When it comes to archivists and conservators, if you ask them the one thing they wish people would stop using on paper and photographs they will most likely respond "DON'T USE TAPE FOR REPAIRS!"
Tape has a lot of great and helpful uses, but when it comes to preservation - non-archival tape can do some real damage.
If the pieces are completely separated, store them in an enclosed envelope to keep them together.
If it's just torn, you can add support with archival folder stock and limit direct handling with sleeves made from archival plastics.
If you use tape, stick to document repair tapes that are of archival quality. Archival adhesives won't yellow or turn brittle and can be reversed.