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Last Updated: 2020.6

(Fixed, Floating, and U-Tube)

The conditions grid is a repository for tubesheet design cases. Values entered here will overrule values entered on previous tabs. For example, if shell pressure on this tab is 15 PSI and shell pressure on the shell tab is 50 PSI, 15 PSI will be used in the calculations; however, a value entered on the conditions grid will not change the value on any other tab.

The values entered on this tab default based on settings from other tabs. If temperatures, pressures, or materials are changed on the other tabs, the values on this tab will update even if they were manually changedonly reflect those changes for new rows that are added. If the values on this grid are manually changed, they will remain the same until a change on another tab or a manual adjustment occurs.not be updated by changes to the other tabs. 

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Shell Pressure: The shell side internal design pressure for Design Cases. This may be an operating pressure for the other thermal cases (e.g., Operating, Startup, Shutdown, etc).

Shell Vacuum: The shell side external design pressure for Design Cases. This may be an operating external pressure for the other thermal cases (e.g., Operating, Startup, Shutdown, etc).

Shell T_s: The shell material maximum mean metal design temperature for Design Cases. This may be an operating temperature for the other thermal cases (e.g., Operating, Startup, Shutdown, etc).  This temperature is used to determine the shell material properties for the row under consideration, with the exception of the alpha values.  It is conservative to use a higher value here and this will typically match the design temperature for the shell side, though the operating temp may be used in the thermal cases as mentioned.

Shell T_sm: The mean shell temperature along the shell length as expected during the case under consideration (e.g., Operating, Startup, Shutdown, etc). It is generally not conservative to substitute the shell design temperature for T_sm as a higher delta between T_sm and T_tm is what is considered conservative.

Shell T'_s: The metal temperature of the shell at the tubesheet rim as expected during the case under consideration (e.g., Operating, Startup, Shutdown, etc). It is usually not conservative to substitute the shell design temperature for T'_s. This value is only required for radial differential thermal expansion calculations.

Tube Pressure: The tube side internal design pressure for Design Cases. This may be an operating pressure for the other thermal cases (e.g., Operating, Startup, Shutdown, etc).

Tube Vacuum: The tube side external design pressure for Design Cases. This may be an operating external pressure for pressure for the other thermal cases (e.g., Operating, Startup, Shutdown, etc).

Tube T_t: The tube material maximum mean metal design temperature for Design Cases. This may be an operating temperature for the other thermal cases (e.g., Operating, Startup, Shutdown, etc).  This temperature is used to determine the tube and channel material properties for the row under consideration, with the exception of the alpha values and the tube values @ T_ts.  It is conservative to use a higher value here and this will typically match the design temperature for the tube side, though the operating temp may be used in some cases as mentioned.

Tube T_tm: The mean tube temperature along the tube length as expected during the case under consideration (e.g., Operating, Startup, Shutdown, etc); this considers the entire tube bundle. It is generally not conservative to substitute the tube design temperature for T_tm as a higher delta between T_sm and T_tm is what is considered conservative.

T'_c: The metal temperature of the channel at the tubesheet rim as expected during the case under consideration (e.g., Operating, Startup, Shutdown, etc). It is generally not conservative to substitute the channel design temperature for T'_c. This value is only required for radial differential thermal expansion calculations.

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Alpha: The material mean coefficient of thermal expansion based on the TE tables from Section II, Part D; column B is used in those tables. There are several materials that do not have clear matches in these tables. When a clear match cannot be found by the software’s assignment criteria, this value will be zero. Shell Alpha_s,m and Shell Band Alpha_s,m1 are based on T_sm. Shell Alpha' s is based on T'_s. Tube Alpha_st,m is based on T_tm. Stationary Channel Alpha'_c and Floating Channel Alpha'_c are based on T'_c. Tubesheet Alpha’ is based on T’.

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