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Marine Growth

General

The marine growth affects the pipes following parameters:

  • Mass in air:

$$ M_{air_MG} = M_{air} + \pi \frac{((OD + 2 * t_{MG})^2 - OD^2)}{4} * \rho_{MG} $$

  • Submerged weight:

$$ M_{water_MG} = M_{water} + \pi \frac{((OD + 2 * t_{MG})^2 - OD^2)}{4} * (\rho_{MG} - \rho_{water}) $$

  • Hydrodynamic diameter:

$$ OD_{h_MG} = OD_h + 2 t_{MG} $$

  • Buoyancy diameter: the buoyancy diameter considered when marine growth is applied is more difficult to determine. Indeed as the contact diameter is based on the buoyancy diameter the user shall defined if he accepts the contact either on the marine growth layer or only on the pipe. In general case the buoyancy diameter is defined as follows:

$$ OD_{B_MG} = OD_B + 2 *t_{MG} $$

  • Hydrodynamic coefficients: marine growth roughness and increased pipe diameter lead to modified hydrodynamic coefficients that can be specified by the user

  • Note that the marine growth profile modifies the apparent weight of a line even if the option "submerged weight" is selected in the properties of the line.

Marine Growth Profile Type Panel description

A new object "Marine Growth" can be created and is be accessible from the model browser as indicated on Figure below:

Model Browser Marine Growth type

The "Edit Marine Growth Profile Type" panel.

This panel is composed of the following items:

  • Two classical fields at the top of the panel to allow giving the name of the object and selecting other similar objects in the drop-down box
  • A "Marine Growth Properties" section to indicate the marine growth density. Default value is 1025 kg/m3
  • A "Marine Growth Profile" section to define the profile of marine growth along the line as a function of either the line abscissa or the water depth. Depending on the option selected, the table header should be updated (see below)
  • A "Profile evolution" section to choose between a linear or a constant evolution (see below)
  • A drop down list to select an existing variation table, note that the table could have 2 or 8 columns, but first column has a unit of type LENGTH (m), and thee second column has a unit THICKNESS (m); only the variation tables of these types are visible in this list

Linear and constant marine growth profile example

A new tab called "Marine Growth" in the Generic Line Panel enables to choose or not an existing Marine Growth to add a defined Marine Growth to a line:

Generic Line Panel

It is also possible to add Marine Growth in a more global way to an Analysis, it can be selected as any other shape. Please note that only valid Marine Growth which has a Water Depth profile can be selected:

Analysis selection item dialog box

Doing so, the selected Marine Growth is visible in the Analysis:

Model Browser - Marine Growth defined for an alanysis

When a Marine Gowth is defined for an analysis, it affects all lines within this Analysis. Nonetheless, if a Marine Growth is defined for the Analysis and for a line within this Analysis, the line is only concerned with it own Marine Growth, not the one defined in the Analysis.