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Chapter 18

Pipeline Inspection, Maintenance and Repair

18.1 Operations

18.1.1 Operating Philosophy
A pipeline operations philosophy needs to be developed and incorporated into the Operations
Manual. The philosophy should address the overall issues that dictate gas operation such as:

Maximum and minimum design and operating limits on gas flowrate, pressure and
temperature;
Sales contract requirements;
Utilization of line pack to satisfy fluctuations in demand;
Gas delivery requirements at third party tie-ins;
Actions to be taken in the event of planned or unplanned shutdowns of the compressor
station, e.g. allow gas delivery to continue via line pack inventory until minimum delivery
pressure limits are reached;
Actions to be taken in the event of planned or unplanned shutdowns of the delivery
station, e.g. continue gas pumping until maximum pipeline pressure limits are reached.

18.1.2 Pipeline Security
Certain control systems must be provided so that the pipeline may be operated safely. The
following functions are the minimum to be provided.

Emergency Shutdown
A means of shutting down the pipeline must be provided at each of its initial and terminal
points. The emergency shut-down systems must be equipped so that any shut down will
register at the control center and a positive alarm system will draw the attention of the person
in charge of the control center to the event. The response time of an emergency shut down
(ESD) valve should be appropriate to the fluid in the pipeline (type and volume) and the
operating conditions.