Welding quality control is an important parameter for safe operation of oil and gas pipes, especially for high-strength steel pipes. Size control of welding defect is a bottleneck problem for current pipe construction. As a key part of construction procedure for butt-welding of pipes, pore defects in girth weld is difficult to ignore. A three-dimensional non-linear finite element numerical mode...

Installation of new pipelines is predicted to grow at a rapid rate over the next twenty years, due in part to the increase use worldwide of combined cycle power generation plant using natural gas a fuel. The need to construct large diameter pipelines over long distances has led to an increased demand to improve the productivity of pipeline girth welding. Many novel techniques have been tried in...

In order to achieve integrated condition in the girth welding of high pressure natural gas transmission pipelines, the weld zones and its surrounding area should have good mechanical properties. Residual stresses are an important defect especially in the girth welding of the pipeline. In this study, two API X70 steel pipes (with spiral seam weld) of 56 inches outside diameter and 0.780 inch wal...

We discuss the construction of snarks (that is, cyclically 4-edge connected cubic graphs of girth at least five which are not 3-edge colourable) by using what we call colourable snark units and a welding process.

Economical design with sufficient fracture resistance is of high importance in any offshore pipeline projects. Using an Engineering Critical Assessment (ECA), alternate acceptance criteria for pipeline girth weld inspection can significantly reduce the cost of constructing of offshore oil and gas pipeline by minimizing unnecessary repairs. Offshore pipelines consist of short pipeline segments c...

This article studies the multi-layer and multi-pass welding of circumferential weld in thick pipe an aviation enterprise, based on static characteristics arc, through data calculations experiments to verify relationship between arc voltage length, proposes use controller accurately adjust real time, improve stability, torch wiggler expand fusion width, meet adaptive adjustment wide weld, build ...

Girth welded replica of API X70M material have been produced on NG-GMAW welding technique. The particular area interest is to develop suitable girth process parameter using NGGMAW. major aim the work was replicate welds having tensile strength between 650 and 680 MPa. Design Experiment (DoE) method by Taguchi design, some selected processes adopted. Two parameters (factors) – arc voltage wire f...

Three-dimensional finite element modeling of residual stresses in a girth-welded pipe is presented in this paper, with an emphasis on modeling procedures for the global residual stress characteristics. The shell element model with a heat source moving along the circumferential joint is demonstrated to be cost effective and capable of predicting the global residual stress features. Transient res...