DNV DNV-OS-F201 PDF

Scope and Application

This standard applies to all new built riser systems and may also be applied to modification, operation and upgrading of existing risers.

The scope covers design, materials, fabrication, testing, operation, maintenance and re-assessment of riser systems. Aspects relating to documentation, verification and quality control are also addressed. The main purpose is to cover design and analysis of top tensioned and compliant steel riser systems operated from floaters and fixed platforms. The standard applies for permanent operation (e.g. production and export/import of hydrocarbons and injection of fluids), as well as for temporary operation (e.g. drilling and completion/workover activities).

This standard is applicable to structural design of all pressure containing components that comprise the riser system, with special emphasis on:

— single pipes with a ratio of outside diameter to wall thickness less than 45;

— riser connectors and other riser components such as tension joints and stress joints.

Guidance note:

This standard may also be applied to design of single steel pipes used as components in more complex composite crosssections (e.g. umbilical) if the loading on the pipe can be adequately predicted.

Multitube cross-sections (i.e. pipes inside pipes) are not considered explicitly. However, this standard may be applied for design of each individual tubular of such cross-sections provided a realistic (conservative) distribution of the loading on each individual tubular are assumed. Boundary conditions of the pipes, temperature and local contact loads should be considered in particular.

There are, in principle, no limitations regarding floater type, water depth, riser application and configuration. However, for novel applications where experience is limited, special attention shall be given to identify possible new failure mechanisms, validity/adequacy of analysis methodology and new loads and load combinations.

Guidance note:

For application of this standard to new riser types/concepts (e.g. novel hybrid systems, complex riser bundles etc) it shall be documented that the global load effects can be predicted with same precision as for conventional riser systems. This may typically involve validation of computational methodology by physical testing.

As an alternative an appropriate conservatism in design should be documented.

Examples of typical floater and riser configurations are shown schematically in Figure 1-2. Examples of some typical components/important areas included in typical riser systems are illustrated in Figure 1-3.