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Becht Engineering Blog

In this section of the site contributing authors submit interesting articles relating to the various services, industries and research & development efforts of Becht Engineering.

Becht Engineering staff are experts in piping, and include former chairman of various ASME piping committees, including ASME B31.3. Becht Engineering performs detailed design for complex piping systems including very high temperature and pressure systems such as piping for FCC flue gas expanders and high pressure LDPE systems, as well as design, analysis, troubleshooting and fitness for service evaluation of piping.

Capacity Reduction of a Compression Member with an Initial Deformation

piping_support_3D
A recent review of equipment installed in a power plant found a piping strut that was visibly bent. Would the bend in the strut reduce its load bearing capacity as a compression member? The answer is YES!  The load bearing capacity of a bent strut against buckling is reduced. The reduction in buckling capacity is a function of the strut’s section properties and its initial deformation. We will see here how this can be quantified analytically (closed-form solution) and numerically (FEA solution). The equation for the maximum axial load capacity of a column, before it buckles, was first formulated by Leonhard Euler in 1757. F cr  = (π 2  E I)/(K L) 2 Where E = Young’s modulus of column material; I = cross-sectional moment of inertia of the column; L = unbraced length of column; and K is a factor that depends on the degree of fixity in the...
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Evaluation of Corroded Pipe in Accordance with ASME B&PV Code Section XI - A Comparison of the Three Code Cases

Evaluation of Corroded Pipe in Accordance with ASME B&PV Code Section XI -
A Comparison of the Three Code Cases
The evaluation of wall thinning corrosion in steel pipes is addressed in three ASME XI code cases: N-513, N-597, and N-806. I have no ambition here other than to summarize in a table the differences between these three code cases. A brief commentary follows the table. The brief commentary... Line A – While these are Section XI Code Cases applicable to ASME III Class 2 and 3, technically, nothing would prevent from applying these Code Cases for B31.1 piping. Line B – There is no technical basis for limiting N-513 to moderate energy lines, i.e. pressure at or below 275 psi and (“or”, depending on the plant vintage) temperature at or below 200oF, other than the understandable reluctance to operate with hot water flashing to steam through a pinhole leak. Line D – It can be confusing that N-513 includes fracture mechanics consideration because it attempts to address cracks (so-called...
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ASME III Appendix F – A Valuable Guide to the Operability Assessment of Piping Systems

ASME III Appendix F – A Valuable Guide to the Operability Assessment of Piping Systems
The NRC Inspection Manual Chapter 0326 refers to ASME III Appendix F as an acceptable method for the evaluation of “a degradation or nonconformance associated with piping or pipe supports …”. Appendix F provides five alternative methods for the qualification of pressure equipment, piping, and their supports. They are: (1) elastic analysis, (2) plastic analysis, (3) limit collapse analysis, (4) plastic collapse analysis, and (5) plastic instability analysis. Each of the five methods provides a different way of approaching the evaluation, with criteria that are specifically matched to the method. In this manner Appendix F reduces the conservatism inherent to the design analysis methods for normal operating conditions. The Level D Service Limits and design rules contained in Appendix F are intended (F‑1200) to prevent the rupture of the pressure‐retaining boundary, but are not intended to assure operability of components during or following the specified event. Following is a brief description of each of the five Appendix...
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Repair of Pressure Equipment and Piping in Nuclear Power Plants- Navigating ASME XI Repairs with PCC-2 as a Roadmap

Repair of Pressure Equipment and Piping in Nuclear Power Plants-
Navigating ASME XI Repairs with PCC-2 as a Roadmap
Download/View as PDF Summary - This article assists engineers in selecting ASME XI options for the repair of ASME III nuclear components. In summary, the repair options in ASME XI are dispersed throughout Section XI and Code Cases, while, in contrast, the ASME PCC-2 repair standard (for non-safety related components) lists repair options in a well-structured manner. So, we are going to use the structure of ASME PCC-2 as a road map to cross-correlate the equivalent ASME XI repair, where it exists. Therefore, the Table can be used as a checklist to remind engineers of the many repair options. On one hand …. ASME XI : The repair of safety-related Class 1, 2, and 3 nuclear components is addressed in ASME Boiler & Pressure Vessel Code Section XI and in a series of ASME XI Code Cases. The use of ASME XI and its Code Cases to select a repair...
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