Simulating Real-World Pipeline Conditions in a Full-Scale Destructive Test Lab

Introduction

Pipelines are a vital part of today’s energy infrastructure, and managing the integrity of North America’s aging systems remains one of the most significant challenges faced by engineers working for pipeline operators. This task becomes even more critical when considering the essential role pipelines play in supporting daily life across the continent. In addition to utilizing advanced inspection techniques and engineering assessments, full-scale testing offers a valuable tool for helping pipeline executives and integrity engineers make informed decisions about managing critical defects. Ultimately, full-scale testing serves to “sharpen the pencil,” ensuring that integrity investments are targeted where they deliver the greatest return on investment.

This article provides examples of full-scale testing used to evaluate the effects of dents, girth welds, wrinkle bends, and cracks on pipeline serviceability. It also discusses the creation of simulated defects and the techniques employed for their creation.

Simulated Defect Creation

Because there are a limited number of real-world features available for experimental assessment, testing often requires the creation of simulated features and defects. An important advantage in creating features is the ability to construct a well-defined test matrix that includes variations of key variables, including corrosion depth and length, dent depth, and crack depth and length.

Corrosion features can be fabricated using conventional machining techniques, electric discharge machining (EDM), and chemical etching to generate a pitted profile. Dents are fabricated by pressing an indenter into the pipe to a prescribed depth, often with internal pressure in the pipe. There are several techniques for fabricating axial cracks. However, one of the most repeatable involves the installation of an EDM notch into the pipe wall, followed by limited pressure cycling to generate cracking at the base of the notch. Girth weld defects have been created by grinding out a portion of the root pass during weld fabrication or, in the case of an existing girth weld, using an EDM notch to generate lack of penetration or incomplete penetration features.