Burst pressure assessment of pipe bend/elbow for transmission pipelines

Abstract

The pipelines for oil and gas transportation are generally laid along a straight route to avoid the complexity of pipe bending. However, changing of pipe alignment is sometimes unavoidable where a straight pipeline is mechanically bent, or two straight pipelines are connecting using a suitable pipe bend/elbow. In this study, the burst pressure of corroded and uncorroded pipe bends was investigated using finite element analysis. The study shows that the pipe bend reduces the burst pressure that depends extensively on the radius of the bend. A parametric study was conducted to identify the parameters affecting the burst pressure of the pipe bend. The parameters investigated included bend radius, bend angle, pipe dimensions, corrosion dimensions, location of corrosion, and the grade of the steel. Corrosion at the intrados of the bend was found to have the most adverse effect on the burst pressure of bend for pipes with lower bend radii. The ratio of the burst pressure of the pipe bend to the burst pressure of corresponding straight pipes depends on the bend radius and steel grade and is almost independent of the pipe and corrosion dimensions. This ratio can be used to assess the burst pressure of a pipe bend using the burst pressure of the corresponding straight pipe. However, for a bend radius greater than three times the pipe diameter, the burst pressure of pipe bend is almost the same as the burst pressure of the corresponding straight pipe.