Use the Design Constraints Tab to set the default values for the entire vessel. Enter the pressures and temperatures in these first four fields. PV Elite uses these values as the default values for the whole vessel.
Some of the other design constraints to consider are discussed below.
Datum Line Options
-
Select the 3D View tab.
PV Elite locates the datum line at the tangent line of the bottom head. Change the location of the datum line at any time to move it to a more convenient location.
-
Select Browse
at the end of the Datum Line Options field.
-
Type 3 for the Vertical Vessels offset, and then select OK. This sets the datum line to 3 feet up from its current location.
After attaching a skirt to the bottom of the vessel, the datum line can be moved
to the bottom of the skirt.
Hydrotest Type and Position of the Hydrotest
Specifies the type of hydrostatic test. Options are specific to the selected Design Code.
Division 1
UG-99b
ASME UG-99 (b), Division 1. The hydrotest pressure is 1.3 times (1.5 for pre-99 addenda) the maximum allowable working pressure (MAWP) for the vessel multiplied by the lowest ratio of the stress value Sa for the test temperature to the stress value S for the design temperature. This type of hydrotest is normally used for non-carbon steel vessels for which the allowable stress changes with temperature, starting even at a somewhat low temperature.
UG-99c
ASME UG-99(c), Division 1. The hydrotest pressure is determined by multiplying the minimum value of the maximum allowable pressure (MAP) by 1.3 (1.5 for pre-99 addenda) and reducing this value by the hydrostatic head on that part. The hydrostatic head is calculated based on the dimensions of the vessel and by values for Projection from Top, Projection from Bottom, and Projection from Bottom Ope. In addition, Pressure Test Position is used to determine the head pressure.
UG-99b(35)
ASME UG-99(b), footnote 35, Division 1. The hydrotest pressure is 1.3 times (1.5 for pre-99 addenda) the design pressure for the entire vessel, multiplied by the lowest ratio of the stress value Sa for the test temperature to the stress value S for the design temperature.
UG-100
ASME UG-100 pneumatic test. The test pressure is 1.1 times (1.25 for pre-99 addenda) the maximum allowable working pressure (MAWP) for the entire vessel, multiplied by the lowest ratio of the stress value Sa for the test temperature to the stress value S for the design temperature.
The stress ratio mentioned above includes bolt allowable stresses for flanges that
are designed according to Appendix 2. This allowance usually results in a ratio of
1. See ASME Interpretation VIII-1-83-260 for more information. Select Tools > Configuration to turn off this option, resulting in a ratio greater than one in cases in which
the operating and ambient stresses for the vessel parts are not the same.
No Hydro
No hydrotest pressure.
PED
European Pressure Equipment Directive. The test pressure is the maximum of:
-
1.43 * design pressure
-
1.25 * design pressure * Sa/S
App. 27-4
ASME Appendix 27-4, Division 1. The hydrotest pressure is 1.3 times the maximum allowable working pressure (MAWP) for the vessel multiplied by the lowest ratio of the stress value Sa for the test temperature to the stress value S for the design temperature. This type of hydrotest is normally used for glass-lined vessels.
PED & UG99b(35)
The hydrotest pressure is the maximum of the PED and UG99b(35) values.
User Entered Pressure
User defined test pressure.
Division 2
Hydrostatic
Hydrotest pressure.
Pneumatic
Pneumatic test pressure.
No Hydro
No hydrotest pressure.
User Entered Pressure
User defined test pressure.
EN 13445, PD 5000, and AD 2000
Standard
Standard test pressure. The value is unique for each European code.
PED
European Pressure Equipment Directive. The test pressure is the maximum of:
-
1.43 * design pressure
-
1.25 * design pressure * Sa/S
None
-
No hydrotest pressure.
The next box lets you specify which position the vessel will be during the hydrotest:
Select a hydrotest position. This input is required so that the total static head can be determined and subtracted when UG-99c is selected for Pressure Test Type. This value is used in conjunction with Projection from Top, Projection from Bottom, and Flange Distance to Top to determine the total static head. Select from the following:
-
Vertical - The vessel is tested in the upright or vertical position. This is not common.
-
Horizontal - The vessel is tested in the horizontal position. This is common for most vessels. The vessel is on its side (in the case of a vertical vessel) or in its normal position (for a horizontal vessel).
Tall towers for example, are usually hydrotested in the horizontal position. PV Elite has to compute the hydrostatic pressure from the water in the vessel at hydrotest time. If the vessel is tested in the vertical positions, the pressure at the bottom of the vessel will be greater than if the vessel is tested in the horizontal position. Carefully consider the position that is appropriate to your situation.
Miscellaneous Weight %
Opens the Miscellaneous Weight Percent Inclusion dialog, which lets you increase the weight of vessel elements and details.
Application Method for Weight Percentage
Miscellaneous Weight Percentages
Circular Platform Uniform Weight
Design Code
PV Elite allows the user to perform vessel calculations in several pressure vessel codes. Use the Design Code field on the Home tab in the Units/Code panel to change the design code.
PV Elite supports the following design codes:
-
ASME Section VIII, Division 1
-
ASME Section VIII, Division 2
-
British Code PD 5500
-
European Code EN 13445
-
AD 2000
When you change the code on an existing model, reselect the materials because each code has its own design stress tables.
Is this a Heat Exchanger
If the Dimensional Solutions 3D file interface button is selected, also select this option to write geometry and loading information for this vessel design to the <jobname>.ini file created in the current working directory. See Dimensional Solutions for more information about the Dimensional Solutions product line. This entry is optional.
To completely define an exchanger it is necessary to enter in the required information
regarding the tubes, tubesheets and the floating head (if any). With the exchanger
data, PV Elite can then compute the weights and required thicknesses of the exchanger
components. For more information, see Tubesheet.
This check box is optional.
ASME Steel Stack
Select to perform an ASME steel stack analysis, based on the ASME recommended guidelines for Steel Stacks STS-1. This analysis is for circular stacks that meet the design requirements in the steel stack guidelines. The results are shown in the ASME STS Stack Calculations report. If Design Code is not set to Division 1 (ASME VIII-1), the stack analysis is not performed.
Also select this option if you are analyzing a steel stack and want to check it against ASME STS-1. After the software completes the calculation, the program generates the Stress Due to Combined Loads report with a listing of the stack calculations. Compressive allowables in the report are calculated based on Section 4.4.
When selected, expand ASME Steel Stack and enter values for ASCE Wind Exposure, Factor of Safety, Mean Hourly Wind Speed, Is the Stack Lined?, and Importance Factor.
Read and understand the ASME stack guidelines. This is not a code like ASME Division
1 or 2, but a set of design guidelines for designers and engineers.
The following paragraphs from the stack guidelines are addressed:
-
4.4 Allowable Stresses
-
4.4.1 Longitudinal Compression, equations 4.7,4.8 and 4.9
-
4.4.2 Longitudinal Compression and Bending
-
4.4.3 Circumferential Stresses
-
4.4.4 Combined Longitudinal and Circumferential Compressive Stresses
-
4.4.5 Circumferential Compression in Stiffeners, equations 4.14, 4.15, 4.16
-
4.4.7 Minimum Structural Plate Thickness
-
5.2.2 Wind Responses, equations 5.3, 5.4 and (1),(2) and (3), (b) equations 5.5, 5.6 and 5.7
Design Modification
If any of the modifications is set to yes, the software corrects the item should it fail in the analysis. For example, if Select Wall Thickness for Internal Pressure was set to Yes, PV Elite automatically increases the thickness of a component should it not be thick enough.