A station on a natural gas pipeline used for the loading and unloading of pipeline inspection gauges, commonly known as "pigs". Photographed near <a href="https://en.wikipedia.org/wiki/D%C3%BCbendorf,_Switzerland" class="extiw" title="en:Dübendorf, Switzerland">Dübendorf, Switzerland</a>.
<p>Additional annotations from the English Wikipedia by users <a href="https://en.wikipedia.org/wiki/User:Cadmium" class="extiw" title="en:User:Cadmium">Cadmium</a>, <a href="https://en.wikipedia.org/wiki/User:Mannings" class="extiw" title="en:User:Mannings">Mannings</a>, and <a href="https://en.wikipedia.org/wiki/User:BrutonD" class="extiw" title="en:User:BrutonD">BrutonD</a>:
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<i>This is station for loading or unloading <a href="https://en.wikipedia.org/wiki/Pipeline_inspection_gauge" class="extiw" title="en:Pipeline inspection gauge">pigs</a>, the pigs are used for cleaning out or inspecting pipelines. This station is designed to receive pigs from the upstream section and launch pigs into the downstream section, with a cross-over for the fluid to flow from one section to the next. The pre-installed thrust blocks (those empty concrete rectangles in front of the blank flanges) are to support a (temporary) pig-trap which is bolted on to the pipeline in place of the blind flange.  The pig-trap normally includes a section of larger diameter pipe to allow the pig to come to a gentle stop with flow passing around the pig. After closing the valves for isolation, the pig can be removed via a quick opening closure (like a flange) on the end of the pig-trap. The fact the pig-traps are not present means that this pipeline is not pigged regularly.</i>
<a href="//commons.wikimedia.org/wiki/User:Audriusa" title="User:Audriusa">Audriusa</a> (Audrius Meskauskas)
CC BY-SA 3.0
<span class="int-own-work" lang="en">Own work</span>