Vacuum Jacketed Piping

vacuum jacketed piping (VJP) is a dual-pipe system with an inner carrier pipe for supercooled cryogenic liquids like liquid nitrogen (-320°F or -196°C) and an outer jacket with an evacuated space to eliminate heat transfer. 

 Inner Pipe: Carries the cryogenic liquid nitrogen and is usually made of 300-series stainless steel designed for extreme cold.

Annular Space: The gap between the inner and outer pipes where air is evacuated to form a high-vacuum thermal barrier (often below 10⁻⁴ torr)

Super-Insulation: Multiple layers of reflective radiation foil wrapped around the inner pipe to block radiant heat transfer

Outer Jacket: A protective outer metal shell that maintains the vacuum seal and supports the entire assembly.

Installation and Assembly Steps:

• Alignment and Positioning: Place the dual-wall sections according to engineering drawings and slip a protective outer sleeve or coupling over the joint area.

• Inner Weld: Weld the inner flow pipes together first and complete required non-destructive testing or inspections.

• Jacket Closure:  Slide the outer sleeve over the welded inner joint, making sure any vacuum or fill nozzles face upward.

• Outer Weld: Fully weld the girth seams on both sides of the outer sleeve to seal the outer jacket.

• Evacuation and Sealing:Evacuate the annular space or seal the system depending on whether it is a dynamic or factory-sealed setup.