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.
(..) there's a risk to those aboard the Dauntless, which includes the future Mrs.Commodore. Sorry, but it's for your own safety. The commodore ordered! I have to tell him! The pirates! They're cursed! They can't be killed! (..)2003 Pirates of the Caribbean: The Curse of the Black Pearl