First Release: 2021.X
General Info
Description: This defaults to ‘Half Pipe Jacket’ and is used in the Half Pipe Browser and in the report selection.
System of Units: This is currently limited to Customary.
Dimensions
Host Inside Diameter: This input will be used directly in the calculation; so adjust this as necessary for corrosion, etc. If the head or shell has a diameter that varies, pick a conservative diameter to use. Larger diameters tend to be more conservative resulting in lower allowable pressure in the jacket. The default value is 60”.
Host Nominal Thickness: This input will be used directly in the calculation; so adjust this as necessary for corrosion, etc. The default value is 0.25”.
NPS: The options are 2, 3 and 4 to be compliant with the scope and method basis. The default value is 2.
Nominal Pipe Thickness: This is the jacket thickness. This input will be used directly in the calculation; so adjust this as necessary for corrosion, etc. The default value is 0.2”.
Pipe Radius: This is the jacket radius. This input will be used directly in the calculation; so adjust this as necessary for corrosion, etc. The default value is 1”.
Loading Conditions
Pressure: This input will be used directly in the calculation; so adjust this as necessary for static head, etc.
Sj: This is the allowable stress of the jacket for the condition under consideration. The default value is 20000 psi.
S: This is the allowable stress of the vessel for the condition under consideration. The default value is 20000 psi.
S': This is the actual longitudinal stress in the vessel for internal pressure and axial loads for the condition under consideration. If the longitudinal stress is negative, input zero. The default value is 20000 psi.
Scope
This method supports half-pipe jackets attached to a shell or head with a thickness between 3/16” (19 mm) and 2” (50 mm) inclusive. The half-pipe is limited to NPS 2, NPS 3 and NPS 4. There must be positive pressure in both the vessel and the jacket. The method has some consideration for external loads on the shell or head; but not on the jacket.
Method Basis
The calculations are based on ASME Section VIII, Division 1 Appendix EE and Section VIII, Division 2 4.11.6. These methods are essentially identical. The only difference is that Division 1 provides figures that a user may read to obtain the K value and Division 2 instead provides curve fit equation for these curves to determine the K value. This method uses the curve fit from Division 2 in all cases as it provides better standardization and is therefore easier to explain and justify to third party reviewers.