Page 490 - Pipelines and Risers

Pipe-in-Pipe and Bundle Systems 457

Hydrotesting of the completed flowlines and subsequent leak testing of the sleeve and carrier
pipes,
Launch after tie-in of the towheads,
Tow from fabrication site to the field,
Installation at the designated infield locations,
Flooding of the bundle flowlines and carrier pipe with subsequent hydrotesting of the
flow lines.

Operational Phase Loads
The operational phase loads to be addressed as part of the flowline analyses are summarized
below:

Hydrostatic collapse of flowlines considering axial tensions and support conditions.
Expansion loading during operation, considering thermal and pressure induced forces, support
conditions within the carrier pipe and sleeve pipe and carrier free spanning.
Stability of the bundles, considering environmental forces during extreme wave events,
operational conditions within the flowlines and residual bundle curvature/displacement
present after installation.

Carrier expansion considering existing operational conditions within the bundle, including
thermaVpressure induced loads, residual installation curvaturddisplacement of the carrier and
possible free spans.
Additionally, where a sleeved pipe insulation system is present within the bundle, the effect of
thermaupressure effects upon the integrity of the sleeve and associated insulation bulkheads
will be evaluated.

Load Combinations
The most onerous of the following loading conditions shall be applied to the bundle design.
Functional loads alone.
Functional loads plus simultaneous environmental loading.
Accidental loads.

Functional loads are described as all loads arising from the flowline bundle system normal
function and include in addition the loads imposed during launch and installation.

Environmental loading is usually direct loading resulting from wave, wind or current but may
also include indirect loads, due to the environment, which are transmitted to the bundle
system during installation.