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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.

Ken Stoops has over 11 years of experience in mechanical engineering design and analysis. He also has over 4 years experience in nuclear Quality Assurance (QA), and currently serves as Quality Assurance Manager for Becht Nuclear Services. In his role as an engineer, his fields of expertise include seismic analysis of vessels, piping, lifting beams, air filter housings, and other structures. Mr. Stoops specializes in advanced finite element modeling and simulation of complex problemsusing ANSYS finite element analysis (FEA) computer program.

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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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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Loads on Buried Pipe: A 100-Year Old Empirical Formula Still Holds Water

Loads on Buried Pipe:  A 100-Year Old Empirical Formula Still Holds Water
The evaluation of the effects of surcharge loads on buried pipes can be addressed using the Iowa formula. This formula, over 100 years old, matches the results of state-of-the-art finite element analysis with pipe-soil interaction. In 1913, Iowa State University professors Marston and Anderson published the results of their experimental work on the resistance of concrete pipes to large surcharge loads ( Marston, A., and Anderson, A.O., The Theory of Loads on Pipes in Ditches, and Tests of Cement Clay Drain Tile and Sewer Pipe, Bulletin 31, Iowa Engineering Experiment Station, Iowa State University, Ames, Iowa, 1913). Their experimental work was triggered by the failures that were occurring in the agricultural fields as early tractors were driving over shallow-buried pipes. They developed a simple formula for the ovality of the pipe under surface loads, which has since been known as the Iowa formula.          In 1941 Spangler...
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Working on the Road - Using the Cloud

I was recently preparing for a cross-country trip and I had to decide what to take. Normally it is necessary to bring several large binders of subject and reference material, but in between airline baggage restrictions and the need to travel light I didn't want to take a lot of stuff. Fortunately, modern technology is on my side. I was able to send my documents on ahead of me electronically to print on-site courtesy copies for the client, and also to place a copy on my laptop and cell phone for instant access even when offline. While on-site the client requested documents that I did not have already with me. No problem, I was connected to Becht's cloud data service that gives me access to all my files anywhere in the world. In the (hypothetical) event that I planned poorly and left a file on my office pc back home,...
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