Insulated pipe apparatus

An insulated pipe apparatus comprising:

• an inner conduit for carrying fluids;
• insulating material surrounding said inner conduit and extending substantially the length of said inner conduit;
• a rigid outer casing of a material resistant to mechanical stress and moisture ingress, coaxial and coextensive with said inner conduit and surrounding said insulating material;
• means defining a plurality of longitudinal elongated voids between said outer casing and said insulating material comprising a plurality of slots in the outer surface of said insulating material, said elongated voids being of substantially constant cross-section and coextensive with said insulating material;
• interconnecting means for interconnecting said elongated voids at each end of said insulated pipe apparatus comprising an annular void defined by the termination of at least a portion of said insulating material radially distal to said inner conduit proximate to the end of said rigid outer casing and the portion of said insulating material proximate to said inner conduit;
• means for sealing the ends of said insulated pipe apparatus between the outer surface of said inner conduit and said rigid outer casing;
• and
• coupling means for connecting said annular void to external equipment.