Patent Abstract:
An apparatus for protecting exposed pipeline joints on weight coated pipelines used in offshore applications includes a pliable cover sleeve which overlaps a pair of weight coat sections that surround the pipeline on each side of the pipe joint. The cover sleeve circumferentially envelops the pipe joint, forming an annular space enclosed between the pipe and the cover sleeve and bordered by the pair of weight coat sections. The cover sleeve includes a number of protruding ridges forming a number of chambers between the ridges in flow communication with the annular space. A joint-filling material of polyurethane foam formed by polyurethane chemicals fills the annular space and the chambers between the ridges of the cover sleeve. As the joint filling material hardens it interlocks with the ridges of the cover sleeve, securing the joint filling material between the cover sleeve and the pipe joint.

Full Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    The present application is a divisional application of co-pending, commonly owned U.S. patent application Ser. No. 10/943,578 filed Sep. 17, 2004. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The present invention relates generally to the protection of exposed pipeline joints of pipelines used in offshore operations, and relates more particularly to a pliable protective cover sleeve securing therein a protective substance in order to protect a pipe joint. 
       BACKGROUND 
       [0003]    It is conventional in the offshore pipeline industry to use weight coated pipe for pipelines which are used on ocean floors or other underwater surfaces. The weight coats traditionally have been made of dense materials such as concrete, and are typically several inches thick around the circumference of the pipe. The weight coats protect the pipeline and provide sufficient weight to maintain the pipeline submerged in a non-buoyant condition. 
         [0004]    In most cases, the weight coats are applied to the full length of the pipe except for a short distance where there is a bare pipe end portion, approximately one foot from the end of each pipe section. The end portion of the pipe remains without the weight coat to facilitate welding together individual sections of the weight coated pipe in order to make up the pipeline. In this manner, sections of pipe are placed on a barge and welded sequentially onto preceding sections forming a pipeline extending from the barge. The newly formed pipeline is placed on rollers, and as the barge moves forward, the pipeline is carried over the rollers, then lowered, and then laid on the bed of the body of water. 
         [0005]    The portions of pipe not having a weight coat had a corrosion coating applied to the surface of the pipe to prevent the pipe from corroding due to exposure to the elements. Generally, the corrosion coatings used were a heat shrinking tape or a fusion bonded epoxy. After the sections of pipe were welded together, various techniques were used to protect the corrosion coating on the exposed portions of pipe around each joint. 
         [0006]    One prior known procedure was to wrap sheet metal over the weight coating adjacent the exposed portion of the pipe and band the sheet metal in place with metal bands. Generally, a zinc coated sheet metal was used. The space between the pipe and sheet metal was then filled with a molten material which would solidify as it cooled. However, in most cases, the pipeline had to be in a condition for handling immediately after the sleeves were filled so that the laying of the pipeline could proceed without delay. The molten filling did not set or harden to a sufficiently strong material within the required time to allow further processing of the pipe and the molten material would leach out into the water if the pipeline was lowered before the molten material was adequately cured. 
         [0007]    Other known procedures have typically replaced the molten material with other types of materials. For example, one alternative material utilized to cover the exposed portion of pipe was granular or particulate matter such as gravel or iron ore which did not pack solidly or uniformly. Then elastomeric polyurethanes were injected into the mold to fill the interstices between the granular filler materials. After the polymer material had reacted, the mold would be removed from the surface of the infill. 
         [0008]    Another known procedure involves wrapping the exposed portions of pipe with a thermoplastic sheet. The sheet overlapped the ends of the weight coat adjacent the exposed joint and then was secured in place by screws, rivets, or straps. To increase the rigidity and impact resistance, this joint protection system required the installation of reinforcing members such as plastic bars or tubes to the interior of the sheet. The reinforcement bars or tubes either had to be precut and stored on the barge or else cut to the required fitting form as part of the installation process on the barge. Yet another known procedure entailed filling the lower portion of the annular space between the pipe and the plastic sheet with a material such as pre-formed foam half shells. 
         [0009]    A more recently used technique involved encasing the pipe joint by circumferentially wrapping a pliable sheet of cover material around the exposed portion of the joint connection. The longitudinal end portions of the pliable cover overlapped the adjacent edges of the weight coating, such that an annular pocket was formed about the exposed joint section. Polyurethane forming chemicals were then injected into the empty annular space where they reacted to form high-density, open cell foam which filled the annular space. The open cell polyurethane foam was intended to absorb moisture and ultimately increase the ballast of the pipeline. 
         [0010]    In many cases, vibrations during offshore operations at times could cause the foam to vibrate, and move around, tending to separate the foam from the pipe, because there was no locking mechanism to hold the polyurethane foam securely in its place. Of further concern, the outer diameter portions of the foam were more susceptible to movement, agitation, or damage than the inner diameter portions of the foam, because the outer diameter portions might have a lower density than the inner diameter portions of the foam. 
       SUMMARY OF THE INVENTION 
       [0011]    Briefly, the present invention provides a new and improved apparatus and method for protecting exposed pipe joints on weight coated pipelines used in offshore applications. A pliable synthetic resin cover sleeve overlaps a pair of weight coated sections that surround the pipeline on each side of the pipe joint. The cover sleeve circumferentially envelops the pipe joint, forming an annular space between the pipe and the cover sleeve and longitudinally between the pair of weight coated sections. The cover sleeve includes a number of ridges that extend inwardly from the sheet and form a number of chambers between the ridges. The chambers are in communication with the annular space. 
         [0012]    A filler composition is injected into the annular space, and the filler composition undergoes a hardening reaction to form a high density, open cell polyurethane foam. The annular space and the chambers receive the filler composition as it is reacting and the resultant high density, open cell polyurethane interlocks with the ridges in the cover sleeve while hardening. The expansion of the reacting, hardening foam into the chambers produces a locking effect with the structure of the ridges and the resultant polyurethane foam mechanically locks onto the ridges. 
         [0013]    The present invention forms a composite system to protect the joint connection with the foam providing continuous compressive reinforcements and impact resistance and the cover sleeve provides puncture resistance and protection from water jetting/post trenching operations plus abrasion resistance. The present invention further provides a better bond between the foam and the cover sleeve, which provides for greater overall stability and reliability. 
         [0014]    To better understand the characteristics of the invention, the description herein is attached, as an integral part of the same, with drawings to illustrate, but not limited to that, described as follows. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0015]    A better understanding of the present invention can be obtained when the detailed description set forth below is reviewed in conjunction with the accompanying drawings, in which: 
           [0016]      FIG. 1  depicts a side elevation view of a pipeline, showing two sections of weight coated pipe welded together at a pipe joint; 
           [0017]      FIG. 2  is an isometric view of a pliable cover sleeve according to the present invention shaped in cylindrical form and used to encase the exposed joint section; 
           [0018]      FIG. 3  is a side elevation view of a pipeline, showing a pliable cover sleeve according to the present invention wrapped and sealed around the exposed joint section; 
           [0019]      FIG. 4  is a vertical cross sectional view of the pipeline and cover sleeve of  FIG. 3 . 
           [0020]      FIG. 5  depicts a vertical cross sectional view taken along the lines  5 - 5  of  FIG. 4 , showing a locking mechanism of the cover sleeve interlocked with the joint-filling material. 
           [0021]      FIG. 6  shows a plan view of an unwrapped cover sleeve like that of  FIG. 2  in accordance with the present invention. 
           [0022]      FIG. 7  is a vertical cross-sectional view, like that of  FIG. 5 , but along the lines  7 - 7  of  FIG. 4 . 
           [0023]      FIGS. 8 ,  9 , and  10  are vertical cross-sectional views of alternative embodiments of the cover sleeve according to the present invention interlocked with the joint-filling material. 
       
    
    
       [0024]    To better understand the invention, we shall carry out the detailed description of some of the modalities of the same, shown in the drawings with illustrative but not limited purposes, attached to the description herein. 
       DETAILED DESCRIPTION 
       [0025]    Although the following detailed description contains many specific details for purposes of illustration, anyone of ordinary skill in the art will appreciate that many variations and alterations to the following details are within the scope of the invention. Accordingly, the exemplary embodiment of the invention described below is set forth without any loss of generality to, and without imposing limitations thereon, the claimed invention. 
         [0026]      FIG. 1  shows a conventional, prior art weight coated pipeline  10  formed by welding together two pipe sections  12 ,  14 , each of which is covered by a weight coat  16 ,  18 , respectively. The weight coat  16 ,  18 , which is formed from concrete or another suitable material, completely covers the pipe sections  20 ,  22  circumferentially and longitudinally except for a portion of each pipe end  24 ,  26  of the pipe section  20 ,  22 . The pipe ends  24 ,  26  are left exposed to facilitate welding of the two pipe sections  12 ,  14  together as sections of a pipeline. However, these exposed pipe ends  24 ,  26  leave gaps of pipe not coated with weight coat  16 ,  18  in the pipeline  10 , which would be covered only by a corrosion coating  34 . The present invention is provided to protect the pipe joint of the pipe ends  24 ,  26  between the coated pipe sections  16 ,  18 . 
         [0027]    As such, the present invention provides for the utilization of a cover sleeve  40  that is used to enclose and provide structural protection for the exposed corrosion coating  34  on the pipe end  24 ,  26 . As shown in  FIG. 2 , the preferred embodiment uses a cover sleeve material  40  that is pliable, yet strong, and which can be formed into a cylindrical shape to fit around the pipeline  10 . The coated end portion  16  is not shown in  FIG. 2  and the coated end portion  18  is shown in phantom so that structure of the cover sleeve  40  may be more clearly seen. The cover sleeve material  40  is formed from a high-density synthetic resin, polypropylene, polyethylene, or other alternative thermoplastic material. The cover sleeve  40  should be at least approximately 0.2 mm thick and may be considerably thicker if stronger support and impact resistance is desired. Water depth, pipe size, pipe weight and other considerations may dictate the use of a cover sleeve  40  which is up to approximately 12 mm in thickness. The cover sleeve  40  may be a flexible flat sheet or may be preformed into a cylindrical shape. 
         [0028]    An example of a suitable cover sleeve  40  is a sheet material in the form of a twin wall profile extrusion made from polyethylene or polypropylene that is manufactured, for example, by Primex Plastics Corporation, Richmond, Ind., and which may be identified by the brand name Cor-X. Sheet materials of this type can be extruded in thickness ranges of 0.006 to 0.5 inches. The sheet material used for the cover sleeve  40  is modified in a manner described below in order to permit ease of access of a joint infill or filler substance into the structure of the cover sleeve  40  and also to permit mechanical interlocking of the protective sleeve and the joint infill material. It should also be understood, as will be described in greater detail below, that the structure of the cover sleeve  40  may take a number of shapes to achieve such mechanical interlocking. 
         [0029]    For example, the cover sleeve material  40  may take the form of a wall  41  and a wall  42  spaced from and interconnected to each other by a series of ribs or ridges  44  between two outer layers arranged to extend over the length of the sleeve material  40  in a direction corresponding to the longitudinal axis of the pipeline  10 . Spaces between the walls  41  and  42  and adjacent ribs or ridges  44  thus take one form of a number of longitudinally extending tubes or passages  45 . As will be set forth below, portions of the wall  42  are removed or opened along both the longitudinal and transverse extent of the sheet material  40 . As a result when sheet material is formed into a cylindrical cover sleeve  40 , the tubes, or passages  45  take the form of chambers which are in flow communication with an annular space  54  formed between the sleeve  40  and the pipe  24 ,  26 . 
         [0030]    The pliable cover sleeve  40  is wrapped into a cylindrical shape around the exposed pipe ends  24 ,  26  such that the outer diameter of the cylinder of cover sleeve  40  is slightly greater than the outside diameter of the weight coat  16 ,  18  on the pipeline  10 . More specifically, the inside diameter of the cylinder of cover sleeve  40  is substantially the same as the outside diameter of the weight coat  16 ,  18 . The cover sleeve  40  should be long enough to overlap the adjacent ends or edges  30 ,  32  of both sides of the weight coating  16 ,  18  by several inches to allow the weight coating  16 ,  18  to act as a structural support for the cover sleeve  40 . Once the cover sleeve  40  is fitted over the adjacent edges  30 ,  32  of the weight coat  16 ,  18 , the longitudinal side edges  41  and  43  of cover sleeve  40  are tightly pushed together such that the side edges  41 ,  43  overlap. The cover sleeve  40  may be tightened down and held in place on the ends of the weight coat  16 ,  18  with conventional removable cinch belts (not shown) or some other form of securing structure. The outside edge  43  is then sealed to the surface of the cover sleeve  40  and the cylindrical, externally sealed cover sleeve  50  is formed. 
         [0031]    The cover sleeve  40  can be sealed by plastic welding an edge onto the surface of the cover sleeve  40 , forming a longitudinally extending plastic weld  43  the entire length of the cover sleeve  40  as shown in  FIG. 3 . Alternative techniques for sealing such as heat fusion, riveting, gluing, taping, or banding can also be utilized to seal the cover sleeve  40 . 
         [0032]    Referring to  FIG. 3 , the cover sleeve  40  thus becomes the cover sleeve  50 , sealed by the outer wall  41  forming a protective barrier around the exposed portion of pipe  24 ,  26  and remaining a permanent part of the pipeline  10 . The annular space  54  is thus formed around the pipe  24 ,  26  by installing the sealed cover sleeve  50 . The annular space  54  so formed between the pipe  24 ,  26  and the sealed cover sleeve  50  extends longitudinally between the weight coat portions  16 ,  18 . 
         [0033]    A hole  48  is formed in the sealed cover sleeve  50 , through which reactive chemicals or compositions are injected into the annular space  54  to form a joint-filler substance or composition  62 . The composition  62  is comprised of polyurethane chemicals of the type disclosed, for example, in U.S. Pat. No. 5,900,195 as described below. The hole  48  may be drilled, cut, or otherwise completed in the cover sleeve  50  to thereafter allow the yet-to-be reacted chemical or substance  62  to be injected into the annular space  54 . The hole  48  may be precut into the cover sleeve  40  prior to installation on the weight coated pipeline  10  or may be cut after the sealed cover sleeve  50  is in place. The diameter of the hole  48  to be drilled is dependent upon the particular type of mixing head used to inject the reactive chemical or substance  62 . Industry standard or conventional injection heads are acceptable, but suitable alternatives would also suffice. 
         [0034]    As shown in  FIG. 4 , the annular space  54  is filled through hole  48  by a mixing head with reactive chemicals or compositions, preferably those causing a reaction of components, such as those disclosed in U.S. Pat. No. 5,900,195. The composition  62  formed by such a reaction is, as a result, a high-density rapid-setting polypropylene or polyurethane foam system  62 . The foam  62  serves as a shock absorber and protects the corrosion coating on the pipe  24 ,  26 . Also, because the foam  62  is open celled, it can absorb water and increase the ballast effect for the pipeline  10 . Alternatively, other polymerizing or hard setting compounds such as marine mastics, quick setting concretes, polymers, or elastomeric compounds may be used to fill the annular space  54 . Any alternative filler substance  62  typically is quick hardening, such that the process of laying the pipeline  10  is not inhibited. 
         [0035]    The preferred polyurethane or polypropylene system utilized to form the protective high-density foam  62  in this process is a combination of an isocyanate and a polyol system. When reacted, this combination system rapidly cures and forms high-density open celled polyurethane or polypropylene foam  62 , which resists degradation in seawater. The isocyanate is a polymeric form of diphenylmethane diisocyanate, as manufactured, for example, by Bayer Corp. The preferred polyol system is a mixture of multifunctional polyether and/or polyester polyols, catalysts for controlling the reaction rate, surfactants for enhancing cell formation, and water for a blowing agent. The blended polyol system is manufactured, for example, by Dow Chemical Co., Bayer Corp., and other companies. 
         [0036]    The preferred system produces foam  62  with a density of about 8 to 10 pounds per cubic foot and has about eighty percent or greater open cells. The compressive strength of the preferred foam  62  is approximately 200 psi or greater at  10  percent deflection and 2000 psi or greater at  90  percent deflection. Reaction of the preferred system components can be characterized by a 18 to 28 second cream time, the time between discharge from the mixing head and the beginning of the foam rise, a 50 to 60 second rise time, the time between discharge from the mixing head and the complete foam rise, and a 240 to 250 second cure time, the time required to develop the polymer strength and dimensional stability. 
         [0037]    The cover sleeve  50  acts as a mold and receives the foam  62  in the annular space  54  and chambers  45 , and further interlocks and forms a mechanical bond with the foam  62  as it is cured. As shown in  FIG. 4 , preferably this foam  62  substantially fills the annular space  54  and chambers  45  without leaving significant void areas. Preferably, no additional filler materials are needed to be used in conjunction with the foam  62 . The foam  62  should substantially fill the annular space  54  and protrude to some extent upward through the hole  48  on the sealed cover sleeve  50 . 
         [0038]    Referring to  FIG. 4 , the sealed cover sleeve  50  together with the foam  62  provide a protective system which protects the exposed pipe  24 ,  26  and the corrosion coating  34  during handling and laying of the pipeline  10  and continues to provide protection from damage due to drag lines or trawler boards attached to fishing trawler nets. Further, the sealed cover sleeve  50  is not subject to the corrosion problems of prior systems and therefore does not create an underwater hazard or a danger to fishing nets. Additionally, the protective system provided by the present invention acts to deflect the high pressure water jets used to bury pipelines in shallow waters which have resulted in damage to the corrosion coating on pipe joints protected by prior systems. 
         [0039]      FIG. 5  depicts an axial cross section along the lines  5 - 5  in accordance with a preferred embodiment of the invention, showing the cover sleeve  50  filled and interlocked with the expanded, cured protective foam substance  62 . The wall  41  of cover sleeve  50  now serves as an outer wall of the cylindrical cover sleeve  50  and thus exhibits a smooth exterior. The ribs or ridges  44  of the cover sleeve  50  thus extend radially inwardly from an inner surface  41   a  of wall  41  in the assembled cylindrical cover sleeve  50  with the chambers  45  between them for receiving the protective foam substance as indicated at  72 . The size of the chambers  45  or and thus relative presence, or chambers-per-linear-foot extending in a circumferential manner around the interior of sleeve  50  may be varied according to needs of a particular pipeline. For example, the relative number may range from about fifty chambers per twelve inches to eighty or more chambers per twelve inches for walls  41  and  42  of cover sleeve  50  which may range in thickness from about 2 mm through about 6 mm. Further, cover sleeves  50  with wall thickness of from seven mm through twelve mm typically contain about thirty chambers per twelve inches. 
         [0040]    As shown in  FIG. 5 , the structure of cover sleeve  50  has the walls  41  and  42  connected by ridges  44  that hold the inner and outer walls together. The sleeve material is then modified such that a series of longitudinal cuts or slices  46  are formed extending through the inner wall  42  in a direction corresponding to the axis of the pipeline  10 . 
         [0041]    In addition, circumferential bands of the inner wall  42  are removed at longitudinally spaced positions as indicated at  74 . The longitudinally spaced positions can be relatively closer or further apart and the width of the circumferential band removed from inner wall is usually from ⅛ inch to about two inches along the interior of the cover sleeve for ease of entry of the reacting chemicals of the foam  72  into the chambers  45 . The inner wall  42  may be modified such that longitudinally extending portions or are removed between certain of the ridges  44 . The inner wall  42  thus may have a series of channels, as shown in  FIG. 2  at  75 . 
         [0042]    The cover sleeve  50  is thus a permanent outer cladding with from about ten to twenty circumferentially spaced ridges per square inch of the annular extent of the cover sleeve  50 , forming chambers  45  in flow communication with the annular space  54  being filled with the chemicals reacting to form the polyurethane foam  62 .  FIGS. 5 ,  7 ,  8 ,  9 , and  10  depict several possible embodiments forms suitable for the ridges according to the present invention. Generally the ridges have some portion extending in a direction transverse to a radial direction inwardly from the wall  41  toward the longitudinal axis of the pipeline  10  and cylindrical sleeve  50 . Thus, the ridges may take various forms, generally in the form of two portions, one of which is transverse the other in their final extent or location in the cured foam filing portions  62  and  72 ; or extending in a curved or arcuate direction away from the cylindrical inner wall; or in some combination of these or similar forms. It is desirable that some parts or portions of the structure of the ridges in their final location in the cured foam extend in a direction transverse that of a radius of the cylindrical sleeve  50 . In this manner, cured foam is located on each side of some portion of the ridges, thus interlocking with the inner structure of the ridges, sleeve rather than relying on physical bonding between cylindrical surfaces of the foam and the sleeve, as in previous infill coatings. 
         [0043]    The ridges  44  may be generally inverted T-shaped, as shown in  FIG. 5 , formed as a result of the slices  46  mentioned above with a first portion  44   a  of the ridges  44  extending inwardly from the inner surface  41   a  of the outer wall  41 . In the embodiment of  FIG. 5 , second portions  42   a  and  42   b  of the inner wall  42  on each side of the slices  46  extend transversely and generally substantially perpendicularly to the ridges  44 . The portions  42   a  and  42   b  thus extend perpendicularly across the ridges  44  as shown in  FIG. 5 . As can also be seen, the ridges  44  formed in this manner have an inverted T-shape in their extent inwardly into and interlocking engagement with the cured foam  62  and  72 . 
         [0044]    It should also be understood that the wall portions of the ridges to interlock with the foam may take a variety of other configurations. As examples, the cover sleeve  50  may have ridges  47  ( FIG. 8 ) or  48  ( FIG. 9 ) extending inwardly therefrom in the shape or design of a loop or a curved web extending in arcuate form from the cover sheet  50 . The webbed ridges  47  and  48  each have a space for the components reacting and forming the foam  62  to penetrate the chambers  72  and interlock with the ridges  47  and  48 . The arcuate segments  48  ( FIG. 9 ) are circumferentially disposed along the inner wall surface  41   a  of the cover sheet  50 , with alternate sets of the arcuate segments  48  formed with inner end portions spaced from each other to form a space  48   b  for entry of foam into the chambers  54 . In the embodiment of  FIG. 8 , the ridges  47  extend inwardly from the cover sleeve  50  in a somewhat comparable manner as do corrugation layers formed in cardboard materials. In the embodiment of  FIG. 10 , ridges  49  extend inwardly from the cover sleeve  50  in a generally hook-shaped manner. In each of the embodiments of the present invention, the chemicals reacting and causing the form  62  to be formed are able to enter the chambers  72  through the spaces shown between adjacent ridges or adjacent ones of the various ridges extending inwardly from the cover sleeve  50 . 
         [0045]    Turning now in greater detail to the embodiment shown in  FIG. 8 , the ridges may be formed as a series of arcuate segments extending inwardly from the cover sheet. The arcuate segments may take the form of undulating or wave-shape in vertical cross-section circumferentially disposed along the inner surface  41   a  of the wall  41  of cover sheet  40 , as shown at  47  in  FIG. 8 , with a central portion  47   a  mounted with or formed as an integral portion of the outer wall  41  and having two curved or arcuate segments  47   b  and  47   c  extending inwardly to be received in and interlock with the chemicals as they react to cause formation of the cured foam  62 . The arcuate segments  47   b  and  47   c  may result from forming longitudinal cuts or slices, leaving spaces  47   d  in a wave-shaped sheet of material  47 . Alternatively, the ridges may be in the form of a number of separate arcuate segments  47  mounted at spaced locations as shown at  47   d  from each other. 
         [0046]    Further, as has been discussed, the ridges may take the form of a series of arcuate segments, such as curved wall members  48  ( FIG. 9 ). As shown in detail in  FIG. 9 , the curved wall members  48  are formed extending in arcuate form circumferentially disposed and extending inwardly from inner surface  41   a  of the cover sheet with alternate sets of the curved wall members  48  having end portions  48   a  spaced from each other as shown at  48   b  to form chambers  45  in the flow communication with the annular space  54  to receive the foam  62  and  72 . 
         [0047]    Further, in another embodiment shown in  FIG. 10  ridges according for protective covers for joint infill according to the present invention may take the form of inverted-L or hook shape as shown at  49  in  FIG. 10 , with a first portion  49   a  extending inwardly from the inner surface  41   a  of the outer wall  41 . A second portion  49   b  of the ridge  49  extends transversely or perpendicularly to the first portion  49   a , with an optional third portion  49   c  extend generally radially inwardly to the wall  41 , leaving a space  71  providing flow communication for the foam  72 . 
         [0048]    It should also be understood that in the embodiments of  FIGS. 8-10 , circumferential bands as indicated at  74  and, where applicable, channels  75 , are typically present to provide flow communication so that the foam  62  as it is forming and cures penetrates and fills the chambers  45  as shown at  72 . The resultant foam in chambers  45  engages, interlocks, and substantially bonds with the ridges  70  in the interior of the cover sleeve  50 . As the foam  62  reacts to fill the annular space  54 , it also expands and substantially penetrates the chambers  45  formed by the ridges  44 . The present invention provides thus for a better mechanical bond at the interface between the polyurethane or polypropylene foam  62  and the cover sleeve  50 . 
         [0049]    It should be understood that the ridges  44  extending inwardly from the cover sleeve  50  may take a number of forms according to the present invention. For example, the invention cover sleeve  50  need not have both longitudinal cuts  46  and circumferential bands  74  for flow communication from the annular recess  54  into the chambers  45 . The cover sleeve  50  may thus be provided with only longitudinal cuts  46  or circumferential bands in inner wall  42  for fluid communication. 
         [0050]    It should be understood that the Figures of the present invention are generally not drawn according to scale with respect to the relative sizes of various structural elements shown. Rather, the relative size of some of the structural elements are enlarged in comparison to other structure in order to more clearly illustrate the features of such structural elements. For example, in FIGS.  5  and  7 - 10 , the ridges are enlarged in comparison to cover sleeve  50  in order to more clearly illustrate the structure of the ridges and their interlocking with the filler foam substance  62 . 
         [0051]    From the foregoing, it can be seen that the present invention provides an apparatus and method for protecting the corrosion coating  34  on exposed pipeline joints such as  12 ,  14  on weight coated pipelines  10  used in offshore applications. The cover sleeve  50  and the foam  62  work together to protect the joint connection. The aforementioned methodology allows quick installation on a lay barge where pipeline sections  24 ,  26  are being welded together for offshore installation. The present invention further provides a locking mechanism to secure the foam  62  inside the cover sleeve  50 , thus preventing the foam  62  from subsidence away from the cover sleeve  50 , or movement or agitation relative to the pipe in a circular or circumferential manner around the pipe, which otherwise may occur from vibrations occurring during offshore operations. 
         [0052]    Moreover, because the outer diameter portions of the foam  62  may have a lower density than the inner diameter portions of the foam  62 , prior embodiments in the art indicate that the outer diameter portions of the foam  62  are more susceptible to movement or agitation relative to the pipe than the inner diameter portions of the foam  62 . For this reason, the positioning of the locking mechanism on the outer side of the foam  62 , rather than on the inner side of the foam  62 , should be regarded with considerable importance. 
         [0053]    The invention can be used for pipe joints that are part of a pipeline located on the floor of a body of water. The invention can be used in many applications, including use as a deep water insulation joint infill, and as a deep sea abrasion sleeve. In this manner, a better, more secure, and more stabilizing bond is formed between the foam  62  and the cover sleeve  50 , which provides greater overall stability and reliability during offshore operations. Thus, the present invention improves the performance of pipelines where pipe ends  24 ,  26  are welded together on pipelines coated with concrete weight coating  16 ,  18  and installed on the seabed in large bodies of water. 
         [0054]    The invention has been sufficiently described so that a person with average knowledge in the matter may reproduce and obtain the results mentioned in the invention herein Nonetheless, any skilled person in the field of technique, subject of the invention herein, may carry out modifications not described in the request herein, to apply these modifications to a determined structure, or in the manufacturing process of the same, requires the claimed matter in the following claims; such structures shall be covered within the scope of the invention. 
         [0055]    It should be noted and understood that there can be improvements and modifications made of the present invention described in detail above without departing from the spirit or scope of the invention as set forth in the accompanying claims.

Technology Classification (CPC): 5