Mechanical Eng

There are appearance issues to address. Other than that, yes.

Isn't there the risk of corrosion?

You could investigate plastic flanges.

There is always a risk of corrosion, both inside the pipe and outside it. Given the similarity between the metals that are to be connected, galvanic corrosion is likely to be of minor concern in comparison with the risk of attack on the MS flange from species outside the pipe. Mild steel is still used extensively for chilled water applications. The original poster hasn't given any indication as to whether the risk of corrosion is an issue for this particular installation.

Some plastics tend to increase their brittleness with lowering temperatures, and the original poster hasn't stated whether there is any significant mechanical risks associated with the installation that might obviate the use of plastics at this time.

So local judgement prevails for the moment!