Chapter 6 - Tracking A Moving Pig; Using The Cd42 To "Leapfrog - CDI CD42 Instruction Manual

CD42 Pipeline Pig Location & Tracking System

Chapter 6 - Tracking a Moving Pig

Using the CD42 to "Leapfrog"

In order to have a general idea of the pig‟s vicinity, it is a good idea to leapfrog the pig as it traverses
the pipeline. If the pig becomes stuck, the operator can backtrack to the last known good passage
location by walking the pipeline and looking for transmitter pulses using the CD42-R receiver.
The operator should have a rough idea of the flow rate of the pipeline, and allow enough time between
points to set up the equipment and begin looking for the pig. When an operator sets up the CD42-R at a
location to await a pig passage, he should orient the receiving antenna parallel to the pipeline. As the
pig approaches the location and then moves away, it produces a distinctive wave shape on the display.
Figure 79 is an example of a typical pig passage.
Figure 79 Signal Of Approaching Pig
After the operator has identified a pig passage, he should then move immediately to the next leapfrog
point. If the pig passes the leapfrog point before the operator arrives and has the equipment set up, then
the operator may quickly lose track of the pig. This may cause much more time to be spent locating the
pig if it does become stuck.
In order to leapfrog properly, the operator needs to locate the leapfrogging points on the pipeline as
close together as possible. This will minimize the distance the operator will have to walk to locate a
stuck pig.
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