ASME B31.3 Appendices P and S: Compensating for Shortcomings

Author(s):  
Don R. Edwards

The 2004 edition of ASME B31.3 Process Piping Code [1] introduced both Appendix P and Appendix S Example 1; Examples 2 and 3 were included in the 2006 edition. Appendix P is to illustrate a nearly computer stress analysis basis by defining alternative rules for displacement stress range evaluation, and Appendix S contains examples describing how to satisfy the requirements of B31.3 when performing computer based stress analysis. As is possible with any extensive addition to any code, these first offerings contained shortcomings either explicitly or by lack of clarity. This paper discusses some of these issues, provides workarounds when using today’s commercially available piping stress analysis software, and proposes revisions to both Appendices for the 2010 edition of the B31.3 Process Piping Code.

Author(s):  
Don R. Edwards

The American Standards Association (ASA) B31.3-1959 Petroleum Refinery Piping Code [1] grew out of an ASA document that addressed all manner of fluid conveying piping systems. ASA B31.3 was created long before widespread engineering use of computer “mainframes” or even before the inception of piping stress analysis software. Also as B31.3 continued to pass thru standards organizations from ASA, ANSI, to ASME, the B31.3 Process Piping Code [2] (hereafter referred to as the “Code”) has remained ambiguous over the past few decades in several areas. The displacement stress range, SE, has always been explicitly defined by both verbiage and equation. Yet, the sustained condition(s) stress, SL, is mentioned not with an explicit equation but with a statement that the sustained stress shall be limited by the allowable stress at the corresponding operating temperature, Sh. Also one might infer from the vague verbiage in the Code that there is only one sustained condition; this would also be an incorrect inference. Also, assumptions would then have to be made as to which supports are allowed to be included in a sustained analysis based on whether the piping “lifts-off” any of the pipe supports during the corresponding operating condition. This paper describes the subtle yet possibly radical concepts that are included in the (recently approved for inclusion into) ASME B31.3-2006 Appendix S Example S2. This paper discusses: • when and in what manner the most severe set of operating temperature and pressure is to be used; • the concept of “sustained condition” and multiple “anticipated” sustained conditions; • determining the support scenario(s) for each anticipated sustained condition; • establishing the most severe sustained condition to evaluate and determine the stress due to sustained loads, SL; • utilizing an equation with sustained stress indices to evaluate SL; • establishing the least severe sustained condition and its effect in determining the largest displacement stress range, SE.


Author(s):  
Don R. Edwards

The American Standards Association (ASA) B31.3-1959 Petroleum Refinery Piping Code [1] grew out of an ASA document that addressed all manner of fluid conveying piping systems. ASA B31.3 was created long before widespread engineering use of computer “mainframes” or even before the inception of piping stress analysis software. From its inception until recent times, the B31.3 Process Piping Code [2] (hereafter referred to as the “Code”) has remained ambiguous in several areas. This paper describes some of these subtle concepts that are included in the Code 2006 Edition for Appendix S Example S3. This paper discusses: • the effect of moment reversal in determining the largest Displacement Stress Range, • the impact of the average axial stress caused by displacement strains on the Example S3 piping system and the augmenting of the Code Eq. (17) thereto, • a brief comparison of Example S3 results to that of the operating stress range evaluated in accordance with the 2006 Code Appendix P Alternative Requirements.


Author(s):  
Don R. Edwards

The American Standards Association (ASA) B31.3-1959 Petroleum Refinery Piping Code [1] grew out of an ASA document that addressed all manner of fluid conveying piping systems. ASA B31.3 was created long before widespread engineering use of computer “mainframes” or even before the inception of piping stress analysis software. Also as B31.3 continued to pass thru standards organizations from ASA, ANSI, to ASME, the B31.3 Process Piping Code [2] (hereafter referred to as the “Code”) has remained ambiguous over the past few decades in several areas. Ambiguities such as what temperatures and pressures are to be used during the pipe stress analysis process is addressed but apparently not clearly enough to make the point; the prevailing practice in the industry is to use the design pressure and temperature; but this is an incorrect inference from the Code. The misunderstandings as to the few, albeit very important, purposed uses for the design pressure and design temperature also appear to be prevalent in the industry. This paper describes some of these subtle yet possibly radical concepts that were included in the ASME B31.3-2004 Appendix S Example Sl. This paper discusses: • the design and analysis procedures in defining when the design conditions are actually to be used; • when and in what manner the most severe set of operating temperature and pressure is to be used; • and the debates that lasted over a decade to finally include into the Code such “seemingly simple” examples that address computer based stress analysis.


1990 ◽  
Vol 112 (3) ◽  
pp. 268-275 ◽  
Author(s):  
A. R. Heath ◽  
P. M. McNamara

The conflicting legislative and customer pressures on engine design, for example, combining low friction and a high level of refinement, require sophisticated tools if competitive designs are to be realized. This is particularly true of crankshafts, probably the most analyzed of all engine components. This paper describes the hierarchy of methods used for crankshaft stress analysis with case studies. A computer-based analysis system is described that combines FE and classical methods to allow optimized designs to be produced efficiently. At the lowest level simplified classical techniques are integrated into the CAD-based design process. These methods give the rapid feedback necessary to perform concept design iterations. Various levels of FE analysis are available to carry out more detailed analyses of the crankshaft. The FE studies may feed information to or take information from the classical methods. At the highest level a method for including the load sharing effects of the flexible crankshaft within a flexible block interconnected by nonlinear oil films is described. This method includes the FE modeling of the complete crankshaft and the consideration of its stress field throughout an engine cycle. Fatigue assessment is performed to calculate the distribution of fatigue safety factor on the surface of the crankshaft. This level of analysis can be used for failure investigation, or detailed design optimization and verification. The method is compatible with those used for vibration and oil film analysis.


2005 ◽  
Vol 128 (1) ◽  
pp. 84-88 ◽  
Author(s):  
Charles Becht ◽  
David W. Diehl

Alternative rules for performing flexibility analysis were added, as Appendix P, in ASME B31.3, the Process Piping Code, 2004 edition. These rules are considered to be more comprehensive than before; they were designed around computer flexibility analysis. To determine stress range, the difference in stress states, considering all loads, is computed. This paper describes the new rules, their intent, and provides several example piping stress analyses, comparing the results of an analysis using the Appendix P rules with that using the rules in the base Code.


Author(s):  
Don R. Edwards

For the first time in the history of the ASA [1], ANSI/ASME, ASME/ANSI, to the 2008 edition of ASME B31.3 Process Piping Code (hereafter referred to as “the Code”) [2], an equation for the Stress Due To Sustained Loads, SL, has been introduced into the Code. From its inception to the current edition, the Code has remained ambiguous in several areas. Even though the displacement stress range, SE, has been explicitly defined by both text and equation, the stress due to sustained loads, SL, is mentioned not with an explicit equation but with a statement that SL shall be limited by the allowable stress at the corresponding operating temperature, Sh. This paper describes the equation in detail and the background, the events, and the effort involved that led to the insertion of this equation into the Code.


Author(s):  
Bowen Li ◽  
Xinhang Li ◽  
Yubin Miao ◽  
Hao Yang

2021 ◽  
Vol 143 (5) ◽  
Author(s):  
Nikola Jaćimović ◽  
Sondre Luca Helgesen

Abstract ASME B31.3, the leading process piping system design code, has included in its 2018 edition a new procedure for evaluation of high cycle fatigue in process piping systems. As stated in the Appendix W of ASME B31.3-2018, this new procedure is applicable to any load resulting in the stress range in excess of 20.7 MPa (3.0 ksi) and with the total number of cycles exceeding 100,000. However, this new procedure is based on the stress range calculation typical to ASME B31 codes which underestimates the realistic expansion stress range by a factor of ∼2. While the allowable stress range used typically for fatigue evaluation of piping systems is adjusted to take into consideration this fact, the new fatigue design curves seem not to take it into account. Moreover, the applicability of the new design procedure (i.e., welded joint fatigue design curves) to the components which tend to fail away from the bends is questionable. Two examples are presented at the end of the paper in order to substantiate the indicated inconsistencies in the verification philosophy.


2014 ◽  
Vol 556-562 ◽  
pp. 4198-4201 ◽  
Author(s):  
Hong Jun Li ◽  
Long Yan ◽  
Jiu Jiang Yan ◽  
Wei Chen ◽  
Yan Li

In the existing squeezing machine of tube, the squeezing quality of tube is universally unstable, this paper apply dispersed forcing way to the movable squeezing plate, and build a new model of squeezing of the tube, using the professional analysis software Inventor to carry out stress analysis for the movable squeezing plate, the results show, in dispersed forcing way, the structural of model of squeezing of the tube design to be rational, and the tube force even, therefore the high-quality tube product can be obtained with the new model of squeezing of the tube.


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