https://gamesartist.co.uk/modular-structures-kit/
3D Artist, Feydi Montassar has created these awesome modular prop kits, including pipes, electricity poles, stairs & vents, find out his workflow for these assets in this article, where he talks about, goals, software, ref, blockout, modelling, UVing, texturing, lighting & rendering.
https://www.artstation.com/montassar-faidi
https://www.artstation.com/artwork/qQyvZR