Pipeline Material Properties

Pipeline Diameter

Pipeline Diameter

Diameter is generally well known for the main pipeline segment. However, a large number of laterals, fittings and appurtenances may be present on the pipeline for which the diameter is not well documented, such as station piping, offtakes, service taps, blow-offs, and so on. Although diameter is easily measured when access is available, verifying the diameter of buried components is more challenging.

Wall Thickness

Pipe Wall Thickness

Wall thickness is a direct determinant of safe operating pressure as one of the parameters within the design equation (for example, under 49 CFR 192.619 in the USA). Even more critical is the accuracy of wall thickness data when used to assess defects through remaining strength, predicted failure pressure, or remaining fatigue life calculations. On one hand, inaccurate data may lead to unsafe defects remaining in the pipeline or, on the other hand, over-conservatism may result in unnecessary repairs or reduced operating pressures.

Seam Type

Pipe Type or Seam Type

Identifying seamless or welded pipes is fundamental for a robust integrity management program. Once the ‘pipe type’ is known to be welded, further differentiation may be required with respect to the numerous different seam welding processes that have been used historically. These different weld types have different propensities to certain resident defect types or reduced resistance to fracture initiation and propagation, in particular vintage seam types such as low-frequency ERW, flash-welded and lap-welded pipe.

Pipe Grade

Pipe Grade

Pipe grade is a direct determinant of safe operating pressure as one of the parameters within the design equation (for example, under 49 CFR 192.619 in the USA).

Pipe grades are determined based on measurement of Yield Strength (YS) and Ultimate Tensile Strength (UTS) values. These values are critical inputs to remaining strength assessments and Predicted Failure Pressure (PFP) for metal loss and crack-like features respectively.

Toughness

Fracture Toughness

Toughness as a general term refers to a material’s tolerance to the presence of flaws. More specifically, fracture toughness is the material’s resistance to fracture propagation. Materials with a high fracture toughness can tolerate more severe cracks or crack-like defects at a given operating pressure without propagation of the feature.

For pipelines that contain or may be susceptible to cracks or crack-like features, accurate knowledge of the fracture toughness or Charpy data is critical since it can vary across a very wide range, from 1 Joule (or ft-lb) to several hundred Joules (ft-lbs). Additionally, operators must consider that toughness of the pipe body may be significantly different to that in the seam weld.

Toughness must be measured using destructive testing, for which the difficulty and cost of obtaining samples makes the process challenging. By implementing a clear and holistic strategy for Pipeline Material Verification, operators can minimize the cost and uncertainty involved in achieving complete and accurate data.

WHY IS MATERIAL VERIFICATION REQUIRED?

A robust knowledge of pipeline material properties and attributes is essential to support a safe operating pressure, as well as to underpin critical integrity management processes such as fitness for service, remaining strength or predicted failure pressure assessments.

When evaluating a pipeline’s suitability for service in hydrogen, or blended hydrogen, a fundamental step is to identify the different materials and pipe grades present to ensure compliance with codes, and to ensure that integrity management takes account of accurate material property inputs in the context of hydrogen-assisted degradation mechanisms.

For piggable pipelines, in-line inspection (ILI) technologies now permit operators to collect actual material property and attribute data from every pipe for up to 100% data completeness. The measurement principle for these ILI systems must now be well understood. Each system must provide discrete information on each pipe joint. For unpiggable pipelines, novel non-destructive techniques have made it feasible to measure pipe grade without removing pipes from service.

Operators can now take advantage of these technological and process-driven developments to achieve a step-change in the completeness and quality of the following data used within their integrity management programs.

After defining the strategic aims, the following key steps are particularly important to implement a Material Verification Program:

1. Gather all available data from multiple sources:
1. Identify and review existing pipeline records
2. Conduct in-line inspection (ILI) to provide material property and attribute data on every pipe
3. Conduct non-destructive (in-situ) testing to supplement and validate the ILI data
4. Perform destructive (laboratory) testing where required, e.g. for toughness data


2. Align and integrate the collected data to define traceable, verifiable and complete data for the pipe populations, material properties and attributes.
3. Implement the findings into the System of Record and Integrity Management Program.

Review and alignment of existing pipeline information

A comprehensive review and alignment of pipeline records (e.g. as-built drawings, pipe books, mill certificates, hydro test pressure records, etc.) provides an initial indication of the current status of compliance. Where required for regulatory compliance, the data must be categorized with respect to its TVC status.

The data from records can be used on its own to define populations and thereby progress to the next stages of the process. However, if the pipeline is piggable then data from previous inspections or planned inspections is invaluable in assessing the status of existing data, and supporting an accurate population assessment.

Pre-ILI Cleaning for increased first run success

At any stage of a pipeline system, debris can deposit and collect within the line. Especially in times when production decreases, resulting in reduced flow rates and increased accumulation of debris in the pipelines, cleaning prior to in-line inspections (ILI) is essential. The sensor technologies used in pipeline inspections require cleanliness to achieve reliable and accurate ILI results, resulting in high data quality and enabling accurate integrity assessments. This not only increases first run success, but also reduces operational risks and potential costs.

More about our Pipeline Cleaning services

Pipe Grade Sensors (PGS) for strength and pipe grade determination, and population assessment

ROSEN’s pipe grade sensors provide yield strength (YS) and ultimate tensile strength (UTS) for every pipe spool, which can be supported and validated by non-destructive in-field testing. This data can be used to verify existing records and expectations, or to provide data for areas with unknown grade. By collecting data on every pipe, outliers and rogue pipes can be detected down to the individual component level.

Equally as valuable is the population assessment provided. By evaluating the strength data in combination with other datasets reported by ILI, every pipe in the inspected section is grouped into a population of pipes with equivalent material properties and attributes. This comprehensive view of the different populations permits an optimized strategy to be implemented to close out the Material Verification Program.

More about our RoMat PGS service

MFL-A (axial magnetic flux leakage) for pipe type differentiation (seamless vs. welded)

The Magnetic Flux Leakage (MFL) technology is the right choice to reliably and effectively detect and characterize internal and external metal loss features. In addition, MFL-A can detect the presence of a seam weld or identify pipes as seamless. By combining this data with the population assessment, the confidence is increased further by considering groups of equivalent pipes in combination.

More about our RoCorr MFL-A service

Mechanical Dipper and Eddy Current (XT) for diameter determination

The XT technology, as a combination of mechanical caliper measurements with eddy current proximity sensors, provides unrivalled industry-renowned data sets of the highest quality for both liquid and gas pipelines. The dual-sensor technology applied enables precise mapping and sizing of ID anomalies by providing full circumferential and axial coverage. For visualization and modeling, detailed and accurate 3D representations of any geometric anomaly can be generated. Additional information includes the identification and characterization of bends and small changes in internal diameter, as well as the distinction to debris, scale or wax deposits. Combined with MFL technology, WT schedules can be accurately determined.

More about our RoGeo XT service

In-Field Validation Services

Verifying the in-line inspection (ILI) performance and the analysis process in the field using non-destructive, in-situ techniques, is an essential part of pipeline integrity management. Once collected, the results are reviewed and evaluated by subject matter experts with experience in material properties and testing to provide total confidence in material property and attribute verification.

More information on our In-Field Validation service

Lab Testing

Where material is already available, or it is feasible to remove samples from service, destructive laboratory testing provides the most accurate solution to determine material properties. For measurement of fracture toughness or Charpy testing, destructive testing is the only solution currently available. ROSEN’s test facility is able to conduct material characterization including tensile testing, chemical composition, metallography, and weld characterization.

More information on our Testing Facility

These technology solutions provide the means to gather all data necessary to close out the Material Verification Program and re-establish a comprehensive knowledge of the pipeline material properties. Each technology has its unique benefits and challenges and it is important to select the most appropriate combination of solutions to most efficiently progress through the process.

A significant amount of data may be generated that requires combined evaluation and interpretation. The different data sets must be considered in the context of their accuracy and limitations, and brought together to form a final assignment of material properties and attributes to fulfil regulatory requirements or to assimilate into the operator’s system of record for the pipeline.

DATA MANAGEMENT

As outlined above, more regulations now require that all pipeline records be traceable, verifiable and complete. With the amount of data steadily growing, the establishment of a system of record where all available data is readily accessible is becoming an increasingly critical issue for pipeline operators.

Our asset integrity management solution NIMA delivers the data you need, in the way that you need it, to make better integrity management decisions.

Find out more about NIMA