API 650 Appendix P still with errors?

[garfio]

I've been checking the last versions of API 650 Appendix P because I found some discrepancies with the stress factors used to calculate nozzle stresses on the alternative method (P.3). Even in Addenda 1 of the 11th edition (2008), I found that:

a) The labels for lines in Figures P-8A to P-8F are flipped with respect to what the formulas on the same figure show.

b) The formulas in those figures do match the formulas shown in table P.2. The upper limit (u) in table P.2 is also consistent with the labels being flipped.

c) Sample Problem 2 calculates stress factors consistent with the formulas, with exception of the first two values (stress factors for FR). Of these two, one matches the value in figure P-8F (if the flipped label is used), and the other does not match anything.

d) Values for "u" in the X axis of figure P-8H seem to be in the wrong location.

Does anybody have any information that help me confirm or correct my findings? I need to do some calculations and am surprised to see how issues in Appendix P have been on for years, and after erratas and appendixes, there are still problems.

 

[IFRs]

Please send an inquiry to API with your specific issues, with examples. The committee will address your concerns.

 

[jte]

As IFRs suggested, submitting an inquiry to API would be good.

Part of the original source material is available for $15 at

http://store.asme.org/product.asp?c...Papers&category_name=&product_id=PVP2002-1279

Might be worth the few dollars to compare how the data in the paper got transcribed into the standard.

Let us know how it works out!

jt

 

[JohnGP]

garfio,

I generally agree with what you have noted. I think I found that the first 4 figures P-8A to P-8D were incorrectly marked with respect to the formulas, while in P-8E the line marked t/t_n=10 should be t/t_n=5. Apart from the differences you noted for Sample Problem 2, I also differed in the calculation of factors for the other two Sample Problems.

What's a bit weird (I just checked Add4 of the 10th Ed) is that the first factor in Table P-5 was corrected to 0.968 in 10th Ed-Add4, but in 11th Ed (including Add1), the former 0.884 appears in the table, but the calculation below it uses the correct value of 0.968(?).

Some earlier discussion happened a few years ago -

http://www.eng-tips.com/viewthread.cfm?qid=148636

, and I'm a bit embarrassed not to have taken the whole lot a bit further with the Committee. I did send an email six months ago about the ongoing chart problems mentioned above and received a response that the Committee would be advised, but maybe that was too close to the publication date for Addendum1.

Pressures of work, blah, blah, and all that have distracted me from having a detailed look through Appendix P and highlighting the problems that remain. It needs doing though.

John