Patent Publication Number: US-2015063914-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 spindle, a first end cap, a seal plate, a mandrel, a brake, and an elastomeric expansion boot. The spindle includes a pressure plate disposed adjacent a first end of the packer apparatus. The first end cap defines the second end of the packer apparatus. The seal plate is disposed between the pressure plate and the first end cap. The mandrel and brake are disposed between the pressure and seal plates. The mandrel includes a tapered outer surface and the brake includes a tapered inner surface abutting the tapered inner surface of the mandrel. The expansion boot is disposed between the seal plate and the first end cap. The pressure plate is configured to be actuated by fluid pressure within the pipeline to move the spindle axially toward the first end cap from a first position to a second position. In the second position, the spindle causes: the expansion boot to compress axially between the seal plate and the first end cap and expand radially into engagement with an inner surface of the pipeline; and the tapered inner surface of the brake to move axially along the tapered outer surface of the mandrel to cause the brake to move 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 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 spindle  106 , a base cap  108 , a seal plate  110 , a packer mandrel  112 , an elastomeric expansion boot  114 , and a brake assembly  116 . 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 . Packer  100  can be lowered into an already submerged pipeline or can be lowered along with a particular section of the pipeline as it is dropped to the sea floor. The generally cylindrical shape of packer  100  defined by the outer peripheries of end cap  104 , spindle  106 , base cap  108 , seal plate  110 , elastomeric expansion boot  114 , and brake assembly  116  are configured to slide within the pipeline as packer  100  is deployed downpipe from the pipeline vessel. Additionally, end cap  104 , base cap  108 , and brake assembly  116  each include a number of freely rotating wheels  118 ,  120 , and  122 , respectively, which are distributed around the outer circumference of each of the components. Wheels  118 ,  120 , and  122  facilitate travel of packer  100  through the submerged pipeline as packer  100  is lowered from the pipelay vessel and as otherwise may be needed during the pipe laying process. 
     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 spaced, 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 likely 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 base cap  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 some components of packer  100  in an exploded view to illustrate the components in greater detail. Perforated cap  104  includes pie-piece shaped perforations  130 . The interior of perforated cap  104  is hollow and sized to receive a portion of spindle  106 . Perforated end cap  104  also includes central thru hole  132 . 
     Spindle  106  is configured to cause seal plate  110  to axially compress and radially expand expansion boot  114  and to actuate brake assembly  116 . Spindle  106  includes end plate  134 , central shaft  136 , and bore  138 . Central shaft  136  protrudes from end plate  134 . End plate  134  includes a number of circumferential grooves, including groove  140  and another groove that is configured to receive O-ring  142 . O-ring  142  or other similarly functioning seals can be employed to provide a seal between the outer surface of end plate  134  and the inner surface of end cap  104 . 
     Base cap  108  includes a generally cylindrical main body  144  and central shaft  146  extending axially from body  144 . Wheels  120  are rotatably coupled to main body  144  of base cap  108 . Base cap  108  also includes central thru hole  148  in central shaft  146 . 
     Seal plate  110  includes rim portion  150  and hub portion  152 . Additionally, seal plate  110  includes central thru hole  154  in hub  152 . 
     Packer mandrel  112  includes a cylindrical portion  154  and a conical portion  156 . Cylindrical portion  154  includes a plurality of axially extending flanges  158 . Conical portion  156  includes a tapered outer surface and a plurality of “T” shaped grooves  160 , which are inscribed in and distributed evenly around the outer surface of conical portion  156 . Packer mandrel  112  also includes bore  162 . The base of bore  162  includes a plurality of thru holes  164 . 
     Brake assembly  116  includes brake mandrel  166  and brake pads  168 , only one of which is illustrated in  FIG. 3 . Brake mandrel  166  includes a cup-shaped body  168 , a plurality of clevises  170 , and a plurality of posts  172 . One end of body  168  includes a plurality of apertures  174  and central thru hole  176 . Wheels  122  are rotatably connected to body  168 . Clevises  170  and posts  172  extend axially from and are connected to body  168 . In one example, clevises  170  and/or posts  172  are fabricated separately from and connected to body  168 , e.g., by fasteners, welding, or another mechanism. In another example, body  168 , clevises  170 , and posts  172  are fabricated as a single, integral component. Each of clevises  170  includes a “T” shaped slot  178 . 
     Brake pad  168  includes a curved outer surface  180  and a tapered inner surface  182 . Outer surface  180  includes a saw-tooth profile defined by a series of circumferentially extending ridges (see also  FIG. 2 ). Tapered inner surface  182  includes a conical surface that is configured to match and slide along the tapered outer surface of conical portion  156  of packer mandrel  112 . Pad  168  also includes “T” shaped tongues  184  and  186 . Tongue  184  is configured to be received in grooves  160  in conical portion  156  of packer mandrel  112 . Tongue  186  is configured to be received in slot  178  in a clevis  170  of brake mandrel  166 . 
       FIGS. 4A and 4B  depict section views of wet buckle packer  100  within pipeline  200 . In  FIG. 4A , packer  100  is unengaged with pipeline  200 . In  FIG. 4B , packer  100  is engaged with pipeline  200  to substantially seal the inner diameter of pipeline  200  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  202  of packer  100 . Packer includes mounting shafts  204  and  206  by which the components of packer  100  are coupled and axially aligned. Mounting shaft  204  is connected to packer mandrel  112  within conical bore  208  and is received in central hole  154  of seal plate and central hole  148  of base cap  108 . Mounting shaft  206  is connected to packer mandrel  112  within cylindrical bore  162  and is received in bore  138  of spindle  106 . Spindle  106  is arranged and moves axially within end cap  104 . Additionally, shaft  136  of spindle  106  is received in central hole  176  of brake mandrel  166 . 
     Mounting shafts  204  and  206  can be connected to packer mandrel  112  by fasteners, welding, or other mechanisms. Additionally, packer mandrel  112  can be fabricated with mounting shafts  204  and  206  integral with the mandrel. The end of mounting shaft  204  opposite the connection with packer mandrel  112  is connected to base cap  108  by, e.g., a threaded connection including a nut as illustrated in  FIGS. 4A and 4B  or another appropriate mechanism. 
     End cap  104 , base cap  108 , and packer mandrel  112  remain in a fixed position relative to other components of packer  100  in both the unengaged and engaged states illustrated in  FIGS. 4A and 4B , respectively. Spindle  106 , seal plate  110 , expansion boot  114 , and brake assembly  116 , on the other hand, are all configured to change position when packer  100  is actuated. 
     End cap  104  is connected to one end of packer mandrel  112 . Base cap  108  is connected adjacent the opposite end of packer mandrel  112  via mounting shaft  204  connected through hole  148  in shaft  146  of base cap  108 . 
     Seal plate  110  is disposed between packer mandrel  112  and base cap  108 . Hub  152  of seal plate  110  receives shaft  146  of base cap  108 . Additionally, hub  152  is arranged and axially moveable within conical bore  208  of packer mandrel  112 . As noted above, base cap  108 , seal plate  110 , and packer mandrel  112  are axially aligned by mounting shaft  204 . 
     Expansion boot  114  includes two annular elastomeric boots separated by a spacer  210 . Expansion boot  114  includes a central hole, which receives central shaft  146  of base cap  108 . Body  144  and shaft  146  of base cap  108  form shoulder  210 . Expansion boot  114  is arranged between rim  150  of seal plate  110  and shoulder  210  of base cape  108 . Spindle  106  is configured to move axially toward base cap  108 . As spindle  106  moves toward base cape  108 , spindle  106  causes rim  150  of seal plate  110  to move closer to shoulder  210  of base cap, which compresses expansion boot  114  axially. As expansion boot  114  is compressed axially, boot  114  also radially expands into engagement with an inner surface of pipeline  200 . 
     As noted above, expansion boot  114  includes two annular elastomeric boots separated by spacer  210 . However, in other examples, expansion boot  114  can include one or more than two elastomeric elements. Spacer  210  can be a Teflon, brass, rubber, or other appropriate type of spacer element or elements interposed between the elastomeric boots of expansion boot  114 . Employing multiple elastomeric boots allows each boot of expansion boot  114  to include different Durometers. Employing multiple boots with multiple, different Durometers can allow packer  100  to be used in a range of different depths and different temperatures. 
     Brake assembly  116  includes brake mandrel  166  and brake pads  168 . Each brake pad includes tapered inner surface  180 . Tapered inner surface  180  is configured to match and slide along a tapered outer surface  212  formed by conical portion  156  of packer mandrel  112 . Axial and radial translation of brake pads  168  are guided by tapered inner surface  182  of pads  168  and tapered outer surface  212  of packer mandrel  112 . Pads  168  can also be generally fixed and located in the circumferential direction by “T” shaped tongues  186 , which cooperate with and are received by corresponding “T” shaped grooves  160  in tapered outer surface  212 . Grooves  160  are inscribed in outer surface  212  of packer mandrel  120  at different angularly disposed, circumferential positions around longitudinal axis  202  of packer  100 . 
     As spindle  106  moves axially toward base cap  108 , shaft  136  of spindle  106  drives brake mandrel  166  axially toward seal plate  110 . Axial movement of brake mandrel  166  drives brake pad  168  toward seal plate  110 . As brake pad  168  moves axially toward seal plate  110 , pad  168  is also driven radially outward by the interaction between tapered inner surface  182  of pad  168  and tapered outer surface  212  of conical portion  156  of packer mandrel  112 . To accommodate the radially changing position of brake pad  168  and the radially fixed position of brake mandrel  166 , “T” shaped tongue  184  of pad  168  is configured to slide in slot  178  of clevis  170  of brake mandrel  166  as brake assembly  116  is driven axially toward seal plate  110 . 
     As tapered inner surface  182  of pad  168  slides along tapered outer surface  212  of packer mandrel  112  to drive pad  168  radially outward, brake pad  168  is pushed radially outward into engagement with the inner surface of pipeline  200 . Outer surface  180  of brake pad  168  includes a saw-tooth profile defined by a series of circumferentially extending ridges, which are configured to engage the inner surface of pipeline  128  without slipping. In many examples, the ridges will not be symmetrical, but will be configured particularly to prevent movement in the direction toward base cap  108  (i.e., away from the likely location of water influx due to a wet buckle). In one example, pad  168  is manufactured from steel and, in some cases, can include carbide buttons that form the saw-tooth profile of pad  168 . 
     Packer  100  is configured to be automatically actuated in the event of a wet buckle of pipeline  200 . In such an event, water invades pipeline  200  and flows through the pipe toward end cap  104 . Pressure plate  134  of spindle  106  is configured to move axially within cap  104 . Pressure plate  134  can be sealed within end cap  104 , e.g., by O-ring  142 . Additional seals between pressure plate  134  and end cap  104  can also be provided, including, e.g., one or more O-rings received in grooves in the inner surface of end cap  104 . Without the application of an external force like the pressure produced by water in pipeline  200 , pressure plate  134  is positioned toward the end of end cap  104  to which hoist ring  102  is connected, as illustrated in  FIG. 4A . When the wet buckle occurs, water invading pipeline  200  passes through perforations  130  in cap  104  and strikes pressure plate  134  of spindle  106 , which moves pressure plate  134  axially base cap  108 , i.e. toward the opposite end of packer  100 . The surface of pressure plate  134  presents a large surface area against which the water invading pipeline  200  can strike. 
     As the pressure of the water pushes pressure plate  134  of spindle  106  axially toward base cap  108 , central shaft  136  of spindle  106  moves axially drives brake mandrel  166  axially toward seal plate  110 . Posts  172  of brake mandrel  166  push seal plate  110 . In particular, brake mandrel  166  moves axially toward seal plate  110 , which causes brake mandrel  166  to move relative to packer mandrel  112 . As brake mandrel  166  moves, flanges  158  of packer mandrel  112  slide through apertures  174  in brake mandrel  166 . Additionally, posts  172  slide through holes  164  in packer mandrel  112  and push against hub  152  of seal plate  11 . As seal plate  110  moves axially toward base cap  108 , rim  150  of seal plate  110  moves axially closer to shoulder  210  of base cap  108 , which causes expansion boot  114  to compressed axially between rim  150  and shoulder  210 . As expansion boot  114  is compressed axially, boot  114  also radially expands into engagement with an inner surface of pipeline  200 . In the radially expanded state illustrated in  FIG. 4B , expansion boot  114  is configured to substantially seal pipeline  200  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 pressure plate  134  of 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 spindle  106  to seal pipeline  200  and set brake assembly  116 . 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 spindle  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 spindle  106 . In another example, the actuator includes an electromagnetic piston that drives spindle  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  200 . 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  200  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 spindle  106  to cause expansion boot  114  to engage pipeline  200 , brake assembly  116  is also deployed to prevent or substantially inhibit movement of packer  100  within pipeline  200 . For example, as the pressure of the water strikes pressure plate of spindle  106 , central shaft  136  moves brake mandrel  166  axially toward seal plate  110 . Brake mandrel  166  drives tapered inner surface  182  of pads  168  along tapered outer surface  212  of packer mandrel  112 , which pushes brake pads  168  radially outward into engagement with the inner surface of pipeline  200  to prevent or inhibit packer  100  from moving within the pipeline. 
     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  200 . The offset distance between packer  100  and the inner surface of pipeline  200  may differ at different points along the axial length of packer  100 . For example, offset  214  between expansion boot  114  and the inner surface of the pipeline  200  is different than offset  216  between brake pads  168  and the inner surface of pipeline  200 . The outer periphery of end cap  106 , end cap  108 , seal plate  110 , expansion boot  114 , and brake assembly  116  may be configured to fit closely with the inner surface of pipeline  200  even when packer  100  is in an unengaged state. In one example, packer  100  is designed such that offset  214  is less than or equal to ⅛ inch, while offset  216  is greater than ⅛ inch. However, in other examples, offset  214  and offset  216  can be larger or smaller depending on the clearance between packer  100  and pipeline  200  necessary to allow packer  100  to be deployed through pipeline  200  and the amount of radial expansion of expansion boot  114  and brake pads  168  that is provided when spindle  106  moves axially toward base cap  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 less than or approximately equal to ⅛ inch will separate the sealing element of the packer and the pipeline inner surface and a radial clearance of less than or approximately equal to 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  214  between expansion boot  114  and the inner surface of the pipeline  200  is as small as possible while still allowing packer  100  to be deployed downpipe within pipeline  200 . In one example, the outer periphery of expansion boot  114  is configured to abut or nearly abut the inner surface of pipeline  200  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  200  and water striking pressure plate  134  of spindle  106  to cause packer  100  to become engaged with the inner surface of pipeline  200 . During the delay in actuation of packer  100  some water may pass through packer  100 . Reducing offset  214  between expansion boot  114  and the inner surface of the pipeline  200  will reduce the amount of water that floods pipeline  200  before packer  100  is engaged and expansion boot  114  substantially seals the inner diameter of the pipeline. 
     As is illustrated in  FIG. 4A , end cap  104 , base cap  108 , and packer mandrel  112  are hollow and seal plate  110  and brake mandrel  166  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  200  has an inner diameter that is approximately equal to 40 inches. The large size of pipeline  200  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 end cap  104 , base cap  108 , packer mandrel  112 , seal plate  110 , brake mandrel  166 , 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  200  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  200  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 pressure is balanced on either side of a wall of one or more of end cap  104 , base cap  108 , and packer mandrel  112 . In one example, packer mandrel  112  and brake mandrel  166  are configured to be substantially pressure balanced. 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 end cap  104 , base cap  108 , packer mandrel  112 , brake mandrel  166 , 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, end cap  104 , spindle  106 , base cap  108 , seal plate  110 , packer mandrel  112 , brake pads  180 , and brake mandrel  166  can be fabricated from a variety of different types of steel or aluminum. Expansion boot  114  and/or brake pads  168  can be fabricated from a variety of elastomeric materials including rubber. In one example, expansion boot(s)  114  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, expansion boot  114  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  114  may need to be fabricated from elastomers that can withstand relatively low temperatures without causing boot  114  to become too hard, stiff and/or brittle such that the disks are incapable of sufficiently sealing the inner diameter of pipeline  200 . 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  may also include a helical coil spring  218  arranged between pressure plate  134  and end cap  104 . Spring  218  can be employed to provide a number of functions related to engaging packer  100 . Spring  218  can be configured to provide force to assist the engagement of packer  100 . For example, spring  218  can be compressed between pressure plate  134  and end cap  104  when packer  100  is in the unengaged state illustrated in  FIG. 4A . Pressure plate  134  may be held in position against the force of spring  218  by pins (not shown) received in holes  220  in end cap  104  and engaging slot  140  in pressure plate  134 . The pins can be configured such that the force of water invading pipeline  200  shears the pins and releases pressure plate  134 . The force generated by spring  218  can push against pressure plate  134  to augment the force of the water pushing pressure plate  134  axially toward base cap  108 . Additionally, once engaged as illustrated in  FIG. 4B , the axially expanded spring  218  can function resist packer  100  from becoming unengaged and thus lock or partially lock expansion boot  114  and brake assembly  116  in engagement with the inner surface of pipeline  200 . 
     Packer  100  also includes quick-disconnect device  222 . In the event packer  100  is deployed to arrest a failure in pipeline  200  it may become necessary to disconnect packer  100  from hoist line  113 . In such cases, disconnect device  222  can be employed to disconnect hoist line  113  from packer  100  after the device has been engaged within submerged pipeline  200  to arrest a wet buckle or other type of pipeline failure. Disconnect device  222  includes a collet, at least a portion of which is received within central hole  132  in end cap  104 . In the first position of spindle  106  illustrated in  FIG. 4A , shaft  136  of spindle  106  engages the collet to lock disconnect device  222  to end cap  104 . In the second position, shaft  136  disengages the collet to unlock disconnect device  222  from end cap  104 . Examples of quick-disconnect devices that can be employed in conjunction with wet buckle packers in accordance with this disclosure are described and disclosed in U.S. application Ser. No. ______ (Atty. Docket No. 1880.516US1), filed on Jul. ______, 2013, and entitled “METHODS AND APPARATUS FOR ARRESTING FAILURES IN SUBMERGED PIPELINES,” the entire contents of which is 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 spindle  106 , base cap  108 , seal plate  110 , packer mandrel  112 , brake assembly  116 , and expansion boot  114 . Spindle includes pressure plate  134  disposed adjacent a first end of packer  100  including end cap  104 . Base cap  108  generally defines the second end of packer  100 . Seal plate  110  is disposed between pressure plate  134  and base cap  108 . Packer mandrel  112  and brake assembly  114  are disposed between pressure and seal plates  134  and  110 , respectively. Packer mandrel  112  includes tapered outer surface  212  and brake assembly  116  includes tapered inner surface  182  abutting the tapered inner surface of the packer mandrel. Elastomeric expansion boot  114  is disposed between seal plate  110  and base cap  108 . 
     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 spindle  106  axially toward base cap  108  from a first position to a second position. 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  134  of spindle  106 , which drives spindle  106  including central shaft  136  axially toward base cap  108 . In the second position, central shaft  136  drives posts  172  of brake mandrel  166  against seal plate  110 . Seal plate  110  is moved axially toward shoulder  210  of base cap  108  to axially compress and radially expand expansion boot  114  into engagement with the inner surface of the pipeline. Additionally, in the second position, tapered inner surface  182  of brake assembly  116  is caused to move axially along tapered outer surface  212  of packer mandrel  112  to cause brake assembly  116  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 and as a result of 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 Jul. ______, 2013, U.S. application Ser. No. ______ (Atty. Docket No. 1880.523US1), filed on Jul. ______, 2013, and U.S. application Ser. No. ______ (Atty. Docket No. 1880.563US1), filed on Jul. ______, 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.