Computer pipe stress analysis

A discussion of the methods used for the calculation of piping flexibility and stress analysis are beyond the scope of this book. Manual calculation techniques, and the application of computers in piping stress analysis, are discussed in the handbook edited by Nayyar et al. (2000). 

Computers have taken the hand calculation work out of piping stress analysis. However, because of time and cost, the computer is not available for many simple two-anchor pipe loops. 

The most recent developments in computational stmctural analysis are almost all based on the direct stiffness matrix method. As a result, piping stress computer programs such as SIMPLEX, ADLPIPE, NUPIPE, PIPESD, and CAESAR, to name a few, use the stiffness method. 

For dilute phase conveying numerical simulations with a commercial computational fluid dynamics code were carried out. The analysis of particle wall impact conditions in a pipe bend showed that they take place under low wall impact angles of 5-35° which results in low normal (5-25 m/s) and high tangential (33-44 m/s) impact velocity components. These findings lead to the conclusion that not only normal stresses caused by the impacts are important in dilute phase conveying but that sliding friction stresses play an important role as well. 

PZ constitute Crack Layer (CL) [6-8] and the rates of the crack and PZ growth characterize the kinetics of CL evolution. It is controlled by thermodynamic forces associated with crack and PZ respectively [8]. In this p er, a numerical algorithm and analysis of SCG computer simulations for PE is proposed based on CL theory. In addition, the lifetime of pipe is evaluated for various stress level, and the crack origin (inclusion) sizes and the locations. It leads to determination of the lower and upper boundary of the pipe grade PE lifetime in brittle fracture. 

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