Abstract
A series of of tests on the sealing characteristics of a number of gaskets and flanges against the superfluid helium below 2.17°K has been made. Commercially available aluminum Helicoflex with stainless steel and aluminum alloy flanges is tight to the normal liquid helium but leaks at the superfluid temperatures. However copper, silver and indium coated aluminum Helicoflex and Sureket (a gasket made of stainless steel tubing with silver coating) with stainless steel and aluminum alloy flanges are found to be tight to the superfluid helium.
