Patent Publication Number: US-2015063921-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 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 a first spindle in axial moveable relation with a second spindle. The first spindle includes a pressure plate disposed adjacent a first end of the packer apparatus. The second spindle includes a base plate disposed adjacent a second end of the packer apparatus. A seal plate is disposed between the pressure and base plates. A brake is disposed between the pressure and seal plates. An elastomeric expansion boot is disposed between the seal and base plates. The pressure plate is configured to be actuated by fluid pressure within the pipeline to move the first spindle axially toward the second spindle from a first position to a second position. In the second position, the first spindle causes: the brake to move radially outward into engagement with an inner surface of the pipeline; and the seal plate to move axially toward the base plate to axially compress and radially expand the expansion boot 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. The packer seals the inner diameter of the pipeline to prevent or significantly inhibit water from flooding the submerged pipeline. 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 covered 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 a 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 end cap  104 , a first and second spindles  106  and  108 , a seal plate  110 , an elastomeric expansion boot  112 , and a brake assembly  114 . Packer  100  is coupled to hoist line  113  by hoist ring  102 , which is connected to cap  104 . 
     Packer  100  is configured to be deployed from a pipelay vessel down a submerged pipeline via hoist line  113 . The generally cylindrical shape of packer  100  defined by the outer peripheries of cap  104 , second spindle  108 , seal plate  110 , and expansion boot  112  are 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 from being flooded with sea water, which is described in more detail with reference to  FIGS. 4A and 4B . 
     Hoist line  113  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 cap  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 cap  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 second spindle  108  and another line running from perforated cap  104  to the lower packer. The lower packer closer to sea floor  26  would be arranged within the pipeline such that cap  104  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 caps of each device. 
       FIG. 3  depicts the components of packer  100  in an exploded view to illustrate the components in greater detail. Perforated cap  104  includes pie-piece shaped perforations  116 . Cap  104  includes a frustoconical shape including two generally flat ends and a conical side extending between the ends. The interior of perforated cap  104  is hollow and sized to receive a portion of first spindle  106 . Perforated end cap  104  also includes central thru hole  117 . 
     First spindle  106  is configured to cause seal plate  110  to axially compress and radially expand expansion boot  112  and to actuate brake assembly  114 . First spindle  106  includes end plate  118 , central shaft  120 , and bore  132 . Central shaft  120  protrudes from end plate  118 . 
     Second spindle  108  includes end plate  124  and central shaft  126 , which protrudes from end plate  124 . End plate  124  includes a tapered outer rim  128 . End plate  124  of second spindle  108  generally defines one end of packer apparatus  100 , while perforated cap  104  defines the opposite end of the device. 
     Seal plate  110  includes angled rim  130  and central thru hole  132 . Expansion boot  112  includes rounded edges  134  and central thru hole  136 . 
     Brake assembly  114  includes brake mandrel  142 , expansion wing  144 , a plurality of brake clevises  146 , levers  148 , and brake pads  150  (only one of each is illustrated in  FIG. 3 ). Brake mandrel  142  includes end plate  154  with central thru hole  158 . Central thru hole  158  is configured to receive central shaft  120  of first spindle  106 . 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  122  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  120  of first spindle  106 . Brake pad  150  has an arcuate shape and includes clevis  166  extending radially inward from the inner surface of pad  150 . Lever  148  includes a “V,” generally boomerang shape. 
     Packer  100  also includes packer mandrel  168  and seal actuator  170 , which is configured to be axially aligned with and at least partially arranged within packer mandrel  168 . Packer mandrel  168  includes a plurality of fingers  172 , which are circumferentially disposed about a longitudinal axis of packer  100  and extend axially from end plate  174 . Fingers  172  are offset from one another defining a plurality of axially extending slots  176 . End plate  174  includes a number of arcuate slots  178 . 
     Seal actuator  170  includes a plurality of arcuate flanges  180 , which are circumferentially disposed about a longitudinal axis of packer  100  and extend axially from plate  182 . Seal actuator  170  also includes central shaft  184  extending axially from plate  182  in the opposite direction from arcuate flanges  180 . Central shaft  184  is supported and strengthened by buttresses  186 , which are circumferentially disposed about shaft  184 . Arcuate slots  178  of packer mandrel  168  are configured to receive arcuate flanges  180  of seal actuator  170 . 
     Packer  100  also includes two lock washers  188  and  190 , which are configured to lock packer in an engaged state with expansion boot  112  and brake assembly  114  engaging the inner surface of pipeline  171 . Lock washers  188  and  190  include respective central apertures  192  and  194 . Central aperture  192  of lock washer  188  is configured to receive central shaft  120  of first spindle  106 . Central aperture  194  of lock washer  190  is configured to receive central shaft  126  of second spindle  108 . 
       FIGS. 4A and 4B  depict section views of wet buckle packer  100  within pipeline  171 . In  FIG. 4A , packer  100  is unengaged with pipeline  171 . In  FIG. 4B , packer  100  is engaged with pipeline  171  to substantially seal the inner diameter of pipeline  171  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  200  of packer  100 . The components of packer  100  are generally axially aligned by central shaft  126  of second spindle  108  and central shaft  120  of first spindle  106 . Central shaft  126  of second spindle  108  is received in each of central hole  136  of expansion boot  112 , central hole  132  of seal plate  110 , central aperture  194  of lock washer  190 , shaft  184  of seal actuator  184 , bore  122  of first spindle  106 , and central hole  117  of perforated cap  104 . Central shaft  120  of first spindle  106 , which receives central shaft  126 , is received in central hole  158  of brake mandrel  142 , shaft  162  of expansion wing  144 , and central aperture  192  of lock washer  188 . 
     Perforated cap  104  is connected to brake mandrel  142 , which is connected to fingers  172  of packer mandrel  168 . Perforated cap  104 , brake mandrel  142 , and fingers  172  of packer mandrel  168  can be connected by a variety of mechanisms including, e.g., fasteners or welds. Cap  104 , brake mandrel  142 , and packer mandrel  168  can be connected to one another by a variety of mechanisms, including, e.g., using fasteners or welding the components to one another. End plate  118  of first spindle  106  is received within cap  104 . Central shaft  120  extends through central hole  158  of brake mandrel  142  and shaft  162  of expansion wing  144  to abut shaft  184  of seal actuator  170 . Seal actuator  170  is partially received within packer mandrel  168 . Arcuate flanges  180  of seal actuator  170  pass through arcuate slots  178  of packer mandrel  168 . 
     Expansion boot  112  is a hollow elastomeric boot including central hole  136  that receives central shaft  126  of second spindle  108 . In another example, expansion boot  112  is not hollow. Expansion boot  112  is arranged between end plate  124  of second spindle  108  and seal plate  110 . As end plate  118  of first spindle  106  moves axially toward end plate  124  of second spindle  108 , expansion boot  112  is compressed axially. As expansion boot  112  is compressed axially, boot  112  also radially expands into engagement with an inner surface of pipeline  171 . Rounded edges  134  of expansion boot  112  and angled rims  128  and  130  of end plate  124  and seal plate  110 , respectively, may be configured to bias expansion boot  112  to move radially outward, instead of inward, when boot  112  is compressed axially between seal plate  110  and end plate  124 . 
     As noted above, brake assembly  114  includes brake mandrel  142 , expansion wing  144 , brake clevises  146 , levers  148 , and brake pads  150 . Central shaft  120  of first spindle  106  is received in central shaft  162  of expansion wing  144 . Expansion wing  144  is configured to move axially with first spindle  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  202  and to levers  148  at pivot  204 . Levers  148  are pivotally connected to clevises  160  of brake mandrel  142  at pivot  206  and to clevises  166  of brake pads  150  at pivot  208 . As expansion wing  144  is moved axially by first spindle  106 , brake clevises  146  and levers  148  pivot and levers  148  push brake pads  150  radially outward to engage the inner surface of pipeline  171 , and to set brake assembly  114 . 
     Packer  100  is configured to be automatically actuated in the event of a wet buckle of pipeline  171 . In such an event, water invades pipeline  171  and flows through the inner diameter of the pipe toward cap  104 . End plate  118  of first spindle  106  is configured to move axially within cap  104 . Without the application of an external force like the pressure produced by water in pipeline  171 , end plate  118  is positioned toward the end of perforated cap  104  to which hoist ring  102  is connected, as illustrated in  FIG. 4A . When the wet buckle occurs, water invading pipeline  171  passes through perforations  116  in cap  104  and strikes end plate  118  of first spindle  106 , which moves end plate  118  axially toward end plate  124  of second spindle  108 , i.e. toward the opposite end of packer  100 . The surface of end plate  118  presents a large surface area against which the water invading pipeline  171  can strike. 
     As the pressure of the water pushes end plate  118  of first spindle  106  axially toward end plate  124  of second spindle  108 , central shaft  120  of first spindle  106  moves axially through hole  158  of brake mandrel  142  and strikes shaft  184  of seal actuator  170 . Central shaft  120  pushes seal actuator  170  against seal plate  110 . In particular, central shaft  120  pushes arcuate flanges  180  of seal actuator  170  through arcuate slots  178  of packer mandrel  168 . Arcuate flanges  180  push seal plate  110  toward end plate  124  of second spindle  108 . As seal plate  110  moves axially toward end plate  124  of second spindle  108 , expansion boot  112  is compressed axially between disk  110  and plate  124 . As expansion boot  112  is compressed axially, boot  112  also radially expands into engagement with an inner surface of pipeline  171 . In the radially expanded state illustrated in  FIG. 4B , expansion boot  112  are configured to substantially seal pipeline  171  and thereby arrest or mitigate the wet buckle in the pipeline. 
     In some examples, packer  100  can include an actuator that either augments the effect of the water pressure on end plate  118  of first spindle  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 first spindle  106  to seal pipeline  171  and set brake assembly  114 . 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 first spindle  106 . For example, the actuator can include a pneumatically or hydraulically actuated piston that drives actuator disk  106  with air or a hydraulic fluid supplied by a supply line connected to packer  100 . In another example, the actuator includes an electrically activated solenoid that drives first spindle  106 . In another example, the actuator includes an electromagnetic piston that drives actuator disk  106  based on controlled electricity transmitted to packer  100  via the supply line. 
     In some examples, packer  100  can include a sensor system that detects the invasion of water into the inner diameter of pipeline  171 . 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  171  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 first spindle  106  to cause expansion boot  112  to engage pipeline  171 , brake assembly  114  is also deployed to prevent or substantially inhibit movement of packer  100  within pipeline  171 . For example, as the pressure of the water strikes end plate of first spindle  106 , central shaft  120  moves axially through central hole  158  of brake mandrel  142 . Central shaft  120  of first spindle  106  moves expansion wing  144  axially away from cap  104 . Axial movement of expansion wing  144  causes wings  164  to move brake clevises  146 . Brake clevises  146  rotate about pivot  202  and pivot  204  and cause levers  148  to rotate about pivot  206 . Levers  148  rotating about pivot  206  causes levers  148  to push brake pads  150  radially outward into engagement with the inner surface of pipeline  171 . The outer surfaces of brake pads  150  include a saw-tooth profile defined by a series of circumferentially extending ridges (see  FIG. 2 ), which are configured to engage the inner surface of pipeline  171  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 second spindle  108  (i.e., away from the likely location of water influx due to a wet buckle). In one example, pads  150  are manufactured from steel and, in some cases, can include carbide buttons that form the saw-tooth profile of pads  150 . 
     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  171 . The offset distance between packer  100  and the inner surface of pipeline  171  may differ at different points along the axial length of packer  100 . For example, offset  210  between expansion boot  112  and the inner surface of the pipeline  171  is different than offset  212  between brake pads  150  and the inner surface of pipeline  171 . The outer periphery of end plate  124  of second spindle  108 , expansion boot  112 , and seal plate  110  may be configured to fit closely with the inner surface of pipeline  171  even when packer  100  is in an unengaged state. In one example, packer  100  is designed such that offset  210  is less than or equal to ⅛ inch, while offset  212  is greater than ⅛ inch. However, in other examples, offset  210  and offset  212  can be larger or smaller depending on the clearance between packer  100  and pipeline  171  necessary to allow packer  100  to be deployed through pipeline  171  and the amount of radial expansion of seal plate  110  and brake pads  150  that is provided when first spindle  106  moves axially toward second spindle  108 . 
     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  210  between expansion boot  112  and the inner surface of the pipeline  171  is as small as possible while still allowing packer  100  to be deployed downpipe within pipeline  171 . In one example, the outer periphery of expansion boot  112  is configured to abut or nearly abut the inner surface of pipeline  171  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  171  and water striking end plate  118  of first spindle  106  to cause packer  100  to become engaged with the inner surface of pipeline  171 . During the delay in actuation of packer  100  some water may pass through packer  100 . Reducing offset  210  between expansion boot  112  and the inner surface of the pipeline  171  will reduce the amount of water that floods pipeline  171  before packer  100  is engaged and expansion boot  112  substantially seals the inner diameter of the pipeline. 
     As is illustrated in  FIG. 4A , cap  104  and expansion boot  112  are hollow and brake mandrel  142 , packer mandrel  168 , and seal actuator  170  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  171  has an inner diameter that is approximately equal to 40 inches. The large size of pipeline  171  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 cap  104 , expansion boot  112 , brake mandrel  142 , packer mandrel  168 , seal actuator  170 , 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  113  and, as a result, the amount of work required by the hoist machine operating hoist line  113 . As such, reducing the weight of packer  100  can also reduce the cost and complexity of deploying packer  100  via hoist line  113 . 
     The forces encountered by packer  100  in the event of a wet buckle of pipeline  171  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. 
     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  171  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 one or more of cap  104 , seal plate  110 , brake mandrel  142 , packer mandrel  168 , and seal actuator  170 . In one example, a seal is provided between the outer diameter on first spindle  106  and the inner diameter of cap  104 . In such a case, the only components of packer  100  substantially affected by pressure differentials will be cap  104 , first spindle  106  and expansion boot  112 . 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 cap  104 , seal plate  110 , brake mandrel  142 , packer mandrel  168 , seal actuator  170 , 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 , first spindle  106 , second spindle  108 , seal plate  110 , brake mandrel  142 , expansion wing  144 , brake clevises  146 , levers  148 , packer mandrel  168 , brake pads  150 , and seal actuator  170  can be fabricated from a variety of different types of steel or aluminum. Expansion boot  112  can be fabricated from a variety of elastomeric materials including rubber. In one example, expansion boot  112  is 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, expansion boot  112  may need to be fabricated from elastomers that can withstand relatively low temperatures without significantly affecting the material properties of disk  108 . For example, expansion boot  112  may need to be fabricated from elastomers that can withstand relatively low temperatures without causing boot  112  to become too hard, stiff and/or brittle such that the disks are incapable of sufficiently sealing the inner diameter of pipeline  171 . 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 lock washer  188  surrounding central shaft  120  of first spindle  106  and lock washer  190  surrounding central shaft  126  of second spindle  108 . Both lock washers  188  and  190  allow movement in one direction, while preventing movement in the opposite direction. For example, lock washer  188  is disposed such that first spindle  106  including central shaft  120  can move axially toward second spindle  108 , but prevents first spindle  106  from moving away from second spindle  108 . Lock washer  190  is coupled to seal plate  110 . Lock washer  190  is disposed such that washer  190  can be pushed toward second spindle  108  along with seal plate  110 , but prevents seal plate  110  from moving away from second spindle  108  after packer  100  has been engaged. A rack and pawl ratchet system may also be employed. An example ratchet mechanism that could be configured for use with packer  100  is disclosed and described in described in U.S. application Ser. No. ______ (Atty. Docket No. 1880.517US1), filed July ______, 2013 and entitled “METHODS AND APPARATUS FOR ARRESTING FAILURES IN SUBMERGED PIPELINES,” the entire contents of which are incorporated herein by reference. 
       FIG. 5  is a flowchart depicting an example method of arresting a failure 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. 5  is similar to packer  100  described above. As such, in one example, packer  100  employed to carry out the method of  FIG. 5  includes first spindle  106  in axial moveable relation with second spindle  108 . First spindle  106  includes pressure plate  118  disposed adjacent a first end of the packer  100  including cap  104 . Second spindle  108  includes shaft  126  and base plate  124  disposed adjacent a second end of packer  100  opposite the first end. Packer  100  also includes seal plate  110  disposed between pressure and base plates  118  and  124 , respectively, brake assembly  114  disposed between pressure and seal plates  118  and  110 , respectively, and elastomeric expansion boot  112  disposed between seal and base plates  110  and  124 , respectively. 
     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 first spindle  106  axially toward second spindle  108  from a first position to a second position. First spindle  106  is moved from the first to the second position as a result of fluid pressure generated by the water in the pipeline. The fluid pressure of the water in the pipeline acts to push pressure plate  118  of first spindle  106 , which drives spindle  106  including central shaft  120  axially toward base plate  124  of second spindle  108 . In the second position, central shaft  120  of first spindle  106  drives seal actuator  170  against seal plate  110 . Seal plate  110  is moved axially toward base plate  124  to axially compress and radially expand expansion boot  112  into engagement with the inner surface of the pipeline. Additionally, in the second position, brake assembly  114  pivots relative to brake mandrel  142 , which causes brake assembly  114  to move radially outward into engagement with the inner surface of the pipeline. 
     As described above, methods of arresting 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. 5  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 pipeline. Thus, the example method of  FIG. 5  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. 1880.517US1), filed on July ______, 2013, U.S. application Ser. No. ______ (Atty. Docket No. 1880.519US1), filed on July ______, 2013, and U.S. application Ser. No. ______ (Atty. Docket No. 1880.563US1), filed on July ______, 2013, all of which are entitled “METHODS AND APPARATUS FOR ARRESTING FAILURES IN SUBMERGED PIPELINES,” and the entire contents of all of which are incorporated herein by reference. 
     Various examples have been described. These and other examples are within the scope of the following claims.