Last Updated: 2023.12

(Fixed, Floating)

Calculate Welds Using: Select the desired weld design equations. To consider the expanded tube length in lending strength at the joint, select UW-20.4.

Joint Type: Only applicable to UW-20.4 (formerly Appendix A) joints; see UW-20.4 (formerly. Appendix A) for more information.

Weld Configuration: Select the weld configuration. For UW-20.4 (formerly Appendix A) calculations, the options in this field are dependent upon the type of joint selected. UW-20 configurations were expanded in 2021 to add e partial strength, f full strength and f partial strength; the software allows these three new options for all code years.

UW-20.4 (formerly Appendix A) Configurations have changed their denotation over the years. In 2021, (f) and (g) swapped and the option to pick (b-1) was removed. The software shows the 2023 configurations regardless of the year selected for the vessel. The table below shows the 2023 equivalents to the older years.

Appendix A Configuration Equivalents

2023	2021	2019 - 2015	2013 - 2010
Fig. UW-20.2(a)	Fig. A-2(a)	Fig. A-2(a)	Fig. A-2.1
Fig. UW-20.2(b)	Fig. A-2(b)	Fig. A-2(b)	Fig. A-2.2
Fig. UW-20.2(c)	Fig. A-2(c)	Fig. A-2(c)	Fig. A-2.3
Fig. UW-20.2(d)	Fig. A-2(d)	Fig. A-2(d)	Fig. A-2.4
Fig. UW-20.2(e)	Fig. A-2(e)	Fig. A-2(e)	Fig. A-2.5
Fig. UW-20.2(f)	Fig. A-2(f)	Fig. A-2(g)	Fig. A-2.7
Fig. UW-20.2(g)	Fig. A-2(g)	Fig. A-2(f)	Fig. A-2.6
Fig. UW-20.2(h)	Fig. A-2(h)	Fig. A-2(h)	Fig. A-2.7
Fig. UW-20.2(i)	Fig. A-2(i)	Fig. A-2(i)	Fig. A-2.8

Weld Type: Select whether the weld is Full Strength, Partial Strength, or Seal. This only applies to calculations per UW-20.2.

Fillet Leg: The length of the fillet weld leg. This only applies to calculations per UW-20.2.

Design Strength: Applies to UW-20.2 partial strength welds. This value will be compared with the axial tube strength (Ft) and the lower value will be used in the calculations.

Groove Leg: The length of the groove weld leg. This only applies to calculations per UW-20.2.

fr Basis: The options are “Test”, “No Test”, and “Custom”. If “Test” or “No Test” is selected, the design calculations will use the values provided in Table UW-20.1 (formerly Table A-2) for fr. A value of zero will be used if the Type Joint is b-1 and the “fr Basis” is “No Test”. If the basis selection is “Custom”, the value of fr used in the design calculations will be the user input value “fr Custom”. New designs will have this set to “No Test” by default. Designs created before 2020.0 and patched to the current release, will have this field set to “Custom”. This only applies to calculations per UW-20.4 (formerly Appendix A).

fr Custom: This is a user editable value for fr, for cases where the user does not wish to use the Test or No Test values from UW-20.1 (formerly Table A-2) in UW-20. This value must be 0 or greater and anything over 1 will be reduced to 1 in the design calculations. The value of fr in the design calculations will be set to “fr Custom” if the “fr Basis” selection is “Custom”; otherwise this field is ignored in the calculations. New designs will have this set to 0 by default. Designs created before 2020.0 and patched to the current release, will have this field set to the “Joint Efficiency Factor (fr)” value from the older version. This only applies to calculations per UW-20.4 (formerly Appendix A)..

fr(b): This value was introduced in the 2019 version of Appendix A and represents the efficiency of the weld only at the tube to tubesheet joint. Patched and new designs will have this set to 0. This value must be 0 or greater and anything over 1 will be reduced to 1 in the design calculations. This value is only used in design calculations for joint types of f, g or h for Code Years 2019 and later; otherwise the value is ignored. This only applies to calculations per UW-20.4 (formerly Appendix A).

Use Calculated Po and PT Values: New designs will have this checked by default. Designs created before 2020.0 and patched to the current release, will have this unchecked. If this is checked, the software will use the equations for Po and PT introduced in the 2019 version of Appendix A, otherwise it will use the custom input values “Po Custom” and “PT Custom”. Po and PT are only used for joint types i, j, k for all code years and f, g and h for the 2019 and later code years. This only applies to calculations per UW-20.4 (formerly Appendix A).

Po Custom: This is the user editable value for Po, for cases where the user does not wish to use the Po equation introduced in the 2019 version of Appendix A. Po is the interface pressure between the tube and the tubesheet that remains after expanding the tube into the tubesheet. Po is only used for joint types i, j, k for all code years and f, g and h for the 2019 and later code years. Po will only be set to this value in the design calculations in one of these cases when "Use Calculated Po and PT Values" is checked; otherwise this value is ignored. New designs will have this value set to 1. Designs created before 2020.0 and patched to the current release will have this value set to "Interface pressure after expanding (Po)" from the older version, unless both Po and PT are zero, then the patch will set it to 1. This only applies to calculations per UW-20.4 (formerly Appendix A).

PT Custom: This is the user editable value for PT, for cases where the user does not wish to use the PT equation introduced in the 2019 version of Appendix A. Po is the interface pressure between the tube and the tubesheet that remains after expanding the tube into the tubesheet. PT is only used joint types i, j, k for all code years and f, g and h for the 2019 and later code years. PT will only be set to this value in the design calculations in one of these cases when "Use Calculated Po and PT Values" is checked; otherwise this value is ignored. New designs will have this value set to -1. Designs created before 2020.0 and patched to the current release will have this value set to "Interface pressure due to thermal growth (Pt)" from the older version, unless both Po and PT are zero, then the patch will set it to -1. This only applies to calculations per UW-20.4 (formerly Appendix A).

Related articles

Page:

Tubesheet - Tube
Page:

Tubesheet - Tube to TS Joints
Page:

Tubesheet - Conditions
Page:

Tubesheet - Figures
Page:

Tubesheet - Why are some of my results showing as NC