I’m familiar with cleaning pigs. The intelligent pigs have things like eddy current sensors to detect any defects such as corrosion and cracking.
I have also seen pigs used in pipelines for product separation. One pipeline where I did some terminal work handled gasoline (several grades), butane, and propane. I installed the custody transfer measurement systems.
I had no idea what running a pig meant. I looked it up and replied to you so others might save a minute or two. I have always been fascinated by engineering of all kinds.
My son sometimes talks about going to work in Oil and Gas. Where does one start?