I have looked endlesly for engeneering 3D models to have standarised pipe fittings. As I found none, or at least none thet were printable I made my own fittings.
This are 1 Inch and 3/4 Inch male/Female pipe fittings and should work with any industrial pipes, the fit might be a little loose/tight, but that can be adjusted by resising the model a bit to fit whatever youre building.
Feel free to use and modify this fittings in order to create whatever complex models or machines you wish, just be sure to thank or mention me if these helped.
I have built each piece sepparatly but should also work fine as a bundle. No raft nor supports nessesary