PURPOSE: To obtain a cryogenic valve for controlling the flow of a cryogenic fluid with very low heat leak, excellent strength, pressure or vacuum integrity and modest manufacturing cost.

CONSTITUTION: A bonnet extension 20 includes a thin-wall stainless-steel-made bellows 38, top covering wrapping 40 consisting of fiber filament and epoxy resin, and terminal members 42 and 44. Each member is independently welded with a valve body 14 and a bonnet assembly 16. The bonnet extension 20 is surrounded by a relatively thick layer 46 of an insulative material. This layer 46 is a composite insulative layer made typically by alternately laminating a material of high reflectance against thermal radiation and a material of very small thermal conductivity. This composite insulative layer is then surrounded in a vacuum jacket 48. The closest end to the valve body 14 is usually connected with a housing surrounding the valve body 14 and a passage 12.