The required relief valve orifice area can be determined using the API 520/521 equations, which take into account the valve’s flow coefficient, the relieving pressure, and the required flow rate. The orifice area is typically calculated using the following equation: A = Q / (CKP), where A is the orifice area, Q is the required flow rate, C is the flow coefficient, K is the valve’s discharge coefficient, and P is the relieving pressure.