no not really. there's obviously a large o ring but I've reused these a few times with no issues. the breather and overflow pipes can be tight but they will just pull off with a good tug.
I took photos of the process before I sent a tank away to get painted. Two weeks later I looked at them before rebuilding. Wasn't really necessary but saves you having a bolt left at the end of a job and wondering WTF?
Done it on many strip down and rebuilds of machines.