A 15 – 20° assembly bezel (insertion bevel) must always be provided to avoid damage when fitting the seal (see diagram). If possible, use assembly grease or oil. When doing so, check the resistance of the elastomer to the lubricant.

There must be no dirt or other residues in the seating groove or on the O-Ring.  The O-Ring must not be significantly distorted by rolling. There must not be any sharp edges, tool marks, threads or holes where the O-Ring is fitted.