Page 358 - Pipelines and Risers

Pipehe Inspection, Maintenance and Repair 329

b. Ensure that the launcher has been correctly isolated, depressurized, vented and purged and
is safe to open and ready to receive pigs;

C. Ensure that all valves on the pig route are or will be fully open;

d. Ensure that all pig indicators are correctly set and operational;

e. Inform the receiving station of the following:

pig type;
by-pass setting (that is, the pig has a by-pass facility in the case that the pressure build
behind the pig is too great)
time of launch;
estimated time of pig amval;
inlet I outlet flow conditions at time of launch.

f. Keep track of the pig run by continuously monitoring the pressure and flow conditions at
inlet and outlet. Remain in regular contact with the receiving station and exchange updates
on estimated time of pig arrival.

€5 Receiver station to notify launcher station when pig arrives in receiver and then isolate,
depressurize, vent and purge receiver prior to removal of pig and inspection for damage
and wear.

Data Monitoring
Each pig run shall be evaluated to determine the effectiveness of the operation. This
information shall be used to enable a proper decision for future pigging runs and/or any other
action to be taken. Typically, the following shall be evaluated.

- The actual pig amval time compared with the estimated arrival time. In conjunction with
known flow rates and associated flow conditions throughout the pigging run, an estimate
of pig by-passlpig slippage can reasonably be made;
- The wear on the pigs shall be determined and classified;
- The total weight of the debris received in the pig trap shall be measured. A sample shall
also be taken for subsequent analysis;
- An estimation of the water volume swept ahead of the pig should be made if suitable
equipment is available at the receiver station.

18.1.4 Pipeline Shutdown
A pipeline shutdown can be initiated in the following three circumstances: