AdvancePipeliner

The best established code for defining pipeline classes is DNV-OS-F101. Other codes follow simpler approaches to define classes. According to DNV-OS-F101 the following classes should be well defined prior to performing any analysis to the pipeline. Classification of fluid;

1. Category A, Typical non-flammable water based fluids.
2. Category B, Flammable and/or toxic fluids which are liquids at ambient temperature and atmospheric pressure conditions. Typical examples are oil and petruleum products. Methanol.
3. Category C, Non-flammable fluids which are non-toxic gases at ambient temperature and atmospheric pressure conditions. Typical examples are nitrogen, carbon dioxide, argon and air.
4. Category D, Non-toxi, single phase natural gas.
5. Category E, Flammable and/or toxic fluids which are gases at ambient temperature and atmospheric pressure conditions and which are conveys as gases an/or liquids. typical example would be hydrogen, natural gas (not otherwise covered under category D), ethane, ethylene, liquefied petroleum gas (such as propane and butane), natural gas liquids, ammonia, and chlorine.

Location classes;

1. Location 1, The are when no frequent human activity is anticipated along the pipeline route. Normally known as Zone I.
2. Location 2, The part of the pipeline/riser in the near platform area or in areas with frequent human activity. The extend of location Class 2 should be based on appropriate risk analysis. If no such analysis is performed a minimum distance of 500 m shall be adopted. This area normally known as Zone II.

Safety class (based on failure probability);

1. Low, Where failure implies low risk of human injury and minor environmental and economic consequences. This is the usual classification for installation phase.
2. Medium, For temporary conditions where failure implies risk of human injury, significant environmental pollutions or very high economic or political consequences. this is the usual classification for operation outside the platform area (Zone I).
3. High, For operation conditions where failure probability implies high risk of human injury, significant environmental pollution or very high economic or political consequences. This is the usual classification during operation in location class 2 (Zone II).

Safety classes can be normally related to fluid classes and location classes as follows;

1. For Category A and C fluids in Location Class 1, Safety Class is always low.
2. For Category A and C fluids in Location Class 2, Safety Class is low in temporary phases (installation and pre-commissioning) and medium in operational phases.
3. For other fluids in all location classes, safety class is low in installation phase.
4. For other fluids in Location Class 1, safety class is medium in pre commissioning and operation phases.
5. For other fluids in Location Class 2, safety class is high in pre commissioning and operation phases.

References: DNV-OS-F101, Submarine Pipeline Systems, October 2006.