Page 487 - Pipelines and Risers

454 Chapter 24

24.3.5 Functional Requirement
Design Pressure
The general design pressures for the bundle system shall be based on processing data. The
internal pressure for carrier and sleeve pipes during installation should be at least 1 bar higher
then the expected water depth.

Hydrotest Pressure
Hydrotest pressure of the flowlines, heat-up and service lines systems shall be based on
1.2xdesign pressure.

Design Temperature
Design temperature shall be based on the processing data. Significant temperature drop along
the bundle system must be avoided.

Pigging Requirements
If the bundle system is designed for pigging, the geometric requirement shall be fulfilled. The
minimum bend radius should be 5 times the nominal internal diameter of the pipe to be
pigged. The pipe shall be gauged as a part of onshore and offshore testing of the system.
24.3.6 Insulation and Heat-Up System
The following requirements related to insulation and heat-up functional requirement for the
bundle system shall be satisfied

During normal operation the temperature shall be above the hydrate formation
temperature for the system.
Minimum arrival temperature for the production lines shall be above hydrate formation
temperature.
A minimum of certain hours shutdown shall be accepted before the fluid in the production
lines has reached hydrate formation temperature.
To melt wax it shall be possible to bring temperature in the system up to above a certain
degree.

The cool down time is the critical factor to determine the bundle insulation requirements.
Therefore, the design of insulation thickness shall be based on the minimum cool down time.
The insulation combined with active heating shall fulfil the heat-up requirement where
applicable.
The following factors shall be considered for the bundle thermal design:

Maximum / minimum operating temperature
Cool down time
Heat-up time