Geohazard Strain Capacity Evaluation: a Girth Weld Anomaly Case Study

Tensile Strain Capacity Test

Stress Engineering Services (SES) performed a series of tests to determine the strain capacity of anomalies for a pipeline operating in a geohazard area. The line was designed based on strain capacity, but the effects of anomalies on the strain capacity was not well known. The results of the testing provided the operator crucial guidance in making integrity decisions for pipelines in known geohazard areas.

Details of the Test

Defects including simulated corrosion wall loss, dents and girth weld flaws were installed in pipe samples. Internal pressure was increased to the operating pressure and then axial tension was applied. The axial load was increased until failure occurred. Strains were measured using displacement transducers along with digital image correlation (“strain camera”).

Value of the Project

The testing generated an operating strain envelop for pipelines having anomalies. This allowed the operator to manage the integrity of the pipeline with the strain capacity in mind. The results were also used to validate numerical modeling of the anomalies.