Packaging for shipping compressed gas cylinders

The present invention pertains to packaging for storage cylinders designed for storing compressed gases, and in particular an apparatus and method for packaging cylinders containing compressed oxygen. An overpack is provided for packaging cylinders containing compressed gas. Cylinders containing compressed gas typically have a pressure relief mechanism that releases the gas from the cylinder when the pressure inside the cylinder approaches a pressure detrimental to the cylinder. In high heat, high temperature situations such as when the overpack is exposed to a fire, the overpack of the present invention extends the time that it takes for the cylinders to trigger the pressure relief mechanism.