Abstract -- An
autoclave is provided for heat treatment of a load whose
position relative to the autoclave, whose cross-section
and/or whose thermal characteristics may vary along the
load, e.g. large panels for an airliner. The autoclave
comprises a chamber for receiving the load, a wall of said
chamber providing one end thereof and a door providing the
other end of the chamber and giving access for insertion and
removal of the load. Means is provided for heating gas in
the chamber, and a plurality of gas circulation means are
provided spaced along the length of the autoclave and each
producing a zone for circulation of heating gas. Means is
provided for independent control of the rate of heat
transfer between the heating gas and the load in said zones
and said gas circulation means is arranged to produce a
pattern of circulation in which heating gas impinges
non-axially onto the load.