The design of the header box (the pressure-containing component where coolant enters) is critical. The 2024 edition has updated stress calculation methodologies, often aligning more closely with ASME Section VIII Division 1 and 2 pressure vessel codes. This ensures that the "nozzle loadings" (the forces exerted by connected piping) are calculated with higher precision, reducing the risk of flange leaks.
Until then, remains fully valid and accepted by most EPCs (Engineering, Procurement & Construction contractors). api 661 2024 pdf
