Replacing mounting flange on Pierburg 2e, silicon needed ?

As the title may suggest, I'm going for a flange replacement. While doing research I saw some chap using black silicone kit while doing the job. I haven't been able to find any mention of it on the forums here or elsewhere.

Can I assume it's just a matter of cleaning up the surfaces and installing ?

Thanks in advance.
 

I used a sealer on mine, just to be sure to be sure, but as long as you clean the surfaces you should be fine.