Yes, it's fine.
You can take a look here.
Is this sentence correct?: " If a document is to be reviewed by more than one department, preferably only a single copy of the document should be circulated.
I don't understand if... is to be reviewed what is it grammatically? it is conditional, but is it correct like this?
Not only is it fine (Francois), it is correct.
The subject of the sentence (document) is a singular noun therefore the verb of the sentence (to be) must also be singular.