Pressure relief protection for vessel jackets in a fire scenario can present some difficult design problems. Venting of a two-phase mixture (due to high heat input, cross-sectional flow area, and contaminants) using the typical jacket relief device (pressure safety relief valve) can result in the design of a very large, expensive valve. Alternative methods for vessel jacket relief systems are presented, with the most novel approach using fusible plugs as supplemental protection in order to reduce the size requirements of a pressure safety relief valve. An example is used to compare the size requirements for various relief devices.