Boiler & Pressure Vessel Code, Rules for Construction of Nuclear Power Plant Components Division 1, Subsection ND, Class 3 Components Applies To Product(s): AutoPIPE, Version(s): 2004, XM, & V8i Environment: N/A Area: piping code Subarea: Original Author: Bentley Technical Support Group Comments, Questions, and Answers on ASME ND Piping code in AutoPIPE #1. Question: For a system for which level C service conditions are specified in the Design Specification, ASME Section III Subsection ND requires "the conditions of eqs. ND-3653.1 (a)(9a) and ND-3653.1(b)(9b) shall be met using Service Level C coincident pressure P and moment (MA + MB), which result in the maximum calculated stress. AutoPIPE appears to use the "Peak Pressure" when performing this calculation. If the Service Level C coincident pressure P differs from the Peak Pressure (Level A and B), how can the Level C pressure be specified for this calculation? Answer : AutoPIPE conservatively used peak pressure as it isn't able to identify the load case to get the coincident pressure from. Reprocess the results manually to check the affect of this. #2. Question: How to find out what SIF does AutoPIPE use for stress calculations in each point, for example in tees using ASME ND 1992+1993 addenda? Answer : See AutoPIPE output report Stress Indices. #3. Question: I have a question regarding ND equation 10 code stress combination for thermal case . Autopipe combines zero moment case. I could not get more detail or explanation of zero moment case from Autopipe work book. Can you please explain what is zero moment case and which code clause states this requirement to be included in the stress calculation? Answer: ASME III Class 1 requires transient temperature distribution analysis across the pipe wall thickness for computing linear and non-linear thermal stresses. The temperature distribution range T(y) may be thought of as being composed of three parts: 1. A constant value, which is the average value through the pipe wall thickness. For gross discontinuity locations the T value is determined on each side of the discontinuity and is the Ta and Tb values used in ASME NB Equations 10 and 11. 2. A linear portion, with zero average value; determined by evaluating the moment generated inside the pipe wall thickness and solving for delta T1 3. A non-linear portion with a zero average value and a zero first moment with respect to the mid thickness. For Equation 10 in the Stress Summary dialog, the zero option indicates the inclusion of a zero moment option corresponding to zero pressure, zero moment and room temperature. Also please see the following code section: NB-3653.1 Satisfaction of Primary Plus Secondary Stress Intensity Range See Also Bentley AutoPIPE External Links Bentley Technical Support KnowledgeBase Bentley LEARN Server Comments or Corrections? Bentley's Technical Support Group requests that you please submit any comments you have on this Wiki article to the "Comments" area below. THANK YOU!
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