Abstract
Circumferential crack‑like features, including those associated with circumferential stress corrosion cracking (C‑SCC), present persistent integrity challenges for transmission pipelines. While non-welding repair technologies such as composite sleeves and steel compression sleeves are well established for axial flaws, a defined qualification basis for their application to circumferential flaws has not been available. This paper presents the outcomes from a multi‑phase Joint Industry Project (JIP) undertaken to address this gap.
The program evaluated the performance of non-welding repair technologies on circumferential flaws and developed a structured, repeatable methodology to support their qualification for field use. Phases 1 through 4 of the JIP implemented a comprehensive full‑scale test program under representative operating and loading conditions. Pipe sections containing machined circumferential flaws at 40%, 60%, and 80% wall loss were repaired using composite sleeves and steel compression sleeves, then subjected to combined internal pressure and axial tension. The results were compared against conventional Type-B sleeves. Repeatability was ensured by performing multiple tests using predefined performance metrics. Providing consistent testing conditions and repair length limitations for participating technologies allowed direct performance comparison.
The full‑scale biaxial testing was conducted on 12‑inch and 24‑inch pipe specimens representative of transmission pipelines. Displacement transducers were deployed to measure elongation of the repaired region, the base pipe spanning across the repaired region, and the base pipe remote from the repaired region. This instrumentation captured both global and local deformation responses during loading, enabling assessment of load transfer and stiffness behavior of the pipe and the influence of the repair.
The key performance metrics included stiffness across the repaired section in both elastic and plastic regimes relative to the unreinforced pipe; load‑carrying capacity of repaired versus unrepaired flawed pipes, defined as the maximum load sustained before loss of containment; and strain capacity comparisons across configurations. These metrics provided a quantitative basis for assessing repair effectiveness over multiple flaw severities and pipe diameters.
The results demonstrated that both non-welding repair technologies provide meaningful increases in stiffness, load-carrying capacity and strain capacity, and are capable of sustaining biaxial loading representative of service conditions. The outcomes support the technical viability of non‑welding sleeves for circumferential flaws and establish a foundation for a standardized qualification pathway. By formalizing test protocols and acceptance criteria, this work supports future incorporation into industry standards such as CSA Z662 and enables broader, more consistent application by operators.
This paper presents the qualification framework, test matrix, and key findings from Phases 1–4 of the JIP, offering practical guidance for operators and regulators seeking reliable non‑welding repair solutions for circumferential flaws.
Author:
Apps, Chris
Publisher:
ASME The American Society of Mechanical Engineers
2026 International Pipeline Conference
Year Published:
2026
Purchase Link:
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