Testing of Vacuum Jacketed Pipe		Pipe in Production

U.S. Bellows, Inc. recently custom designed and manufactured a vacuum jacketed pipe for transportation of liquefied natural gas.  This product consists of two pipes, the inner pipe is 304L stainless steel and the outer pipe is carbon steel. The inner pipe is wrapped with laminar radiation shielding to minimize radiation heat transfer from the jacket to the inner pipe. A chemical gathering system is also placed inside the annular space to remove vacuum contaminants released by out-gassing.

A bellows type expansion joint is installed in the outer jacket to compensate for the differential expansion between the inner pipe and jacket pipe. The support system is designed to absorb thermal loads on the inner pipe to minimize heat leakage. These supports allow axial movement of the inner pipe during contraction while disallowing any lateral movement. The spool piece is equipped with vacuum gauge and vacuum pump-out connections.