It's very similar in the natural gas industry. The "dumb" pigs are a piece of foam that is shoved into the pipe at the "pig launcher" and they use air pressure to push the pig through the pipe, where it is then caught in the "pig catcher". All the debris from fabrication of the pipeline is scrubbed out by the pig and removed at the pig catcher.

Nowadays, they also have "smart pigs" that have sensors to detect gouges, dents, pipe wall that is too thin, etc. as the pig moves through the pipe, so that repairs can be made before the pipeline is filled with gas.