Line Subcomponents

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Line Subcomponents

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A Line component may be comprised of any combination of the following line subcomponents. Note that the Material component is not exactly a direct line subcomponent, but nonetheless it is indirectly linked to a Line component through being used on other subcomponents.

'Material' is used to define the physical properties associated with a particular material. It may be regarded as a basic building block for all models, and is typically referenced several times in a particular project by higher-level components. For example, a Material component might be created to model steel, and this could be used subsequently in the specification of Pipe Section and Cable components. Both linear and non-linear material specifications are available, with several format options provided for the latter case.

'Pipe Section' allows the specification of cross section properties for a pipe in terms of geometry, weights, stiffness, hydrodynamic coefficients, coatings, etc. There are two methods of specification, Standard and Direct. The Standard specification references a Material component to automatically calculate weights and stiffness, whereas the Direct specification requires the definition of all properties manually. Options are also provided to specify coatings on the pipeline (representing for example insulation material or concrete), and to define the presence of discrete or continuous buoyancy material and/or strakes.

'Cable' allows the specification of cross sectional properties for a cable in terms of geometry, weights, stiffness, hydrodynamic coefficients, etc. It is similar to the Pipe Section component, but less complex. There are two methods of specification, Standard and Direct. The Standard specification references a Material component and assumes a solid cross section to automatically calculate weights and stiffness, whereas the Direct specification requires the definition of properties manually and assumes a stranded cross section in its calculation of stiffness.

'Flex Joint' is used to model flexible or articulated joints along a pipeline or stinger. They are characterised by length, weight and rotational stiffness values. The rotational stiffness can be either linear or non-linear (moment-angle curve).

'Structure' is a dedicated component for modelling in-line structures such as PLETs, PLEMs, ITAs, various sled assemblies, etc. It allows for the specification of geometric, stiffness and hydrodynamic properties for both the structure body and any rotating arm (labelled Yoke in the UI) that is attached to the body. The structure body and its centre of gravity can be offset away from the centreline of the pipeline. The same also applies to the rotating arm.

'Tapered Stress Joint' (TSJ) is used to model conical shaped joints along a pipeline. They are characterised by input values for length, weight and material type. The tapered shape is specified using diameters at the start and end of the joint and the intermediary diameters vary linearly from the start to end of the TSJ. It is also possible to define separate sections along the joint where the tapering can be changed.  

'Ancillary' is general purpose and can be used to model a variety of arbitrary line objects such as pull-heads, flanges, collars, etc. There are two specification options available for Ancillary components, namely Simple and Complex. The Simple option is just a point weight model with no length or structural properties. The Complex option enables specification by the physical dimensions, stiffnesses and hydrodynamic coefficients.

'Connection' is used to model arbitrary connections between a primary line and a secondary cable/pipe section/line. Three separate connection modelling options are available, namely, Free, Hinged and Clamped. The first option models a pinned constraint without providing any rotational restraint. A hinged connection has an associated rotational stiffness, simulating a pinned connection with some resistance to rotational motion. A clamped connection models a built-in connection with full moment transfer between the connected lines.

'Spring' is used to model the presence of piles or anchors. It is typically coupled with a fixed constraint in the model, in order to simulate a seabed restraint incorporating some degree of flexibility.