As far as I know, perlite comes in powder form only, while min wool is in sheet form and suitable for wrapping round pipes - this cannot be done with perlite powder. Also, perlite powder is typically used in cold box insulation for low temperature / cryogenic operations. Presume you are looking to take advantage of the lower k value for perlite ? Also note that handling perlite powder for cold box top up operations can turn out to be an awfully messy operation, which isnt the case for min wool for pipe insulation.
This is a pretty basic question and I'm sure there are lots of information out there which can inform you better than we can.
in short - mineral wool is cheap, easy to fit but if it gets wet it can loose insulation and also act as a corrosion hot spot. With trace heating it can also get burnt at high temperatures over a long period of time and also needs an external barrier to hold it in place and prevent moisture ingress.
Perlite comes either as powder or granules and can be made into solid blocks or added to concrete to make insulating foundations.
There are many other forms of insulation, both solid foams and powder / granule types. Why are you just looking at two?
Remember - More details = better answers
Also: If you get a response it's polite to respond to it.
I feel this question is asked to me ha ha , yes, I have done enough in insulation . And yeah, absolutely right. Perlite comes in granule (usually preformed pipe sections/block forms). If your piping need to be heat traced, I would suggest to go for Mineral wool even though it increases probability to corrosion. But be sure to take precaution. Using perlite wont be handy if tracers need be incorporated. Because you need a higher dia perlite preformed sections to incorporate the trace pipes, and on making the installation robust and tight with the bands, the chances for perlite breakage is very likely. So just go ahead with Mineral wool, but before that be sure to wrap the whole pipe accommodating the trace pipe with Aluminium or SS foil (depending on the temp) to create annular space and maximum tracing efficiency. Also it helps in avoiding direct contact between Mineral wool and pipe.
