Board Thread:Warhammer 40k General Discussion/@comment-72.240.130.242-20130618172401/@comment-8881468-20130619084425

it would not only be a question of warp capable engines, as you would need  inertia control, ways to keep the crew alive and engines to overcome planetary gravity, which in itself would make it quite the challenge and make the titans even more cumbersome and bigger targets, than they are.

as for titan deployment: I think "Galaxy in Flames" of the heresy series has the same text on massive landers

as for preparation of titans, see f.e. space marine shooter game in the latter stages we get some dialogue on it.

As for taking apart the machine:it takes months, iof not years to built anyhting of some size in the Imperium, if the machine spirit is activated and "alive" would you really, in the eyes of the tech priests, shut it down and tear it limb from limb, only to anger that AI?