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Pig launcher and receiver

Pig launchers and pig receivers are installed on a pipeline to launch and receive pipeline pigs and pipeline inspection tools.
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Piping system must be designed in the way that connecting pipes will not over-stress launcher or receiver. Let’s start from pig launcher supports. The first support has holes that fit bolts, but the second support has slotted holes that will provide free thermal expansion for the launcher itself. Since the first support is fixed, pipeline thermal expansion will imposed thermal force on the pig launcher. The pig launcher and receiver must be arranged in relation to a pipeline in such way that thermal expansion force from pipeline is minimal. Please see the the figure below.
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In the arrangement shown above, the underground pipe will be anchored by the virtual anchor that is result of soil friction. Pipeline flexibility is achieved by having elbow, allowing free thermal expansion in the direction perpendicular and parallel to launcher. If this arrangement is not suitable for your application, pig launcher can be set in direction of pipeline. Please see the figure below.
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Usually, this type of arrangement will require a concrete stop block to limit pipeline thermal expansion. Only stress analysis conducted on underground pipeline can determine requirement for the stop block. In the case that stop block is used, it must be sized in such way that resisting soil pressure does not exceed allowable soil pressure. Please see the figure below.
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Normally, comprehensive stress analysis using Caesar II (or Autopipe) is required, since high stresses are expected. Note that underground piping stress analysis has been discussed in my blog Buried pipe. Pig launcher stress can be obtained by Caesar II and it can be easily modelled, since the pig launcher is just big pipe having reducer. Most common launcher configuration is shown in the figure below.
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However, configuration shown in the figures above might not be always the case, since the project that I was working on, has the main pipeline coming vertically off the rack. Please see the figure below.
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Typical pig launcher PID can be found on Enggcyclopedia site (link).