Dual wall thermally insulated conduit including skin effect heat tracing pipes

摘要

A dual wall thermally insulated conduit which is heat traced using skin effect pipes. A plurality of equally spaced skin effect pipes run longitudinally with the conduit and are located adjacent and external to the carrier or process pipe in the annular cavity between the process and sleeve or jacket pipes. Special joint connectors include holes in the yoke portion to allow the skin effect pipes to exit the annular cavity between the process and jacket pipes. A clam shell is fitted over the special joint connector after the pipe section is assembled and the return conductor installed. The cavity inside the clam shell is filled with insulation. Structural insulation is positioned at the ends of the clam shell to provide a smooth transition to the protective concrete weight coating conventionally used with subsea piping. In cases where the material being delivered has a relatively high desired minimum temperature, it is desirable to actually reduce the thickness of the annular cavity between the process and jacket conduits as the temperature differential between the center of the pipe and the pipe section joint is actually reduced to acceptable levels.