[Mohammed]

Surface Tie Back System

Surface tie back are systems of special connectors and casing for extending the well casing from a mudline suspension system to a surface completion.

[Mohammed]

@Henry: Great!

• This reply was modified 4 years, 12 months ago by Mohammed.

[Mohammed]

Random Wave Analysis

Statistical analysis is done on the basis of a wave scatter diagram for the location of the offshore platform. Appropriate wave spectra are defined to perform the analysis in frequency domain. Random waves are also generated by appropriate wave spectra; if dynamic analyses analysis for extreme wave loadings are required for deepwater strcutures.

[Mohammed]

Offshore Jackup Rigs Engineering Design for Accidental Loads : Design Against Fire

Design against fire requires the following information

I. Fire scenerio i.e. Types (Pool fire or Jet fire), Location, Size, Intensity & Duration
II. Heat Flow Characteristics
III.Properties of steel at elevated temperature such as mechanical and thermal properties.
IV. Properties of fire protection.

• This reply was modified 4 years, 12 months ago by Mohammed.

[Mohammed]

Offshore Jackup Rigs Engineering Design for Accidental Loads : Segregation of Zones

Identify Zones of Different safety Levels

I. Process Zones: area with hydrocarbon equipment
II. Living Zones: areas where living facilities are located
III.Utility Zones: areas where utility non hydrocarbon equipment are located.

• This reply was modified 4 years, 12 months ago by Mohammed.

[Mohammed]

Offshore Jackup Rigs Engineering Design for Accidental Loads : Sources of Fire

I. Hydrocarbon Direct Fire (i.e. Fuel, Ignition and Oxygen).
II. Blast Initiated Fire.
III.Collission Initiated Fire.
IV. Dropped Object Initiated Fire.
V. Select materials such that the ultimate tensile strenght is higher than the yield strenght to avoid rupture to occur at first yield eben if the
fracture toughness is high.

• This reply was modified 4 years, 12 months ago by Mohammed.

[Mohammed]

Indirect Design

Energy absorption requires the structure to behave in a ductile manner. Mesures to obtain adequate ductility are

I. Provide connections of primary members with strength exceeding that of the parent member.
II. Provide redundancy in the structure such that alternate load distribution may be developed.
III.Avoid dependence on energy adsoption in struts with a sharply decreasing post buckling capacity.
IV. Select materials with sufficient fracture toughness properties.
V. Select materials such that the ultimate tensile strenght is higher than the yield strenght to avoid rupture to occur at first yield eben if the
fracture toughness is high.
VI. Design joints and members to maintain their capacity through substantial concentrated inelastic deformation, to meet compact section
requirement.

[Mohammed]

Leg Design

Design of legs involve the following steps:

I. Estimation of wave and current induced loads either by global analysis based on maximum base shear method or maximum moment method.
II. Estimation of gravity loads and wind induced shear from the super structure.
III.Design of lattice truss by simplified method or by the global analysis and design of each lattice members.

[Mohammed]

Analysis of Jackups

Typical jackup analysis involves the following stages:

I. Identification of legs as simplified model as beam element with spring supports below soil and connected to the hull.
II. The hull can be modeled using plate or equivalent beam element.
III.Estimation of global environmental loads
IV. Estimation of gravity & operational loads
V. Global analysis using non-linear analysis to account for large displacements.

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