Page 41 - Pipeline Pigging Technology

Pipeline Pigging Technology

resulting data is fed into a PC, and the results can be shown on a VDU. Hard
copy can also be provided if required.
A major advantage of the electronic-mechanical method is the ability to
select any particular signal, or series of signals, and enlarge them. In this way,
the particular feature and its dimensions can be much more accurately
determined, often without the need for input from a skilled technician.

Electro-magnetic

The pioneer in this field is H.Rosen Engineering (HRE), a highly-innovative
company, who can claim a number of "firsts" in the field of ILL
The original HRE geometry pig had strain gauges mounted around its
circumference which, when deflected by a reduction, provided a signal to the
on-board data processor/storage unit. It was not long, however, before HRE
introduced its electro-magnetic "electronic gauging" pig or EGP (Fig.3). The
dome-shaped unit on the rear generates and radiates an electro-magnetic field
which, for all practical purposes, is only affected by the relative distance of
any ferrous material (i.e. the pipe wall). Changes in the field due to any
reductions in diameter of the pipe are converted to an electrical signal which
is processed and stored on board for subsequent down-loading into a portable
PC when the pig is received.
Preliminary results are available on site almost immediately, and hard copy
combined with a zoom capability to match the scale of available strip maps,
greatly simplifies reporting.
One major advantage of this system is that it does not require contact with
the pipe wall. This not only eliminates many mechanical problems but, as it
is capable of taking readings at a rate of 50 times per second, it also gives it a
very wide allowable speed range and inherently-robust qualities.
The geometry readings are taken by a number of individual sensors, each
being recorded on its own channel and so forming the basis for determining
the radial location of any features. Distance measurement is by odometer
wheel, and an additional channel provides a constant readout of the speed.

Alignment pigs

Gyroscopic

Perhaps not surprisingly, gyroscopes were among the first ideas to be tried
for determining the alignment of a pipeline. Drawing on the development

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