The hoop stress sh and the longitudinal stress sl are the principal stresses. For example; if a 500 inch diameter vessel is 90% filled with a fluid of density 0.0362lb/in³ and an over-pressure of 30psi is applied at the surface of the liquid, the maximum pressure at the top of the vessel will be 30psi whilst the maximum pressure at its base will be 46.29psi (46.29 = 90% x 500 x 0.0362 + 30) Since the vessel is under static equilibrium, it must satisfy Newton's first law of motion. When a pressure vessel is subjected to external pressure, the above formulas are still valid. A pressure vessel, as a type of unit, is one of the most important components in industrial and petrochemical process plants. In the broad sense, the term pressure vessel encompasses a wide range of unit heat exchangers, reactors, storage vessels, columns, separation vessels, etc. 10. The mechanism of external pressure failure is different from internal pressure failure. PDHonline Course M398 (3 PDH. if (document.getElementById("tester") != undefined) Note : What is the Difference Between the Design Formula of a Cylindrical Shell and a Spherical Shell? Towers, turbines, gearboxes; processes for shaping and finishing component parts. The ASME Boiler & Pressure Vessel Code (BPVC) is an American Society of Mechanical Engineers (ASME) standard that regulates the design and construction of boilers and pressure vessels.