Page 209 - Pipeline Pigging Technology

Pipeline Pigging Technology

internal inspection of the pipeline to verify its mechanical integrity.

BACKGROUND

The following were the primary reasons for the inspection:

Public safety - a need for AGEC to determine the line's mechanical
integrity given its concern for public safety.

Pipeline coating concerns - the pipeline is coated with double-wrap
polyethylene tape which is prone to disbondment. Disbondment is
difficult to detect, and corrosion under the disbonded coating is only
detectable with an internal inspection tool.

Polymer formation - during the life of the pipeline, maximum through-
put had decreased by 26%. This decreased capacity seriously af-
fected AGEC's product transfer capability such that it would force a
reduction in ethylene plant production under certain circumstances.
In order to perform an internal inspection, the pipeline polymer had
to be removed.

Project considerations

Because of the uncertainties associated with the internal polymer, coupled
with the requirement to evacuate the line to install additional pigging stations,
the actual cleaning and inspection was to take place coincident with an
ethylene plant maintenance shutdown. The pipeline was completely
decommissioned, with all pigging taking place in nitrogen. This not only
eliminated the risks associated with sticking a pig in ethylene service, but also
eliminated the prospect of inadvertently interrupting ethylene supply to
customers. The length of the project was set at 28 days, the time planned for
the ethylene plant turn-around.

PROJECT ORGANIZATION

To provide pigging experience, Novacorp was hired to engineer, procure
and construct the capital works and to clean and inspect the pipeline. AGEC

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