This European Standard covers the general requirements for heat treatment facilities processing semi-finished products and parts in metallic aerospace materials. It defines the terms used herein and describes the test procedures and requirements for mandatory tests of heat treatment facilities. It also serves as an aid in the surveillance and approval of heat treatment facilities. This standard applies to all types of heat treatment facilities@ including those using direct or indirect heat transfer and liquid or gaseous heating media@ with our without circulation@ and to vacuum furnaces.