4.8 PRODUCT PIPELINE PREPARATION
The discharge plan may require that some product pipelines be prepared
for discharge by flushing with the first product to be discharged. To
accomplish this, the chief officer must determine if the lines need
only be filled and drained, or if flushing is required.
In each case, the amount of higher-quality product used will be minimised
by thoroughly draining the line before flushing. The chief officer makes
up a written flushing plan which includes the necessary venting arrangement.
The plan should be reviewed by the master and communicated to the owners
and charterers for approval.
The tank designated to receive the flushings must be carefully checked
to verify that it can receive the flushings without contamination and
that it has an adequate ullage space to receive the flushing volume.
When the flushing plan has been approved, the valves are set according
to the plan. These procedures must be entered into the oil record book.
Fill and drain preparation
The stripping pump is used to transfer the content of the line to the
receiving tank. The receiving tank valves are then closed and the empty
pipeline is filled with the cargo from the first tank (high quality
cargo), on the discharge plan, venting air from the line during filling
to ensure that the pumproom riser is filled as high as possible. The
high-quality tank valve is closed and the pipeline is left to soak with
the new product. It is then stripped to the receiving tank. The line
is refilled from the high-quality tank. All valves are then closed until
arrival at the offloading dock.
All tank ullages before and after the line draining and flushing must
be recorded and a report of the operation attached to the ship's loading
If the line is to be flushed by pumping, it may be necessary to rig
a 'jumper' hose from the discharge manifold of the line being flushed
to the loading manifold of the tank receiving the flushings. The flushing
operation must be very carefully monitored, especially if the ullage
space in the receiving tank is limited.
The pipelines to be flushed should be stripped down first, to minimise
the potential for dead ends retaining product. After the valves are
set for the flush, the pump is started and run at moderate speed until
the desired volume has been pumped through the line.
Record all ullages before and after the flushing and attach a copy of
the flushing report to the loading port tank gauging report.