If the operating temperature range of the qualified work zone is equal
to or less than 170ºC (305ºF) then only one temperature within the operating temperature range is
required to be tested. If the operating temperature range of the qualified work zone is greater than 170ºC
(305ºF) then the minimum and maximum temperatures of the operating temperature range shall be tested.
For aluminum heat treating, a tighter temperature range is given in Process Table C, C2.4.