Heat shrink joints use a heat-shrinkable tube, which is typically made of cross-linked polyolefin or similar materials. The tube is designed to shrink when heat is applied, creating a tight seal around the cables. Strip the insulation from the ends of the cables to be joined . Heat shrink cable joints are used to connect and insulate cables, providing a secure and protected connection. The shrink tube provides an effective barrier against moisture, dust, chemicals, and physical damage, ensuring cables and components are secure and safe from exposure. Common. 3M Heat Shrink is a trusted technology to reliably insulate and protect your important applications.