What is the primary purpose of warning yarns in a sling?

The primary purpose of warning yarns in a sling is to indicate wear and damage. These brightly colored yarns are woven into the sling and serve as a visual warning sign when the sling is experiencing excessive wear or has been damaged. When the sling shows signs of fraying or the warning yarns become exposed, it is a clear indication that the sling may no longer be safe for use and should be inspected or replaced. This feature is crucial for maintaining safety in rigging operations, as it helps prevent accidents that could result from using compromised equipment. The presence of warning yarns is a proactive safety measure designed to inform personnel about the condition of the sling before any potential failure occurs.