cryogenic deep freeze boxes

[bobc]

i am looking for design information on large liquid nitrogen cryogenic deep freeze boxes used in the heat treatment of large steel forgings.
my main concern is the system used to transfer the temperature of the LN2 to the forgings in the container.
it doesn't seem practical to attempt to bathe the product in the liquid as can be done with small items, so i assume there is some type of heat exchanging system.
am i correct in this line of thinking?
my product can exceed 40 tons and 30 ft in length with diameters to 80 in.
any assistance in locating relevant sites is greatly appreciated.
bob creely

 

[randi]

Try any of the ship approval agency of your choice they are always working with the approval of the cryogenic fluid bulk carriers as well as the industry where these are used. Here are some names - you could go to their technical assistance department:

LLoyd Register of Shipping - LRS
Bureau Veritas - BV
Det Norske Veritas - DNV
NKK of Japan
American Bureau of Shipping

or
Mitsubishi Heavy Industries - MHI
Cryogenic Engineering in US

 

[Frederick]

It really depends on what your final goal is. Research indicates that it is the gradual changes in temperature along with the hold time that gives some of the better wear resistance to metals through cryogenic processing. If you are simply trying to convert retained austenite to martensite, it is a different story.