Our static vacuum-jacketed (VJ) piping has double-wall construction, with an inner pipe for the liquid nitrogen and an outer pipe to support and retain the vacuum insulation, both made of stainless steel. The insulation is a low-vacuum cavity with multiple layers of foil (super insulation) applied to reflect back radiant heat. Molecular sieves and getters are used with the insulation system to maintain low vacuum levels (9 microns or less) for many years.