Closed heat-shrinkable sleeve, also known as round sleeve, round tubular heat-shrinkable sleeve or closed sleeve, is an anti-corrosive material made of radiation-cross-linked polyethylene pipe and special hot-melt adhesive. Compared with ordinary polyethylene, radiation-cross-linked modified polyethylene has higher mechanical strength and longer service life.Corrosion resistance, aging resistance, environmental stress cracking resistance.Composite hot melt adhesive has the characteristics of strong adhesion, good sealing and simple operation.Widely used in petroleum, natural gas, petrochemical, urban gas pipe network, thermal pipe, power, metallurgy, water supply and other engineering steel pipe mouth, wound, interface, winding anti-corrosion, as well as water supply and drainage, thermal insulation pipe project PE, PVC pipe street closed fixed.