Two workers were injured, one seriously, when a “pig” they were operating at a section of the nearly completed Mariner East 2 pipeline (near Pittsburgh, in Westmoreland County) accelerated and hit them late Sunday. What’s a pig? It stands for Pipeline Inspection Gauge–a device used inside a pipeline for cleaning, inspection and maintenance, and fluid batching. A pig is pushed along the inside of the pipeline by the flow of liquid or gas or (in this case), air. A pig launching station is used to insert the pig into a pipeline using a series of valves and hatches. The pig is pushed through the pipeline by the fluid/gas/air to the pig receiving station. We don’t have all the details for how this accident happened. What we know is that two workers, a man and a woman, were operating the pig when it hit them. Both were taken to the hospital. The woman was later released, but the man sustained a broken arm and is still hospitalized.