Design Options Body Flanges
The detail dimensions of the (body) flanges can be edited in the dialog window with tab 'Flange Thickness', see below figure.
Figure Design options flange thickness
The thickness including the confining depth can be set per flange. For the flange numbering refer to figure 'Flange numbering'. Flange numbers are per the TEMA code.
Not all numbers are present for all types of exchangers, for example flange 3 and 4 are not present in case of fixed tubesheets. In case of a BEM type flange number 1 will not exist.
Figure Flange numbering
- The flange thicknesses are optional because if left empty by the user the software will calculate the required thickness, including the thickness required for corrosion.
- If empty the number of bolts will be determined by the software. In case of an existing exchanger or user preference the number of bolts can be set as basis for the calculations.
- The entered flange thicknesses and number of bolts can be locked. When a new heat exchanger design cycle is performed the software will not change these values.
In case of an existing exchanger the thickness of the flange is usually set set as a basis for the calculations and will be locked. The values will not be changed by a design cycle.
The design cycle is executed by selecting in the menu:
View > Design & view construction sizes
The options from the menu View > Check & view construction sizes will only show the calculation values of the last design cycle and the optional values are not changed, even if they were not locked. Note: the floating head is not part of the flange numbering above.
The floating head and backing ring details are only applicable for exchangers with a floating head. The other type of exchangers will ignore the entered values in this section.
- The number of bolts can be entered by the user for the floating head. If left empty the software will determine the number of bolts when a design cycle is executed.
The number of bolts are determined by the software using good engineering practice. The basis of the design practice or procedure is as follows:
figure floating head design, cross sectional area and torque lever arm
The design cycle uses a fixed ratio for the floating head flange which is A : B = 1 : 2.5. Based on engineering experience this provides a good starting point for the design of the floating head flange. With this ratio the polar moment of inertia is almost equal for the same area.
The software will first start with a minimum bolt size form the TEMA code and will determine an initial value for the cross section area. From that point an iteration process will start and will increase the area dimensions in both directions such that the are ratio will remain around 1: 2.5. which is the most effective design considering the material weight.
The torque lever arm 'C' is determined during the iteration process. The area required for welding is taken in to account.
- The total height of the backing ring is indicated with D
- The thickness and confining of the floating head flange is indicated with B+E
- The thicknesses and number of bolts can be locked. This will prevent that the values will be changed during the design cycle of the heat exchanger.
The settings of the options can be printed by clicking the print button at the bottom of the options dialog window. A spreadsheet like overview will be shown which can be exported to an MSExcel spreadsheet or send to printer, refer to below figure 'Options print'.
Figure Options print
The design options overview is a reference document that can be used to quickly check the settings which were used during the design cycle. The various values are used in the calculations and are indicated again in the calculation were relevant.