This document specifies requirements, design and test methods for factory made thermally insulated bonded valve assemblies for directly buried district cooling distribution systems, comprising a steel valve from DN 15 to DN 1200, rigid polyurethane foam insulation and a casing of polyethylene. The valve assembly can also include the following additional elements: measuring wires, spacers and diffusion barriers. This document applies only to insulated valve assemblies, for continuous operation with water at various temperatures (1 to 30) °C and a maximum operation pressure of 25 bar. The design is based on an expected service life with continuous operation of a minimum 50 years. NOTE – An expected service life of 50 years presupposes that treated water is used.