Page 83 - Pipeline Pigging Technology

Pipeline Pigging Technology

(d) note that special attention should be paid to pipelines with a high
deposit drop-out rate, putting a time restraint on the cleaning/inspection
sequence (injection of chemicals may be considered);
(e) weather - or production - windows may form a constraint due to:
- shipping the tools offshore;
- high product temperature in summer exceeding inspection
equipment specifications;
- low product temperature in winter increasing deposit formation
(cloud or pour point);
- high demand of product exceeding maximum speed levels of inspec-
tion tools (over 4m/sec);
- low demand of product giving insufficient flow to run the inspection
tool (under 0.5m/sec). On long pipelines, even the battery capacity
may be exceeded due to long running time (exceeding 4 days);
(f) provide complete pipeline data including:
- historical data (with relevant notes on construction activities, e.g. left
the line full of water for two years, and operational changes, e.g.
initial low-flow conditions, increase of water cut three years ago,
etc.)
- relevant maintenance experience (e.g. cathodic protection system
failures, known corrosion, etc.)
- anticipated condition of the pipe wall
- pigging experience and results
- suggested pigging plan (specifying the level of detection and the
reporting format required)

Two simple rules are that time spent in the office is a lot cheaper than time
spent in the field, and overspending always attracts top management's
attention.
Although this discussion may appear very detailed, assessment of pigging
runs is a specialized job to be done by trained engineers. Instant decisions are
often required in order to determine the pig configuration for the next run.

CONCLUSION

This paper has the aim of sharing the author's pigging experience,
achieved from many pipeline pigging operations, with professional engineers
required to deal with a variety of different pipelines. It is hoped that the ideas

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