UG-29 Clarifications

[jproj]

I am trying to work through UG-29(a) and have a couple of questions.

1) Assuming the vessel has multiple stiffening rings, are I and I' the moments of inertia for a single stiffening ring, or the sum of all stiffening ring inertias?

2) Similar to the above question, is As the total cross sectional area (# rings * ring x-sectional area), or just the cross sectional area of one ring?

3) When calculating Is', does As include the contributing piece of the vessel shell (1.1*(Do*ts)^0.5), or is As only the stiffening ring area?

4) I noticed that the first Factor A and B values listed for each temperature in Table CS-2 are off by a factor of 10 compared to left most values shown on each temperature line on Fig. CS-2.

Example:
Fig. CS-2 (500ºF line)
Factor B = 2,500 (0.250e+4)
Factor A = 0.000194 (0.194e-3).

Table CS-2 (500ºF)
Factor B = 250 (0.250e+3)
Factor A = 0.0000194 (0.194e-4).

My question is, are the lines on the figure supposed to extend to the values shown in the table (thereby extending the area to the left where the figure applies), or are the first values in the Table typos and once Factor A is less than 0.194e-3, the P = 2AE/3(Do/t) formula applies?

Let me know if I need to clarify anything.

Thanks!

jproj

 

[SnTMan]

jproj, 1) & 2) are for a single ring.
3) is the combined section, see the definitions
4) I don't recall noticing this before, and don't know how to explain it. There appear to be typos in the tabulated values...

Regards,

Mike

 

[doct9960]

jproj,

4) I noticed that the first Factor A and B values listed for each temperature in Table CS-2 are off by a factor of 10 compared to left most values shown on each temperature line on Fig. CS-2.

Example:
Fig. CS-2 (500ºF line)
Factor B = 2,500 (0.250e+4)
Factor A = 0.000194 (0.194e-3).

Table CS-2 (500ºF)
Factor B = 250 (0.250e+3)
Factor A = 0.0000194 (0.194e-4).

My question is, are the lines on the figure supposed to extend to the values shown in the table (thereby extending the area to the left where the figure applies), or are the first values in the Table typos and once Factor A is less than 0.194e-3, the P = 2AE/3(Do/t) formula applies?

Read Step 2a in UG-29(a). If you are going to use the Table, you need to INTERPOLATE between adjacent tabular values.

So for 500°F & B = 2500 in Table CS-2, if you interpolate between B = 0.250 +03 and B = 0.900 +04, you should get A = 0.000188

 

[jproj]

SnTMan,

After a few more calculations, I have concluded that the tabular values are not typos, but are approximately equal to the result obtained from the formula B = 2A/E (as described in Setp 5 when B is below the values given on the figure).

Thanks for the clarifications.

 

[SnTMan]

jproj, doct9960, I had worked fairly regularly with those tables and figures a number of years in the past (by hand), but have gotten rusty with them. I am going to have to get back to them when I have time and satisfy myself.

Regards,

Mike