ASME B31.4 - 2009 Combining of stresses

Dear Members,

The following are the query related to ASME B31.4 stresses and loads,

1. Is Caesar-II checking the "combining of stresses" as per B31.4 - 2009, sec. 402.7 for restrained pipe? If not how to prepare the load case?
2. What is the allowable stress for "combining of stresses" requirement?
3. Is caesar-II calculating the pipe-to-soil interaction as per guidelines in ASCE - American Lifelines Alliance (ALA) "Guidelines for the design of buried pipelines"?
4. Is caesar-II have any option to calculate the additonal loads and stresses as specified in ALA "Guidelines for the design of buried pipelines" such as Through wall bending, ring buckling, buoyancy, etc.
5. Is there is any possibility in future to add additonal calculation related to pipeline of aboveground and underground such as API RP 1102 - Stresses from road and railway traffic loads, elastic bending calc, upheaval buckling calc, water table calc etc.
6. One of client recommends that the Caesar-II calculated virtual anchor length is not precise and conservative compared to the virtual anchor length calculated by Autopipe. So client inform us to calculate the stiffness manually as procedure and formula provided in Autopipe user guide manual and input in Caesar-II soil model to carry out the analysis. So please confirm on what basis Caesar-II calculate the soil springs for buried pipeline.

Thankyou.

1) No, there are mistakes in this edition of the Code that have to be resolved before it can be incorporated into the software.

2) This is an item to be resolved.

3) That is an option.

4) No.

5) Maybe, as time permits.

6) The CAESAR II soil stiffnesses are computed according to the papers published by L. C. Peng. If Autopipe is using a different method, that's why the results are different.

About point 6, you may consult Mr. Peng's articles (and understand the limits of his approach) at:
http://www.pipestress.com/Pages/PEpapers.html

In my opinion, ALA method/data should be counted as accurate enough.

Best regards.

Hi Richard,

1. So Caesar-II stress analysis for ASME B31.4 code is as per 2006 editon only till date.

3. As per your reply for query # 3, is any option in Caesar-II available to calculate the soil properties as per ALA method. If so where it is and in which version of Caesar-II..