In reviewing the analysis results for a model I have been working on, I found an inconsistency which I would appreciate assistance in resolving. The allowable expansion stress decreased when I changed the material from A333-6 to 5LX-X60. Trying to understand why this occurred, I found that the Syt values for all of the 5LX-X60 and 5LX-X65 in the model were automatically returning as zero. Looking at the "B315-12.LIB Code Materials" in the help, I saw the following notes: 1. ASME B31.4 does not use temperature-dependent allowable stress values (all allowable stresses are calculated from the yield stress). 2. The following code materials do not have temperature-dependent yield strengths: 5L-A25, 5L-A, 5L-B, A524-H, 5LU-U80, 5LU-U100, 5LX-X42, 5LX-X46, 5LX-X52, 5LX-X56, 5LX-X65, 5LX-X70, 5LS-A, 5LS-B, A139-A, 139-B. When these temperature-dependent yield strengths are not available, AutoPIPE uses the specified minimum yield strengths taken from ASME B31.4. These values may be unconservative and an alternate yield should be considered in the Yield field of the Operating Pressure & Temperature dialog. It appears that AutoPIPE is trying to use temperature-dependent yield strengths that are not available, however instead of providing the specified minimum yield strength, it is using zero. Is this an issue with the model or an issue within AutoPIPE? I can continue working by manually entering the Syt values, however I felt I should mention the issue after encountering it. I am currently using version 09.06.01.10.
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