Buoys – rafts – and aquatic devices – Buoyancy providing attachment for pipe – log – or line
Reexamination Certificate
2002-06-07
2004-05-25
Basinger, Sherman (Department: 3617)
Buoys, rafts, and aquatic devices
Buoyancy providing attachment for pipe, log, or line
C138S106000, C405S155000
Reexamination Certificate
active
06739926
ABSTRACT:
This patent application claims priority from U.K. Patent Application No. 0113971.6 filed Jun. 8, 2001, U.K Patent Application No. 0114805.5 filed Jun. 18, 2001 and U.K. Patent Application No. 0114912.9 filed Jun. 19, 2001.
This invention relates to a packing apparatus that is typically adapted for packing and/or supporting articles, such as pipes or pipe-work or equipment or machinery. The invention especially concerns damping of conductor tubes of offshore installations, such as fixed platforms, jack-up rigs and floating installations.
Many industrial structures and plant require a large network of pipes to convey fluids around the structure. In oil and gas plant, the large network of pipes requires a great deal of maintenance to control damage due to corrosion, erosion and fatigue. One particular problem associated with oil and gas plant is structural fatigue of pipes due to vibration. The vibration is generally unavoidable and typically results from the high-speed flow of fluid through the pipes, and on oil and gas platforms, it is general practice to support all pipes and pipe-work using structural supports. However, designing, making and installing these pipe supports is quite labour intensive, because the support brackets are generally fabricated in preset sizes, which may not precisely fit between a pipe and the nearest supporting structure. Therefore, in order to ensure a good fit between the pipe and the support bracket, shims are inserted on site between the pipe and the support bracket, so as to ensure that any space for vibration is minimised. Shims are also formed to pre-set sizes.
Drill conductor tubes in, for example, fixed offshore platforms run from the seabed up to the wellhead area passing through a series of guide tubes built into a steel jacket framework. The purpose of the conductor tube is to protect the high-pressure wellhead casing, which runs within it from environmental effects. The wellhead casing is guided within the conductor tube and hence the assembly moves laterally as a unit. The wellhead tree is attached to the top of the wellhead casing and is used for the connection of topside flowline pipework. The conductor and casing assembly acts as a tall slender structural element fixed at its base and carrying a large mass (the wellhead tree) at its top and having intermediate lateral guides in between.
The effects of wave and wind action are able to displace easily the conductor, which must then be restrained by the intermediate guides.
The conductors are installed after the jacket and topside structure by lowering the conductors through the jacket guides then grouting them into the seabed. The annular gap between a conductor and its guide tube must be sufficiently large to allow the conductor joint connectors to pass through and allow for misalignment of the guide tubes during fabrication of the jacket. The larger the gap the easier the conductors will be to install. However, a large gap will allow a conductor tube more freedom to move and hence cause large wellhead and flowline pipework movements. In addition, large impact forces will occur when the conductor tube contacts its guide tube.
Once the conductors are installed they can either have shims installed at the guides or they can be left free to move within the guides. In either situation problems can arise. If no shims are installed the conductors are free to move within the constraints of the guide tube. This should not affect the conductors or the guide tubes but the wellhead tree will experience larger than desirable movement and shock loading due to the conductor coming to an abrupt stop within its guide tube. This can cause large flowline pipework movement and vibrations, which can cause problems in the flowline pipework and attachments, in particular cumulative fatigue damage.
When shims are installed they tend to comprise steel strips forced down the annular gap between the conductor tube and its guide tube often completely eliminating any movement of the conductor tube. The practice of rigidly fixing the conductor tubes within the guide tubes is not recommended. Wave induced deflection of the conductor tube can induce large end moments if the conductor tube is rigidly fixed at its guide tube locations. The jacket guide tubes and framing members are generally not designed to resist these end moments. Local over stressing and fatigue problems can occur in the jacket structure if the conductors are rigidly fixed to the guide tubes.
An object of this invention is to provide a method and apparatus for packing or supporting articles, such as pipes, pipework, equipment or machinery.
According to the present invention there is provided a packing device comprising a container for containing a settable substance within the container.
Typically the container is flexible and/or deformable.
The container is typically placed between two items for packing purposes, typically so as to pack one item within the other and to limit the extent of movement of the one item within the other.
The settable substance is typically poured, injected or otherwise delivered into the container once the container is in place, and normally while the settable substance is in a liquid phase. After the container has been put in place and the settable substance has been delivered, optionally via a valve in the container, the viscosity of the settable substance then changes, so that the settable substance adopts a generally solid or at least a less fluid phase.
The viscosity of the settable substance delivered into the container can be varied, and although the viscosity of the settable substance is typically higher than the viscosity of the substance when initially delivered into the container, it is not necessary for the initial substance delivered to the container to be of low viscosity. For example, the initial settable substance delivered to the container could be a gel or a sol. Equally, while the viscosity of the substance once set is typically higher than when it is initially delivered into the container, the viscosity of the final set substance might also vary between applications, and in some embodiments could be a gel or a sol, while in other embodiments the final set substance could be a hard plastics material.
The compliance of the set substance can even be varied within the container, so that when the substance has set, the container has different zones of hardness. This is particularly useful where some pliability of the device is desirable in the immediate vicinity of the item to be packed so as to prevent some slight movement but so as to prevent excessive vibration or other movement beyond certain parameters. In such embodiments, the compliance of the substance disposed immediately against the item to be packed can be less than the compliance of the settable substance in other parts of the container, for example around the outside of the container, spaced apart from the item to be packed. This can be accomplished by different zones within the container containing different compositions of settable material, or by a gradient of compliance of the settable substance within the container.
The invention also provides a method of packing an item, the method comprising inserting a packing device between the item and an adjacent structural support, the packing device comprising a container, inserting a settable substance into the container and allowing or promoting a change of viscosity of the settable substance.
The invention also provides a method of supporting a pipe, the method comprising inserting an inflatable bladder between the pipe and an adjacent structural support so as to take free space between the pipe and the adjacent structural support.
The invention also provides a pipe support comprising an inflatable bladder.
Typically, the bladder is inflated with a fluid that is settable, i.e. a fluid that can adopt different phases.
Typically the settable substance is delivered into the container via a valve in the container, and sets hard over a period of time or when induced to set by a catalyst or the like
Cranston Peter Findlay
Crawford Brian James
Riach Michael Gordon
Amec Services, Ltd.
Basinger Sherman
Reed Smith LLP
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