Home Tab > Components > Add New Thick Joint 
Applies to fixed tubesheet exchangers, which require flexible elements to reduce shell and tube longitudinal stresses, tubesheet thickness, or tube-to-tubesheet joint loads. Light gauge bellows type expansion joints within the scope of the Standards of the Expansion Joint Manufacturers Association (EJMA) are not included within the purview of this paragraph. The analysis contained within these paragraphs is based upon the equivalent geometry used in Expansion Joints for Heat Exchangers by S. Kopp and M.F. Sayre; however, the formulas have been derived based upon the use of plate and shell theory. Flanged-only and flanged-and-flued types of expansion joints can be analyzed with this method. (TEMA 8th Edition, Paragraph RCB-8, page 61).
The formulas contained in the module are applicable based on the following assumptions:
-
Applied loadings are axial.
-
Torsional loads are negligible.
-
Flexible elements are sufficiently thick to avoid instability.
-
Flexible elements are axisymmetric.
-
All dimensions are in inches and all forces are in force-pounds.
Per TEMA Eighth Edition, Paragraph RCB-8.1, page 61, other systems of units may be
used for input and output since the program converts these to inches and pounds for
its internal calculations.
The sequence of calculations used by the software is:
-
Select a geometry for the flexible element per RCB-8.21 (user-defined).
-
Determine the effective geometry constants per RCB-8.22.
-
Calculate the flexibility factors per RCB-8.3.
-
Calculate the flexible element geometry factors per RCB-8.4.
-
Calculate the overall shell spring rate with all contributions from flexible shell elements per RCB-8.5.
-
Calculate FAX for each condition as shown in Table RCB-8.6. This requires that you run the CodeCalc Tubesheet module to determine the differential expansion and shell side and tube side equivalent pressures.
-
Calculate the flexible element stresses per RCB-8.7
-
Compare the flexible element stresses to the appropriate allowable stresses per the Code for the load conditions as noted in step 6.
-
Modify the geometry and rerun the program if necessary.
More than one analysis may be needed to evaluate the hydrotest and uncorroded conditions.
Thick expansion joints can also be designed in the Tubesheet module. This integration allows CodeCalc to automatically transfer the needed information between the tubesheet and the expansion joint calculation.
Figure Thick Joint Module Geometry shows the geometry for the Thick Joints module. (TEMA Figure RCB-8.21 and RCB-8.22). Both the input geometry and the equivalent geometry used for the analysis are shown. The discussion of input data below uses the nomenclature shown on this figure.
The stresses computed from the TEMA standard are compared to their respective allowables, as per APP-5 in ASME code Sec. VIII Div. 1. The cycle life is also computed to address the fatigue consideration.
