Questions about carbon dioxide gas cylinders

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In my work, I encountered a situation where carbon dioxide cylinders were filled with liquid nitrogen dioxide. During the production process, these cylinders were heated using a water bath at a temperature of 40 degrees. What is the phase state of carbon dioxide inside the cylinders at this temperature: liquid, gas, or a mixture of both? The critical temperature of carbon dioxide is 31 degrees, and the critical pressure is a little over 7 MPa. My understanding is that when the heating temperature reaches 40 degrees, which is above the critical temperature of carbon dioxide, no pressure, no matter how high, can turn the carbon dioxide cylinder into a liquid state. The carbon dioxide inside the cylinder should be in gaseous form, and the pressure within the cylinder is very high; if the cylinder’s strength is insufficient, a physical explosion of the cylinder may occur. I hope the experts here can give me some advice. Thank you!