Haven't thought about that for years.
Firstly. It's complicated. It's not easy to do it well.
If you want to steam sanitize something you have to remove all the air. Either by vaccuum or by adequate venting. Then you need to maintain pressure AND moisture levels (in tanks and pipelines). It is a pressure/temperature/humidity/time relationship
Adequate venting is difficult in a heat exchanger with live steam/condensate.
It can be helpful as an add on to CIP regimes. Effective SIP however relies on effective CIP. In a brewery, I would only resort to it if I had some sort of issue with infection. It is quite energy intensive and can be costly.
Clean steam is also an issue. It can be extremely aggressive on 304 stainless. If you have 316 stainless product surfaces it will be much less of an issue.
You are correct in wondering about gasket materials etc. Can't comment there.
I would suggest you google SIP systems and design concerns thereof.