Shell/Tube - Internal Pressure

Owned by Former user (Deleted)
Last updated: Oct 06, 2016 by Mike Hartnett

(Includes Jacket and Heat Exchanger Components)

Use Diameter: This option is only available for some components. The user may choose to input dimensions as the inside dimensions or the outside dimensions where this option is available. For some components (such as shell), the use of outside dimensions for internal pressure calculations may result in a slightly higher required thickness.

Solve For: This option is only available for some components. The user may choose to solve for thickness or for pressure where this option is available. The “Solve for Thickness” option is more favorable when doing nozzle calculations for nozzles that use the current component as host.

Pressure: The internal design pressure (pressure on the concave side). This value is gauge pressure. When “Solve for Thickness” is selected, this value is an input and should not include static head. When “Solve for Pressure” is selected, this value is a result. In the latter case, it represents the total internal pressure (design pressure plus head) that the component can handle and meet code in the absence of any other loadings.

Static Head: The internal pressure (pressure on the concave side) resulting from the static head of the fluid. The user must determine this value and input it accordingly. It will be added to the Pressure input and the sum will be used in the internal pressure calculations for the component. This field will not be present when “Solve for Pressure” is selected.

Temperature: The maximum mean metal design temperature for the internal pressure case as defined in UG-20(a).

Length: The length of the shell component. If this component represents multiple shell courses, make sure that this length is the total length of the shell courses that are attached end to end.

Diameter: The component diameter in the new condition. The selection in the “Use Diameter” area determines whether this is the inside or outside diameter of the component. In the context of curved heads, this value is specifically the skirt diameter. For circular flat heads, this is the diameter as defined in per the configuration in UG-34.

Inside CA: Corrosion allowance on the inside of the component (concave side).

Circ. Joint Efficiency: The joint efficiency of the circumferential joints (girth seams) in the shell component. This is determined from Table UW-12 for welded joints. This may also represent circumferential ligament efficiency per UG-53. When both ligaments and welded joints exist, the lowest efficiency is used. See Appendix L for further help in determining the efficiency.

Long. Joint Efficiency: The joint efficiency of the longitudinal joints (long seams) in the shell component. This is determined from Table UW-12 for welded joints. This may also represent longitudinal ligament efficiency per UG-53. When both ligaments and welded joints exist, the lowest efficiency is used. See Appendix L for further help in determining the efficiency.

calculator button
Joint Efficiency Calculator: Click the button next to the field to calculate. If the inputs return a logical value per UW-12, the joint efficiency will be displayed in the calculator. To apply this value to the field, select Ok. The value in the field can be manually entered even after using this calculator.

Quantity: The number of tubes that this component represents. This field is only available for the tube component.

External CA: Corrosion allowance on the outside of the component (convex side). This field is available for internal heads and for the inner components of a jacketed vessel.

The following fields are not used by this software; they are listed here for the convenience of filling out the data forms in DesignDocs and FormPro.


Radiography (Circ.): This field represents the degree of radiography performed on the circumferential joints (girth seams). See UW-11 for more information.

Joint type (Circ.): This field represents the joint type for the circumferential joints (girth seams) in the shell. See Table UW-12 for more information.

Radiography (Long.): This field represents the degree of radiography performed on the longitudinal joints (long seams). See UW-11 for more information.

Joint Type (Long.): This field represents the joint type for the circumferential joints (girth seams) in the shell. See Table UW-12 for more information.

Heat Treatment Temperature: Review Subsection C of Section VIII, Division 1 to better determine the required heat treatment temperature for your component and material.

Heat Treatment Time: Review Subsection C of Section VIII, Division 1 to better determine the required heat treatment time for your component and material.


Nominal t: This value is in the new condition. For the component to pass, this value must be at least the sum of the thickness necessary for pressure and temperature, corrosion allowances, and forming allowances or under-tolerances. If the thickness necessary for pressure and temperature is less than the thickness required by UG-16, the nominal thickness must be at least the sum of the UG-16 thickness and the tolerances, etc. In some cases, under-tolerance is not considered (e.g., for nozzle reinforcement, the under-tolerance of the nozzle neck is ignored). When “Solve for Thickness” is selected, the software will determine the smallest standard size that passes. The user is able to manually edit this value.