What we do

CRES specializes in the integrity assessment of pipelines affected by anomalies, particularly weld anomalies, and extreme loading, such as that from geohazards and hydrotechnical hazards. Our work often involves the determination of safety margins and providing recommendations on operational decisions, such as pressure restrictions, safe dig pressures, prioritization of mitigation actions, and repair/mitigation options.

Integrity-Centric Geohazards Management

CRES offers integrity-centric approach for geohazards management that considers the natures of geohazards and the characteristics of a pipeline. The approach focuses on quantifiable safety margins of a pipeline affected by geohazards and interacting threats [1] by applying strain-based assessment (SBA) [2]. The safety margin is the difference (alternatively termed separation) of strain capacity [3] and strain demand. The need and priority of mitigation, methods of mitigation, and future action thresholds can be determined based on the safety margin [4]. The determination of the safety margin can involve conducting initial screening using our Gwise®-SBA software tool and performing targeted analysis and/or experimental testing for sites/conditions failing the initial screening.

Management of Circumferential Cracks (CC)

CRES offers software tool Gwise®-TSC which provides quick and accurate determination of tensile strain capacity (TSC) [5]. This tool, along with the determination of strain demand [6], is ideally suited for screening circumferential cracks, including pipe body circumferential SCC (C-SCC) and girth weld features reported by ILI. The strain demand is determined from direct or indirect measurements (e.g., strains and IMU) or using qualified values correlated to terrain and construction conditions in the absence of site-specific measurements. In addition to the screening, safe dig pressure, field dig procedure, and mitigation options can also be developed using the same SBA principles.

Management of Vintage Girth Welds

Girth welds in vintage pipes were not subjected to X-ray or other modern inspection methods at the time of construction. Flaws with dimensions greater than those permitted in modern pipeline construction standards, such as API 1104, can exist in those welds. CRES develops X-ray or UT flaw acceptance criteria using fitness-for-service (FFS) principles. These criteria are well suited for assessing the significance of the flaws without having to perform unnecessary repairs or cutouts which can have a negative impact on overall pipeline integrity. Corrosion interacting with girth welds can also assessed using the same principles and methodology. CRES also offers recommendations for mitigation methods tailored to specific pipeline characteristics and loading conditions.

Screening and Management of Low-Strain-Resistant Girth Welds

CRES provides screening and risk ranking for pipelines potentially affected by factors similar to those leading to known failures in relatively new pipelines [7],[8]. The risk ranking can be used for prioritizing mitigation actions when needed and for selecting appropriate mitigation methods.

Support for New Construction and Pipe Replacement Projects for Resilient Pipelines

CRES provides recommendations for enhanced linepipe specifications, selection of girth welding procedures, enhanced girth welding procedure qualification, flaw acceptance criteria, and construction stress management.

Burst Pressure Prediction of Axially-Oriented SCC (A-SCC)

The accuracy of burst pressure prediction for pipelines containing A-SCC can be strongly affected by flaw interaction rules. The intelligent flaw interaction rules developed by CRES have been shown to provide markedly improved accuracy and precision for burst pressure prediction [9]. CRES has a complete set of tools for burst pressure prediction using the intelligent flaw interaction rules, from an image recognition tool to create 3-D morphology of A-SCC colonies and a software algorithm to accurately account for interactions, to the selection of assessment models and determination of material parameters.

Metallurgical Analysis and Mechanical Tests

CRES provides a full suite of metallurgical analysis and mechanical tests that includes both conventional and purposedly-designed tests.

Failure and Root Cause Analysis

CRES provides comprehensive failure and root cause analysis by performing metallurgical examination/analysis, fractography, and specially-designed tests. Analytical/numerical methods are often used in parallel for the determination of failure mechanisms and contributing factors.

Assessment and Management of Pipeline Anomalies

CRES employs various tools for assessing the significance of anomalies found or suspected to exist in pipelines, including but not limited to mechanical damage, selective seam weld corrosion, general corrosion, and wrinkles/buckles. CRES conducts specially-designed tests and provides recommendations on inspection and mitigation for certain ERW pipes affected by pressure reversal and cold creep [10].

Determination of Tensile Strain Capacity (TSC)

CRES has a long and demonstrated history of leading the development and implementation of models and experimental tests for the determination of TSC. CRES provides a comprehensive suite of services for the determination of TSC of pipelines of all vintages, joint geometries (such as joints of different wall thicknesses and joints between pipe/pup to fittings), and joining/welding methods. The fundamental basis of the TSC determination is the validated multi-level PRCI-CRES tensile strain models [11]. The TSC is determined using our Gwise®-TSC tool or performing case-specific analysis and testing. CRES also provides procedures/processes tailored to pipeline operators for generating, collecting, and managing data/information critical for the determination of TSC.

Determination of Compressive Strain Capacity (CSC)

CRES uses the methodology in the validated CRES CSC models to determine the CSC [12] corresponding to maximum load or bending moment, CSC-ML [13]. The integrity of wrinkles/buckles is assessed using strain-driven fatigue models.

Determination of Strain Demand (SD)

CRES employs various approaches for the determination of SD. Particular attention is placed on the consistent representations of strain capacity and SD when processing IMU and strain gage data using our specialized tools. Simplified SD models and sophisticated pipe-soil interaction models are applied for the determination of SD [14].

Terms and Further Information

[1] Interacting threat in this context refers to threats that interact with geohazards, such as corrosion, seam weld flaws, circumferential cracks, mechanical damage, wrinkles, girth weld flaws, etc. at the same location of a pipeline affected by geohazard.
[2] More information about applying strain-based assessment method can found in this paper (presented at IPC 2024)
[3] Strain capacity is the maximum level of longitudinal/axial strain a pipe can sustain without undesirable consequences, such as a leak or rupture.
[4] An example for such application can be find in this IPC 2022 paper
[5] Tensile strain capacity (TSC) is the strain capacity in tensile.
[6] Strain demand is the longitudinal/axial strain imposed on the pipeline by its operational and surrounding conditions.
[7] More information about girth weld failures in newly construction pipelines can be found in this PRCI report and IPC paper
[8] Such as TC Energy Milepost14 incident
[9] More information about the intelligent flaw interaction rules and their applications can be found in this PPIM paper obtainable here and this IPC paper
[10] More about pressure reversal and cold creep tests can be found in this PPIM paper obtainable here
[11] More information about PRCI-CRES tensile strain models in IPC paper A, IPC paper B, IPC paper C.
[12] Compressive strain capacity (CSC) is the strain capacity in compression.
[13] CSC-ML is the CSC defined at the point of maximum load or maximum bending moment. Exceeding CSC-ML can lead to wrinkles or buckles.
[14] More information about various methods used for strain demand determination can be found in this IPC paper