5 ), the tapered surfaces of ratchet pawls  152  and teeth  168  in shaft  128  cause pawls  152  to pushed outward to allow spindle  124  to move in one direction one row of teeth  168  at a time. When brake assembly  110  has been radially expanded into engagement with pipeline  170  by the movement of actuator disk  106 , the blocking surfaces of pawls  152  and teeth  168  prevent spindle  124  from moving up, or, more generally, from moving in the opposite direction as the direction of the actuation of disk  106 . In this manner, locking mechanism  200  locks brake assembly  110  with brake pads  150  engaged against the inner surface of pipeline  170 . 
       FIG. 6  is a flowchart depicting an example method of arresting a wet buckle of a submerged pipeline. The method includes deploying a packer apparatus within the pipeline ( 300 ) and actuating the packer apparatus in response to water ingress into the pipeline ( 302 ). The packer apparatus can be deployed into the pipeline via a hoist line connected to a hoist machine on a pipelay vessel. In one example, the packer apparatus that is employed in conjunction with the example method of  FIG. 6  is similar to packer  100  described above. As such, in one example, packer  100  employed to carry out the method of  FIG. 6  includes actuator disk  106  and seal disk  108  in axial moveable relation with brake mandrel  142 . Actuator disk  106  includes tapered outer surface  118 . Seal disk  108  is arranged between actuator disk  106  and brake mandrel  142  and includes rim  136  angled toward actuator disk  106 . Packer  100  also includes brake assembly  110  pivotally connected to brake mandrel  142 . Actuator disk  106  can be configured to be actuated by fluid pressure within the pipeline. 
     Packer  100  is actuated in response to and as a result of water ingress into the pipeline. For example, actuating packer  100  can include moving actuator disk  106  axially toward brake mandrel  142  from a first position to a second position. Actuator disk  106  is moved from the first to the second position as a result of fluid pressure generated by the water in the pipeline. In the second position, tapered outer surface  118  of actuator disk  106  deflects rim  136  of seal disk  108  toward brake mandrel  142 , which causes seal disk  108  to radially expand and engage an inner surface of the pipeline. Additionally, in the second position, brake assembly  110  pivots relative to brake mandrel  142 , which causes brake assembly  110  to move radially outward into engagement with the inner surface of the pipeline. 
     As described above, methods of arresting wet buckles and other failures of a submerged pipeline can include deploying multiple packers within the submerged pipeline. In one example, the packers are deployed on either side (e.g. one closer to the surface and one farther from the surface and closer to the sea floor) of the likely location of the wet buckle (or other failure). In such examples, both packers can be actuated to seal the region of the pipeline between the packers and including the location of the failure. 
     As described above, the method of  FIG. 6  includes actuation of a packer apparatus in response to water ingress into a pipeline. As illustrated by the examples of packer  100 , the packer can not only be actuated in response to but also as a result of the water the water in the pipeline. In other words, the packer actuation is automatically caused by fluid pressure generated by the water invading the inner diameter of the pipeline. Thus, the example method of  FIG. 6  can be carried out with any packer apparatus that is configured to be automatically actuated by fluid pressure within a pipeline. Additional examples of such apparatus are disclosed and described in U.S. application Ser. No. ______ (Atty. Docket No. 1880.563US1), filed on Jul. ______, 2013 and entitled “METHODS AND APPARATUS FOR ARRESTING FAILURES IN SUBMERGED PIPELINES,” the entire contents of which are incorporated herein by reference. 
     Various examples have been described. These and other examples are within the scope of the following claims.