What surface preparation is required?

This depends on the pipe material.

For the very best results the seal should be fitted directly to the pipe wall. If the pipe is coated this, ideally, should first be removed. If the pipe coatings cannot be removed then the seal may be compromised because this would leave a potential leak path behind the coating.

After fitting, any removed coatings can be replaced with a variety of paints or screeds.
If the pipe material is steel or iron, then a suitable anticorrosive system will be agreed before the contract commences.

If the pipeline carries drinking water, then the protective coatings will be WRc or DWI approved, and agreed in advance.