In the past, most small diameter pipe welds were radiographed for defects. However, radiography has significant limitations: safety and licensing issues, disruption to work schedules, chemical wastes, and poor detection of planar defects. Manual ultrasonics was permitted by some codes, but suffers from lack of recorded data and dependence on the operator’s skills. Automated ultrasonic testing (...

Direct numerical simulation of three-dimensional (3D) viscous flow in a wavy pipe is performed using the lattice Boltzmann approach, to study 3D flow features in a curved pipe with nonuniform curvature. We first validate the lattice Boltzmann approach by simulating a transient flow in a straight pipe. In a wavy pipe, it is shown that the pressure gradient necessary to drive the flow depends mor...

A parametric study on circular thin-walled pipes subjected to pure bending is performed. Both straight and curved pipes are considered. Ratio D/t, initial pipe curvature and internal pressure are the parameters varying in the analyses. The study is mainly FEA-based. It is found that negative curvatures (opposite to bending moment) considerably increase stiffness and buckling limit of the pipe w...

We study boundary effects in a linear wave equation with Dirichlet type conditions in a weakly curved pipe. The coordinates in our pipe are prescribed by a given small curvature with finite range, while the pipe’s cross section being circular. Based on the straight pipe case a perturbative analysis by which the boundary value conditions are exactly satisfied is employed. As such an analysis we ...

A numerical study, using the volume-of-fluid method (VOF), has been made of core-annular flow in a curved pipe. We investigated two cases: core-annular flow in a 90◦ bend and in a 180◦ return bend. To verify our numerical method we first compared our results for a singlephase flow in a 90◦ bend with numerical results and experimental data given in the literature. The agreement was good. Thereaf...

A general robotic mechanism was presented for in-pipe inspection oflevel pipes with varied diameter or curved pipelines. The robot employed three legs comprised of parallelogram linkages mechanism which enables adapting to various elbow joints in the piping systems. The curvatures in pipeline are the most important constraints in front of the robot through navigation process. To study the adapt...

This paper describes computer modeling and testing of phased arrays curved in the passive axis to improve focusing on small diameter pipe welds; in practice, a couple of curvatures satisfy most diameter and wall thickness applications. The modeling was followed by experimental testing using one of the curved arrays. Not surprisingly, the curved array showed significant improvements over a flat ...

a general robotic mechanism was presented for in-pipe inspection oflevel pipes with varied diameter or curved pipelines. the robot employed three legs comprised of parallelogram linkages mechanism which enables adapting to various elbow joints in the piping systems. the curvatures in pipeline are the most important constraints in front of the robot through navigation process. to study the adapt...