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A special range of pigs (pipe testing and cleaning
devices) containing TDS2020 embedded computers was developed for
Statoil, a major Norwegian pipeline company, by John Plank at D
W Ryan.
Statoil ASA is one of the world's largest net sellers of crude
oil, and a substantial supplier of natural gas to Europe. It is
the leading Scandinavian retailer of petrol and other oil products.
TDS2020 data logging modules were
inside a pressure vessel that had to withstand an external
pressure of 100 bar as they logged peak deflection data. |
Gas is produced from the Aasgard field, in the Norwegian sector
of the North Sea, and transported to Karsto Gas Treatment plant
near Haugesund. The pipeline is 700km long and 42 inches in
diameter, except for a short 500 metre section of 28 inch at
the riser base.
It is a standard requirement to "prove" a new pipeline,
normally by running a pig through the pipeline with an aluminium
gauging disc sized at 95% or 97% of the nominal bore. If the plate
comes through unscathed, it can be concluded that the pipeline
is free of significant dents, buckles or obstructions. In this
case, the 500m length of 28 inch diameter pipe precludes this simple
action, and also makes any pigging operation very difficult due
to the large change in diameter that any pig will have to negotiate.
It was therefore necessary to develop a range of pigs to prepare
the completed pipeline for gas transportation. The main criteria
for the pigs was to negotiate the large change in diameter and
still carry out their main functions, which were as follows;
l Swabbing
Pigs - to sweep the water out of the pipeline
l Magnetic
Cleaning Pigs - to pick up any welding and construction
debris
l Electronic
Gauging Pigs - to prove the diameter of the line.
The internal bore of the pipeline was gauged by measuring the deflection
of the rear suspension arms, using a linear displacement transducer.
The TDS2020 logging
engine was housed in a pressure vessel inside the pig body, capable
of withstanding an external pressure of 100 bar. Logging was initiated
by a pressure switch, activated when the pigs were launched.
The TDS2020 was
used to take readings at 33msec intervals, and the peak deflection
was recorded at one second intervals. Real time and peak deflection
data were transferred to an 8M bit Compact Flash card
for storage.
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CONTACTS for more information:
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