| Eighty foot sections of pipe (especially
the large 36 inch and 42 inch types that carry petrochemical products) have
to be bent to follow the terrain when a pipeline is laid out. To prevent
buckling of the pipe during bending operations a “mandrel” is
inserted into the pipe and wedges itself under hydraulic control. The picture
below shows a bending machine with a mandrel sitting partly exposed in a
cut section of a 36 inch diameter pipe.
Until recently control of the mandrel and locating its whereabouts
within the pipe was a decidedly manual operation. Indus helped a
client (CRC-EVANS,
Houston, TX) develop a device for untethered position detection
and remote control of the mandrel. The position detection is done
by sensing the phase shift of a low frequency signal transmitted
through the pipe wall. A transmit coil is mounted on the bender
outside the pipe and a set of orthogonal receiver coils is mounted
on the mandrel inside the pipe. Remote control is achieved with
a pair of 900MHz spread spectrum radio modems.
The final device has undergone extensive field testing (several hundred
kilometers of pipe) in Canada and is being used in the Alliance Pipeline
project. A patent application for the device is pending.
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