Page 30 - Pipelines and Risers

4 Chapter I

The primary objectives can be summarized as:

Route optimization;
Selection of wall thickness and coating;
Confirm code requirements on strength, Vortex-Induced Vibrations (VIV), on-bottom
stability, global buckling and installation;
Confirm the design andor perform additional design as defined in the preliminary
engineering;
Development of the design and drawings in sufficient detail for the subsea scope. This
may include pipelines, tie-ins, crossings, span corrections, risers, shore approaches, subsea
structures;
Prepare detailed alignment sheets based on most recent survey data;
Preparation of specifications, typically covering materials, cost applications, construction
activities (i.e. pipelay, survey, welding, riser installations, spoolpiece installation, subsea
tie-ins, subsea structure installation) and commissioning (i.e. flooding, pigging, hydrotest,
cleaning, drying);
Prepare material take off (h4TO) and compile necessary requisition information for the
procurement of materials;
Prepare design data and other information required for the certification authorities.
1.2.2 Design Process

The object of the design process for a pipeline is to determine, based on given operating
parameters, the optimum pipeline size parameters. These parameters include:

- Pipeline internal diameter;
- Pipeline wall thickness;
- Grade of pipeline material;
- Type of coating-corrosion and weight (if any);
- Coating wall thickness.

The design process required to optimize the pipeline size parameters is an iterative one and is
summarize in Figure 1.2. The design analysis is illustrated in Figure 1.3.