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.
(..) Yeah. I don't suppose you found a key lying around somewhere? Yeah. I did. So what's our play? - I'm here to get you to safety. - Job's not finished. We could help with the evacuation, but I can't be in a fight near civilians. And you've done plenty. Our fight is over. So we just disappear? (..)2015 Avengers: Age of Ultron