Last time this article was updated: 08/01/2019
Spreadsheet version used in this article: 1.00 – 16/01/2019

1. Introduction

This is the documentation for the Saddle Support Design Spreadsheet. Here you will find all information regarding it: how to use, the limitations, fields description, possible troubleshoots, next improvements and so on. So, read it carefully before using it and if you find some problem, come here first to see if there’s a fix or an explanation before contacting me. If you want to know all theory behind this spreadsheet, see this article and if you want to check its validation, click here.

For now, this spreadsheet will only cover the ASME BPVC Section VIII Division 2, which don’t address the support design (base plate, web, etc), for that I’ll use the methods described in the Pressure Vessel Design Manual from Dennis R. Moss and Michael M. Basic [1],  in a future version.

2. Fields

The fields in the spreadsheet are separated in two groups: unlocked or input and locked or output, which are further separated into more specific groups, as shown below.

Unlocked/Input:

  • Operation Condition
    Information regarding the temperature and pressure used, which are classified in two types: operating and design. It’s the same meaning of the operating and design variables used in the rest of the ASME Code: operating means the real value and design, as the name sugests, is the value used to design the vessel. The design value must always be higher than the operating.
  • Pressure Vessel
    Information about the vessel itself, the basic dimensions, the materials, type of head, if it have reinforcing plate and stiffening, joint efficiency of the welds, and the total amount of force exerced in the saddle supports, which should be calculated previously by the engineer.
  • Saddle Support
    Basic dimensions of the saddle support and the type of connection with the cylindrical shell (welded or resting). There’s not much fields in this group because this spreadsheet only cover the ASME BPVC Section VIII Division 2 and it don’t address the design of the saddle (web, base plate, etc), but the next version will use some of the Pressure Vessel Design Manual methods/calculations to fill this gap.
  • Stiffening Ring
    If you have selected “Yes” in the “SRing” dropdown list (Pressure Vessel group), then the stiffening ring properties will be shown. Note that this group have locked cells (Asra, c1, c2 and I) which correspond to geometry properties and are automaticaly calculated. In this group you have to choose the shape of the ring (C, L, W or bar), if it’s mounted inside or outside the shell and the distance of the two rings, if there’s two of them.
  • Shape Properties
  • Geometry Property

Lock/Output:

  • Moments and Shsear
  • Stress Coefficients
  • Moembrane / Compressive / Longitudinal Stresses
  • Shear Stress
  • Circumferential Stresses
  • Saddle Reaction

3. Troubleshooting

  1. The spredsheet freezes for a while  after I change the value of a cell or a dropdown.
    It happens because the spreadsheet relies heavily on VBA code, which hide row, cells, show the images and so on.
  2. When I try to change from a configuration with reinforcing plate and no stiffening ring to a configuration with stiffening ring, through the “STRing” dropdown, no image appears.
    It happen because the VBA can’t identify the variable “RPlate” as “No” before runing the rest of the code and, as there’s no configuration for stiffening ring with reinforcing plate, there’s no image to show. Just change the value of a cell or a dropdown to update the spreadsheet and the image will appear.
  3. Variable Pd in the Operation Conditions is not used, instead the spreadsheet use the “P” variable.
    It’ll be fixed in the next version, as the spreadsheet should use “Pd” instead of “P”. For now, just consider your design pressure as the operating pressure.
  4. There’s two “h” variable: one that correspond to the distance between saddle supports and other that correspond to the distance between stiffening rings.
    The “h” dimension shown in the spreadsheet figure which correspond to the distance between the two saddle supports will be removed in the next version. The correct “h” variable correspond to the distance between two stiffening rings.

References   [ + ]

1.Moss, Dennis R., and Michael M. Basic. Pressure Vessel Design Manual. 4th ed., Butterworth-Heinemann, 2013