The climbers were roped together for 'safety'. = The climbers were roped together 'for safety's sake'.
There is 'safety in numbers'. [=you are safer in a group of people than you are when you are alone]
His hobbies act as a 'safety valve', relieving some of the pressure he feels from his job.
(..) you shall nose him as you go up the stairs - Go seek him there - He will stay till you come Hamlet, this deed of thine, for thine especial safety... Which we do tender as we dearly grieve for that which thou hast done ...must send thee hence with fiery quickness. Therefore prepare thyself (..)2015 Hamlet