Abstract: The use of fluid passages for structures in fluid environments such as offshore platform risers or spars to reduce and/or control vortex-induced vibrations and drag is disclosed. The use of fluid passages to protect a moored marine vessel by reducing and/or controlling low frequency drift oscillations due to random waves, and low frequency wind induced resonant oscillations is also disclosed.

Abstract: A riser guide system is for use on a floating offshore platform, the platform having a topside and a substructure having a lower pontoon, and at least one riser extends from a subsea location to the topsides. A permanent guide is secured to the pontoon, a primary guide is located in the permanent guide, a secondary guide is located in the primary guide, and riser guides are located in the secondary guide and face the riser. In a method for installing the riser guide system, both the primary guide, the secondary guide and the riser guides are placed around the riser at the topsides, and lowered down to the pontoon.

Abstract: A riser guide is for use on a floating offshore platform, the platform comprises a topsides and a substructure having a lower pontoon, and at least one riser extends from a subsea location to the topsides. A number of riser guides are located in a guide housing which is secured to the platform. Each riser guide comprises a support arm rotatably mounted in the guide housing. A roller for laterally guiding the riser is rotatably mounted in an end of the support arm. A vertically movable wedge which is used for lifting the guide housing is connected to the support arm. During lifting of the guide housing the wedge lifts the support arm and the roller to an inactive position. When installing the riser guides, the guide housing and the riser guides are placed around the riser at the topsides, and lowered down in place by lifting gear connected to the wedges.

Abstract: A riser pipe construction for a drilling connection from a drilling vessel to a valve previously provided on a sea floor comprises a riser pipe through which drilling means can be passed by means of which an oil well can be drilled as well as pressure pipes extending along the riser pipe to operate the valve, and floating elements disposed around the riser pipe and the pressure pipes to limit the load on the drilling vessel. The riser pipe and the pressure pipes are built up from modules capable of being coupled together, the floating elements are formed by steel tubular chambers closed so as to be gastight, disposed around the relevant modules and firmly connected thereto. The invention also relates to a riser pipe module.

Abstract: A semisubmersible floating platform for use in marine environments. The platform comprises a truss telescopingly mounted to the platform and movable between upper and lower positions with respect to the platform. At least one riser buoyancy member is telescopingly mounted to the platform and movable between upper and lower positions with respect to the platform. For each riser buoyancy member, at least one guide is attached to the truss and adjacent the buoyancy member for guiding and laterally restraining the buoyancy member.

Abstract: A buoyancy system for deep-water risers of a deep water floating platforms includes an ecto-skeleton formed by a plurality of members to withstand lateral and bending loads, and a buoyant vessel disposed in an interior cavity of the ecto-skeleton to resist pressure loads. The member of the ecto-skeleton can include hollow tubular members having hollow interiors with a buoyant material disposed in the hollow interiors of the tubular members.

Abstract: Expandable and contractible buoyancy modules are assembled to the risers of a deepwater exploration spar or other offshore structure to provide an upwardly directed buoyancy force to offset at least a portion of the weight of the riser. The buoyancy modules have a fabricated pressure tight expandable and contractible envelope composed of rubber or rubber-like material which is mounted onto a tubular member having a central passage for receiving the riser to be supported. The tubular member projects beyond the respective upper and lower ends of the envelope and defines upper and lower riser joint connectors and buoyancy module travel stops which secure the buoyancy module to the riser and provide for force transmission from the buoyancy module to selected locations along the length of the riser or to the upper end of the riser.

Abstract: Systems are described for raising production fluid from a source (1) on the seabed comprising a riser (4) having a first, lower, end for connection or connected to the source; a top end support for supporting the riser at or in the vicinity of the sea surface; and an operating device (11) mounted inside the riser (4) for displacement within the riser so that the pump is accessible to an operator for replacement or repair. The operating device (11) may be displaced on a pipe (12) which extends within the riser (4) and to a lower end of which the device (11) is attached. The device (11) may be inter alia an electric pump, a hydraulic pump, a gas injector, a heater or a cleaning device.

Abstract: A composite riser for transporting fluids between a location on a seabed and an installation near or at the surface of the sea comprises an outer sheath of tubular form extending longitudinally in a lengthwise direction of the riser, a plurality of spacing members arranged within the outer sheath so as to define a plurality of longitudinally extending channels in the outer sheath from one end to an opposite end of the riser, and a plurality of fluid-carrying tubes disposed in the channels such that the tubes are freely movable in the lengthwise direction of the riser relative to the outer sheath, the tubes being constructed of fiber-reinforced plastic material. One or more tension members are disposed in the channel(s) and are freely movable relative to the outer sheath in the longitudinal direction.

Abstract: An offshore loading or production system for dynamically positioned ships, comprising a riser means (4) extending between a supply means and a coupling head (5) for connection to a connecting means (6) on the ship (1). The riser means (4) comprises a lower riser portion (7) extending along the seabed (8) and being arranged to take up a wavy shape above the seabed by means of at least one bottom-anchored first buoyancy element (9), and an upper riser portion (10) of which the lower end is connected to the lower riser portion (7) via a second buoyancy element (11), and of which the upper end is connected to the coupling head (5) via a swivel unit (12). The second buoyancy element (11) is connected to a supporting anchoring (17) extending along the seabed (8) in a direction away from the lower riser portion (7).

Abstract: A buoyancy system to buoy a riser of an offshore oil platform includes buoyancy compartments coupled around an elongated internal beam. The internal beam can withstand loads between the oil platform and the buoyancy system, while the buoyancy compartments provide buoyancy. The internal beam includes an elongated stem, a plurality of webs extending radially outwardly from the stem, and a plurality of transverse flanges attached to the outer edges of the webs.

Abstract: The present invention relates to a ball swivel connection/joint intended to be used at anchoring of in particular deep sea water boring rigs and other off-shore platforms but also other heavy units at sea, whereby it comprises a partly spherical wire connection receiving a wire receiving unit a substantially annular link connector as well as a holding element for a fixed or movable fixation of the link connector as well to an annular space arranged in the partly spherical connector, whereby the link connector and the wire receiving unit are rotatably arranged relative each other.

Abstract: A frame and system for adding buoyancy to a riser used in connection with floating platforms is provided which, in some example embodiments, includes a stem attached to multiple supports which include flanges arranged to take impact and abrasion loads off an internal buoyancy module. An air management system is also provided.

Abstract: There is provided a buoyancy system for a structure having at least one component being substantially stationary with respect to the bottom of a water covered area. The system comprises a set of buoyancy modules of engineered materials to apply an identified amount of buoyancy. The set of buoyancy modules is attached to the structure at a set of buoyancy load transfer locations. The set of buoyancy modules comprises layers of the engineered materials. The engineered materials comprise a substantially reinforced axial layer, a substantially reinforced hoop layer; and a leak prevention layer.

Abstract: A system for supplying cooling water to a process on board a floating vessel for the production of hydrocarbons, wherein the vessel (1) is anchored by means of a bottom-anchored turning unit (20) mounted in a receiving space (7) in the hull (34) of the vessel and allowing turning of the vessel (1) about the turning unit, and wherein the turning unit (20) supports a swivel unit (24) for the transfer of hydrocarbons from production risers (28) extending between the seabed and the turning unit (20), the system comprising a conduit means (30) depending from the vessel (1) to a depth for taking in cooled sea water, and a pump means (44) for pumping of the sea water from the conduit to a place of use for the process.

Abstract: A mid-water tethered buoyant support assembly for a riser system for use in water is described to bring fluids from seabed equipment to a production vessel at the surface. The tethered buoyant support assembly comprises at least two tethers (6) from seabed anchors, at least one beam assembly (2) extending between and connected to the tops of the tethers, buoyancy means (7) to maintain tension in the tethers, and hangers (10) for lower riser portions mounted at spaced positions along the beam assembly, each hanger (10) being positioned so that the line of action of the tension due to the weight of the suspended lower riser portion is close to or on a line extending between the connections of the beam to the tethers (6) to minimize or eliminate turning moment to the beam assembly (2) tending to cause rotation of the beam around its major axis as a result of the weight of the suspended lower riser portion. The assembly is particularly designed for use in deep water.

Abstract: A method and apparatus for connecting riser between a floating vessel and a subsea structure that reduces the size of the air tanks used and thereby allow closer positioning of the well slots and overall reduction in size of the floating vessel is disclosed. The apparatus includes an inverted hydraulically actuated connector positioned on the subsea structure and oriented to receive and sealingly attach to a complementary end connection member on the lower end of the riser string.

Abstract: Gas storage is provided for a subsea gas-lifted riser during offshore drilling and/or production operations. One or more gas storage chambers positioned along and about the subsea riser are connected to a gas conduit. Each chamber has at least one valve for controlling passage of gas out of the chamber and into the gas conduit. The valves serve to allow the gas from the storage chambers to be injected as lift gas as needed.

Abstract: An air-can riser tensioning device for use in the production of oil and gas at offshore locations includes at least one air-can used to place a vertical force on the riser. The air-can includes an open port that extends into the water toward the sea floor to a depth sufficient to prevent water from entering or air from leaving the air-can during its upward and downward vertical movements while in use. A manufacturing method includes fabricating the air-cans out of one material and fabricating the open port out of another material, and in particular making the open port from a material that is more corrosion resistant than the material the air-can is fabricated from. The manufacturing method further includes fabricating a passage in one soft tank for fluid communication with a second soft tank, and connecting the second soft tank with the passage.

Abstract: A vessel includes a riser and/or tendon tensioning construction. A connector, such as an arm or deck structure, is suspended from pivot arms on the vessel. The connector carries two or more risers and/or tendons extending from a subsea structure to above water level. The free end of the pivot arms is attached to a weight for exerting a tensioning force on the riser which is substantially decoupled from pitch, roll and heave motions of the vessel.

Abstract: A loading arrangement includes a riser that extends from a subsea structure to a coupling element for coupling the riser to a vessel. The coupling element includes a buoy body which is connected to a retention member via a flexible connection part. The retention member, such as a submerged buoy, is attached to anchor lines which at or near their end parts are provided with buoy. The connection part, which can be a cable or a frame structure has a relatively high tensile strength to anchor the vessel to the sea bed and to prevent drift of the vessel when tension is exerted on the connection part and the anchor line.

Abstract: An apparatus for offshore production of hydrocarbon fluids is disclosed. The apparatus comprises a base and a buoyant structure secured to said base and connected or adapted to be connected to a subsea well or wells. The key characteristics of the apparatus are that: (A) the apparatus includes storage facility means for fluid(s) received from the subsea well or wells and/or for processed fluid(s) produced by the apparatus; (B) the buoyant structure is tethered to the base by a plurality of flexible tethers; and (C) the buoyant structure comprises (i) a sub-surface housing containing facilities for processing fluids received from the subsea well or wells via said storage facility in said base; and (ii) a column extending upwardly from the housing to a level above the sea surface. The invention also relates to the buoyant structure per se.

Abstract: A floating platform system supports one or more decks (14) above the water surface for accommodating equipment to process oil, gas and water recovered from a subsea hydrocarbon formation. The platform is secured to the seabed by one or more tendoms (17). A central column (12) of the platform includes a moonpool (19) extending axially through the central column (12). The moonpool (19) is open at the lower and upper ends thereof. Riser lateral restraint members (32) are supported within the moonpool (19) for laterally restraining risers (16) disposed in the moonpool (19) and minimizing riser spacing and riser deflection.

Abstract: A tensioner for providing a conduit, e.g., drilling and production riser strings, from a floating vessel at the surface of the ocean to the blowout preventer stack, production tree, or other assembly which is connected to the wellhead at the sea floor. The tensioner compensates for vessel motion induced by wave action and heave and maintains a variable tension to the riser string alleviating the potential for compression and thus buckling or failure of the riser string. The tensioner of the present invention preferably includes at least one mandrel having at least one hang-off donut; at least one upper flexjoint swivel assembly, at least one radially ported manifold, and at least one tensioning cylinder co-linearly combined in a single unit. Methods for assembling risers are also disclosed.

Abstract: Discharge of fluid into or suction of fluid from the boundary region around such structures as offshore marine elements and moored marine vessels to reduce fluid current induced stress to marine elements and low frequency oscillations of moored vessels due to waves and wind striking the vessel is disclosed.

Abstract: A connection between a riser and a receptacle of a floating platform may be preloaded to reduce fatigue. The platform has a receptacle with upper and lower grooved profiles. A hanger is connected to the upper end of the riser. The hanger has a latch that engages the lower grooved profile in the receptacle to resist downward pull of the riser. A tieback connection inserts from above into the receptacle. The tieback connection has an outer member that lands on the hanger. The outer member has a latch that engages the upper grooved profile. The tieback connection also has an inner member with a set of internal threads. Threads on the inner member engage threads on the latch, rotating the inner member relative to the outer member exerts an outward force on the tieback connection latch. As the latch is pushed into the tieback grooved profile, a downward preload force is created, which passes to the hanger latch.

Abstract: A substantially rigid riser to offshore platform connector and a process of using the connector allows a riser to be preloaded and adjustably positioned relative to the offshore platform. The connector allows the riser tensile load to be limited by preloading and adjustably positioning the connector. In the preferred embodiment, hydraulic cylinders are used to preload the connector as well as to partially or fully support the riser during maintenance or repair procedures.

Abstract: A device in connection with a riser (1) for the transport of oil and/or gas, possibly including water, from a transport system, transport pipe (5) or similar structure on the sea bed to a platform or similar arrangement. To permit the use a riser (1) for the transport of oil and/or gas from a small field with low oil/gas production where a transport pipe (5) with a small diameter is used, a flexible pipe (4) with generally the same internal diameter as the transport pipe (5) is arranged inside the riser (1). At its upper and lower ends, the riser (1) is provided with a coupling (6, 7), which forms a seal between the transport pipe (5) and the flexible pipe (4) and also forms a seal at the ends of the riser so that the riser is closed.

Abstract: A bottom-to-surface link system includes a submarine pipe assembled to at least one float. At least one coaxial can surrounds the pipe. Junctions, which join the can to the pipe at the top and bottom orifices through which the pipe passes, include leakproof joints assembled around the pipe. Furthermore, the leakproof joints are flexible and resilient and are of the laminated abutment type.

Abstract: A riser connector is provided for connecting a riser to a wellhead assembly having a bore therethrough. The connector includes a housing having a first and a second end. The first end of the housing has an opening and is adapted for mounting to the wellhead assembly with the opening in communication with the bore of the wellhead assembly. The second end has a first opening connectable to the riser having a diameter at least the same as the inner diameter of the riser, and a second opening, having a diameter at least substantially the same as the diameter of the bore of the wellhead assembly. The housing further includes a first conduit connecting the opening in the first end of the housing to the first opening in the second end of the housing, and a second conduit connecting the opening in the first end of the housing to the second opening in the second end of the housing. In use, first well operations are conducted through the riser in the conventional manner.

Abstract: A vessel includes a riser and/or tendon tensioning construction. A connector, such as an arm or deck structure, is suspended from pivot arms on the vessel. The connector carries two or more risers and/or tendons extending from a subsea structure to above water level. The free end of the pivot arms is attached to a weight for exerting a tensioning force on the riser which is substantially decoupled from pitch, roll and heave motions of the vessel.

Abstract: A loading arrangement includes a riser that extends from a subsea structure to a coupling element for coupling the riser to a vessel. The coupling element includes a buoy body which is connected to a retention member via a flexible connection part. The retention member, such as a submerged buoy, is attached to anchor lines which at or near their end parts are provided with buoy. The connection part, which can be a cable or a frame structure has a relatively high tensile strength to anchor the vessel to the sea bed and to prevent drift of the vessel when tension is exerted on the connection part and the anchor line.

Abstract: The present invention relates to a method of dimensioning a riser assembly (1) intended for offshore drilling, connecting an underwater wellhead (2) to a floating support (7) comprising a main pipe (8), wherein the following stages are carried out:

Abstract: Keel joint assemblies are described that permit a degree of rotational movement of a riser within the keel of a floating vessel and greatly reduce the amount of stress and strain that is placed upon the riser, as well. Keel joint assemblies described provide a limiting joint between the riser and the keel opening that permits some angular rotation of the riser with respect to the floating vessel. Additionally, the limiting joint permits the riser to move upwardly and downwardly within the keel opening, but centralizes the riser with respect to the keel opening so that the riser cannot move horizontally with respect to the keel opening. In described embodiments, the limiting joint is provided by a single annular joint that allows that riser to move angularly with respect to the can. In some embodiments, the keel joint assembly incorporates a cylindrical stiffening can that radially surrounds a portion of the riser and is disposed within the keel opening.

Abstract: A riser connected by a trunnion mounted/pivoting riser support to a disconnectable body or to a riser table of a permanently connected turret. The trunnion includes a trunnion housing and trunnion pivot. The trunnion housing is arranged to allow a riser to pass through it and up to a vessel turret where the disconnectable body is connected to the turret. The trunnion pivot allows the trunnion housing and riser to pivot about a horizontal axis, allowing a disconnectable body to submerge to the sea floor.

Abstract: The present invention provides heave compensation through a riser tensioner for a marine riser (8) supported from a sea vessel (100) supporting a cylinder barrel (11) with a mainly vertically arranged cylinder axis (110). The cylinder is provided with a piston (12) with an outer diameter corresponding to the cylinder barrel (11) and arranged coaxially inside the cylinder barrel (11). The cylinder barrel (11) has a larger diameter than the riser (8). The cylinder barrel (11) has an upper end (5) communicating with the atmosphere through a vent channel (6c) from a volume (6a) above the piston (12), the vent channel (6c) and the volume (6a) arranged for being air-filled, excerting an atmospheric pressure downwards on the piston (12).

Abstract: A marine buoy for the offshore support of subsea production and drilling activities that has a closed-bottomed base section with a solid ballast and variable ballast chambers, a chamber in the base section for storing equipment and supplies, and an upper section with a smaller cross-sectional area than the base section having an elevator shaft leading from the top of the upper section to the chamber in the base section. The upper section supports a deck for housing process equipment for operations that the marine buoy is supporting.

Abstract: A buoyancy system for a deep water floating platform includes at least one composite buoyancy module coupled to the a riser having a length greater than 1000 feet and an associated weight. The composite buoyancy module is sized to have a volume to produce a buoyancy force at least as great as the weight of the riser. The composite buoyancy module may include a vessel with a composite vessel wall. The buoyancy module or vessel may have a non-circular cross-section defining an area which is greater than approximately 79 percent of an area defined by a square with sides tangent to the vessel wall to maximize buoyancy. A second buoyancy module may be directly coupled to the first buoyancy module to achieve a desired buoyancy.

Abstract: A method and apparatus for connecting riser between a floating vessel and a subsea structure that reduces the size of the air tanks used and thereby allow closer positioning of the well slots and overall reduction in size of the floating vessel is disclosed. The apparatus includes an inverted hydraulically actuated connector positioned on the subsea structure and oriented to receive and sealingly attach to a complementary end connection member on the lower end of the riser string.

Abstract: The present invention relates to a bottom-to-surface link system for an underwater pipe installed at great depth, the system comprising: firstly a vertical tower constituted by at least one float (5, 14) associated with an anchor system (6, 8, 16) and carrying at least one vertical riser (9, 15) suitable for going down to the sea bed (18); and secondly at least one link pipe (4, 3) extending from said float (5, 14) to a surface support (1). According to the invention, said link pipe is a riser whose wall is constituted by a rigid steel tube, and said float (5, 14) is installed at a depth situated below the last thermocline (29).

Abstract: A riser tensioning device for use on an offshore floating facility comprising a buoyancy element and a frame. The frame accepts external loads caused by movement of the floating facility and wave and/or current action that would otherwise act on the buoyancy element. The frame can be made positively or neutrally buoyant so that the weight of the frame does not counteract the buoyancy provided by the buoyancy element.

Abstract: A drilling unit comprises a floating drilling rig, a subsea wellhead, and a riser connecting the subsea drilling rig with the subsea wellhead. A floatation collar encircles the riser so as to reduce deck load on the floating drilling rig. The floatation collar comprises a hollow fabric body filled with gas. The floatation collar has a longitudinal axia and is formed from a sidewall body having a longitudinally extending slit extending through the sidewall body. The slit enables the floatation collar to be transversely mounted onto the marine riser.

Abstract: An extended-base tension leg substructure, an offshore platform supported on the substructure and a method for supporting an offshore platform on the substructure are disclosed, where the substructure includes a plurality of support columns disposed about a central axis of the substructure and interconnected by at least one pontoon. Each column comprises an above water and submerged portion. The substructure also includes a plurality of wings or arms radiating from the columns and/or the pontoons, each wing fixedly or removably securing at least one tendon extending from a wing to an anchor on the seabed. The substructure includes an open, wave transparent central zone for improved access to well-related equipment, conduits or the like and the wings minimize translational movement and rotational flex in the substructure reducing fatigue in the tendons and their connections.

Abstract: A buoyancy system for a deep water floating platform includes at least one composite buoyancy module coupled to a riser. The module includes an elongate vessel with a vessel wall, and upper and lower ends. The vessel is attached to the riser, vertically oriented, and submerged under a surface of water such that the upper end is disposed at a lower water pressure, and the lower end at a higher water pressure. The vessel wall has a thickness that varies from a thinner wall thickness at the lower end to a thicker wall thickness at the upper end. The vessel may be internally pressurized with air such that an internal air pressure of the vessel substantially equals the higher water pressure at the lower end of the vessel resulting in a lower pressure differential at the lower end with the thinner wall thickness and a higher pressure differential at the top end with the thicker wall thickness. The module is sized to have a volume to produce a buoyancy force at least as great as the weight of the riser.

Abstract: A buoyancy system for a deep water floating platform includes at least one buoyancy module coupled to the a riser. The module may be coupled to a ring structure of an end cap coupled to the riser, or two modules may be coupled to a ring structure to couple them together. The modules have an interior flange extending into the interior cavity and abutting the ring structure. Fasteners couple the interior flange of the module to the ring structure to form an interior attachment. A seal may be formed between the flange of the buoyancy module and the ring structure, and may include a seal member disposed in a groove. A test port extends to the groove to allow testing of the seal. The module may include a material and may have a thickness that together allow a wall of the buoyancy module to expand outwardly under an internal pressure and force the flange against the ring structure to enhance sealing between the flange and ring structure.

Abstract: An attachment extends between an outer sleeve and an inner riser pipe where the pipe penetrates the keel of a platform. In one version, the attachment is a conically-shaped with a small diameter ring that engages the riser pipe and a large diameter ring that engages the outer sleeve. This attachment has elements that are very flexible in bending but relatively stiff and strong in axial load. Other versions include flat rings where lateral load is taken directly into tension and compression in the beams, allowing for relatively high lateral load transfer. Both the conically-shaped attachment and the flat ring have a number of variations that provide low bending stiffness but high axial stiffness of the elements. Depending on whether resistance to axial loads, lateral loads, or resistance to combination of both loads is desired, the attachment and the flat ring may be used alone or in combination.

Abstract: An apparatus for releasably securing a tubular structure of a floating installation to an anchor fixedly secured to an underwater floor has a first connection element mounted at one end of the tubular structure and a second connection element configured at one end to couple with the first connection element. The second connection element includes a pair of guides secured thereto which extend horizontally therefrom. A hinge device connects the second connection element to the anchor such that the second connection element is pivotably connected to the anchor. A plurality of cables connect to both the tubular structure and the anchor, whereby the pair of guides cooperate with the cables such that when the cables are under tension, the cables urge the second connection element to pivot and align with the first connection element.

Abstract: An installation for producing oil from an off-shore deposit has a semi-submersible platform, at least one riser connecting the platform to the sea bed, and devices for tensioning the riser. The tensioning devices include, for each riser, at least one submerged float connected to a point on the main run of the riser for hauling it towards the surface, and a mechanism for hauling the riser. The mechanism is installed on the platform and applied to the top end of the riser.

Abstract: A riser for drilling with a subsea wellhead and a method for adjusting the boyancy of a pipe. The riser includes tubular elements (1) linked together by connecting devices (2). The elements include a floating device consisting of a box (6) in which a determined volume of gas can be pumped so as to modify the apparent weight of the element in the water. At least one tubular element comprises detectors (12) for measuring the differential pressure between the inside and the outside of the box, a value device (14) for filling the box with gas, a bleed valve device (15) for discharging the gas from the box, a control transmission and reception unit (13) for controlling the filling valve device and the discharge bleed valve device considering the differential pressure measurement.

Abstract: An apparatus for rapid venting of the compressed air and deballasting of a buoyant air tank in a positively buoyant riser system in the event of a premature drive off or a riser section parting is shown. The buoyancy tank or housing includes an annularly shaped flange positioned on its upper end and retained by explosive bolts. The inner circumference of the flange is sealed to the riser section supported by the buoyancy housing. A sensing means, activated by a parting of the riser, actuates the explosive bolts to release the annularly shaped flange and flood the buoyancy housing while restraining lines limit movement of the buoyancy housing with respect to the riser section.