Category Archives for Process Design
External Pressure
Most vessels are designed to contain positive internal pressure, but it is possible to develop a partial vacuum inside of the vessel during steam-out cleaning, when draining liquids, or during abnormal process conditions. Therefore, it is general practice to check … Continue reading
Design Pressure: ASME Code, Section VIII, Division 2
Under Division 2, the pressures used for the design of each component are very similar to those discussed for Division 1, although terminology differs. The maximum pressure permissible at the top of the vessel at the design temperature is defined … Continue reading
Calculation of Maximum Allowable Working Pressure
The actual thicknesses of the various vessel components will usually be thicker than the thickness calculated using the component design pressure (P). It is usually more economic to obtain the required thickness plus corrosion allowance by purchasing the next thicker … Continue reading
Pressure Drop
The process design may indicate a large pressure drop (DP) through the vessel that should be considered in the design of each vessel component. If DP is significant, it should be added to establish the component design pressure (P):
Design Pressure and Pressure Used for Design of Individual Components
Although the design pressure (Pd) establishes the basis for the design of a vessel, it is not always the pressure used for designing components of the vessel. The pressure at the bottom of a vessel containing a liquid is higher … Continue reading
Design Pressure and Operating Pressure
The maximum operating pressure (Po), specified by process design engineers, is the maximum internal pressure that will occur under normal process conditions. The design pressure (Pd) is determined by adding a margin to the maximum operating pressure (Po) to allow … Continue reading
Maximum Allowable Working Pressure
The maximum allowable working pressure (MAWP) is required to be displayed on a pressure vessel’s nameplate, and is defined in the Code as, “the maximum pressure permissible at the top of the vessel in its normal operating position at the … Continue reading
Design Pressure
The following pressures must be considered in the design of a pressure vessel: • Operating pressure • Design pressure • Maximum allowable working pressure (MAWP) Figure 400-1 shows a typical pressure vessel with the pressures that must be considered, and … Continue reading
Determining Design Conditions
The following design conditions for a pressure vessel must be established before the actual design begins: • Design pressure • Design temperature • Wind and earthquake loads • Corrosion allowance • External loads • Internal loads Pressure and temperature are … Continue reading
Conical Heads and Transitions Subjected to External Pressure
Experimental research that compares conical and cylindrical shells has shown that the buckling of a conical shell is similar to that of a cylindrical shell with a length equal to the slant length of the cone and an outside diameter … Continue reading