Risk-informed and uncertainty-aware strain capacity prediction model development and verification for vintage pipelines

Overview

Main Objective

This project aims at developing a validated, risk-informed, and uncertainty-aware framework for quantifying strain capacity and associated uncertainty in vintage pipeline systems under displacement-controlled loading. The proposed work integrates targeted experimental testing, fracture characterization, high-fidelity numerical simulation, probabilistic modeling, and Bayesian inference. Emphasis will be placed on addressing the uncertainty and risk involved in applying strain-based design and assessment (SBDA) models to vintage pipeline systems, which exhibit significantly different flaw characteristics and uncertain material behavior. This collaborative effort leverages the team's collective expertise in material testing, computational modeling, fracture mechanics, geotechnical engineering, uncertainty quantification, and risk assessment to address this critical research gap.

Anticipated Result: This project will deliver: 1) A validated probabilistic model to estimate pipeline strain capacity for vintage systems; 2) A vintage-specific testing data repository and a numerical simulation database; 3) A model framework for incorporating uncertainty and risk metrics into strain-based fitness-for-service assessments for vintage pipelines.

Public Abstract

Vintage pipelines, many constructed prior to 1970, constitute a substantial portion of the U.S. transmission network and present distinct material, welding, and inspection characteristics compared to modern pipelines. These systems frequently incorporate manual shielded metal arc welds (SMAW), low-toughness steels, undocumented or less documented welding procedures, and flaw morphologies inconsistent with modern fabrication standards. While several highly capable and validated strain capacity models designed for vintage assets exist, the primary gaps are lacking consideration of uncertainties involved in both vintage systems (aleatoric) and predictive model parameters (epistemic). To address these critical gaps, this project proposes the development of a comprehensive and validated framework for predicting the strain capacity of vintage pipelines with quantified uncertainty. This effort will combine mechanical testing, advanced finite element simulations, and probabilistic modeling tailored to the variability of the distinct mechanical behavior and flaw characteristics of vintage systems. Finite element analysis (FEA) will be employed to simulate different loading scenarios and evaluate strain localization, girth weld flaw interaction, and fracture response under displacement-controlled loading conditions according to an FEA case matrix. The numerical model will be calibrated and validated using lab testing data. A Bayesian uncertainty quantification framework will be integrated into the physics-informed strain capacity model from both experimental and simulation data, enabling probabilistic strain capacity predictions and estimation of failure likelihood. This risk-informed approach will support decision making under uncertainties by linking strain capacity model to probability-of-failure metric and integrity management thresholds. The outcome will be a vintage-specific, uncertainty-aware strain capacity assessment tool that improves the credibility, transparency, and effectiveness of integrity evaluations for aging pipeline systems. This work directly aligns with PHMSA's goals to enhance pipeline safety and optimize risk management for legacy infrastructure.

Potential Impact on Safety: By advancing SBDA for vintage systems, this research will provide uncertainty quantification to existing assessment methods for vintage pipelines, minimize unnecessary remediation actions, and enable targeted integrity management decisions. Incorporating quantified uncertainty into strain capacity predictions will also enhance pipeline risk By advancing SBDA for vintage systems, this research will provide uncertainty quantification to existing assessment methods for vintage pipelines, minimize unnecessary remediation actions, and enable targeted integrity management decisions. Incorporating quantified uncertainty into strain capacity predictions will also enhance pipeline risk