A New Approach to Control Running Fracture in Pipelines

Project Categories

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• Onshore Transmission Pipeline
• Fracture Analysis
• Pipeline Materials

Main Objective

Validation of the newly available direct assessment methodologies for both external corrosion and stress-corrosion cracking; development of improved modules for assisting operators with controlling the parameters that cause stress-corrosion cracking; approaches for improving the integrity of systems with wrinklebends and buckles; and a viable approach to running fracture that should help operators minimize its consequences when ruptures occur.
Goals:
(1) Develop and validate fracture arrestor design basis in reference to fracture speed, wall hoop stress and toughness, and gas properties;
(2) Quantify differences in flow properties, fracture initiation formulation, and backfill coefficient today vs initial empirical calibration, reformulate arrest model accordingly, and validate in reference to trends evident in full-scale test database;
(3) Characterize essential differences for modern high strength grades vs historic steels, such as elastic strain energy and dissipation near the fracture;
(4) Formulate a first-principles model reflecting active sources of dissipation;
(5) Establish the implications for a shift from fracture-controlled to flow-controlled running fracture as processes other than fracture become significant as toughness increases; and
(6) Quantify role of grade, yield to tensile ratio, toughness, and parameters that characterize line pipe properties and those of the transported product in reference to the fifth goal, and formulate a model for fracture arrest as the deliverable.
This is a consolidated project with Project No 162, Project No 163, and Project No 164.

Public Abstract

The Pipeline and Hazardous Materials Safety Administration is keenly interested in ensuring the safety of the nation's pipeline infrastructure. Battelle proposes a broad program that addresses several key elements of the complex but related issues that impact pipeline integrity to help meet this need. It is known that external and internal corrosion of buried pipelines receives much attention from operators. Stress-corrosion cracking and external corrosion have been implicated in several field failures. Consequently, Battelle has invested considerable effort to both understand and mitigate future related failures. We have also focused on other mechanisms that undermine integrity of vintage systems such as wrinklebends. Finally, ruptures occur occasionally when preventive measures taken to optimize pipeline integrity fail. In the worst of those cases, rupture propagates rapidly along the pipeline ("running fracture"), whose length controls the consequences of failure. Our proposal combines these elements into one project to provide higher value-added to the Government. Battelle's program comprises five projects previously submitted as separate white papers combined within the task structure of one program. The scope includes: validation of the newly available direct assessment methodologies for both external corrosion and stress-corrosion cracking; development of improved modules for assisting operators with controlling the parameters that cause stress-corrosion cracking; approaches for improving the integrity of systems with wrinklebends and buckles; and a viable approach to running fracture that should help operators minimize its consequences when ruptures occur.