June 2024, Vol. 251, No. 6
Features
Hydrogen-Blend Pipelines: Repurposing Requires Effective Data-Gathering Methods
By Ollie Burkinshaw, Principal Engineer, ROSEN Group, and Alistair Carvell, Innovation Analyst, National Gas Transmission
(P&GJ) — National Gas Transmission owns and operates the National Transmission System (NTS) in the UK and is working to play a leading role in the transition to a clean energy future.
National Gas Transmission, through Project Union, intends to repurpose approximately 1,243 miles (2,000 km) or 25% of the UK’s gas transmission pipelines by the early 2030s, creating a hydrogen “backbone” for the UK that connects to the European Hydrogen Backbone.
The NTS consists of more than 4,722 miles (7,600 km) of pipelines with diameters ranging from 4-inch to 48-inch (100 mm to 1,200 mm). Installation dates range from the late 1960s to the present, with 45% of the total network by length installed in the 1970s.
Pipelines Repurposing
To repurpose existing natural gas assets to hydrogen service, operators must conduct assessments to appraise their suitability and, once repurposed, implement effective integrity management programs to ensure continued safe operation.
These processes require a robust understanding of pipeline properties, risks, and susceptibility to integrity threats. Hydrogen service also drives the need for new datasets to be established or expanded, for example a particular focus on material performance in hydrogen environments.
For many pipelines, integrity management is currently based on secondary data, often no longer supported by high-quality or traceable records.
National Gas Transmission aims to re-establish high-quality data for such assets to ensure that repurposing assessments and future integrity management programs are based on accurate, complete and evidence-based data. The ambitious timescales planned for hydrogen repurposing mean that there is an urgent need for the relevant data to be established.
This article explores the approach taken by National Gas Transmission, supported by ROSEN, to:
- Develop a GIS database to efficiently manage and represent data to directly support engineering and risk assessments for hydrogen repurposing.
- Digitize pipeline data, supported by development of automated tools to extract data from records, inspection and testing.
- Quantify threats and capture new data relevant for hydrogen service, using a scope of advanced in-line inspection (ILI) supplemented by in-situ and destructive testing.
Efficient Data Processes
National Gas Transmission has extensive records, including original documentation from construction back to the 1960s and 70s. However, most of these records are archived in paper copies or microfiche films. Identifying a certain document for a specific asset from archived records is challenging, taking considerable time and manual effort.
This project is developing an efficient and reliable process centered around automated tools to extract data from scanned records and use this data to populate a geodatabase for pipelines and related assets. The result is a complete dataset with full traceability evidenced by hyperlinks to supporting documentation.
This process centers around three main solutions:
- Create an extended geodatabase structure to facilitate alignment and interrogation of data, overlaid with mapping of pipelines and related assets, down to the level of individual pipes, welds and components.
- Extract and digitize data from physical records and existing registers, using optical character recognition (OCR) and automated scripts.
- Complete inspection and testing to collect data required for hydrogen repurposing and fill any existing data gaps.
- The main aspects of the process are illustrated in Figure 1.
Value of GIS Solutions
Geographic Information Systems (GIS) provide a solution that combines a detailed database model with mapping of assets. Pipelines and other assets can be represented by both spatial and linear referencing and detailed data can be aligned to the assets with full granularity.
For pipelines, in-line inspection (ILI) provides direct mapping down to the level of individual pipes, components and welds. Although ILI does not capture data on above-ground installations (AGIs) a spatial representation of such assets can be facilitated by overlaying detailed drawings and aligning reference points with satellite imagery (Figure 2).
Wide-ranging extensions to the default Utility Pipeline Data Model (UPDM) schema were made to capture the datasets needed for hydrogen repurposing.
Each data entry is also accompanied by a simple classification according to the confidence level in the data and its suitability for use in repurposing assessments. The schema also adds the capability to reference applicable documentation, via direct hyperlinks, to evidence the sources of data.
Representing the data in this manner is an effective way to appraise the full range of relevant information for a specific asset, including information on the pipeline route, material properties and integrity threats. The functionality to easily query and summarize data is incorporated using Structured Query Language (SQL) within ArcGIS.
The use of dashboard views (Figure 3), provides an impactful overview of the data over the full asset or a selected segment. In this example, the pipeline is represented with open circles showing girth welds and colored circles showing the locations of metal loss and geometrical anomalies integrated from in-line inspection (ILI) data.
Charts are also used to provide a summary of the number of integrity threats, anomaly sizes, and their distribution along the pipeline for the selected segment.
Automated Data Extraction
A pipeline segment with a length of, say, 30 miles (50 km) will contain several thousand individual pipes, components and welds. Pipelines typically include multiple different areas of construction, attributes, and properties, resulting from design requirements and modifications that accumulate over time. This often results in a significant task to align and quantify data with high confidence.
Numerous types of records must be reviewed to achieve complete data suitable for the detailed engineering and risk assessments required to evidence suitability for hydrogen repurposing. This project is assessing data from a wide range of sources, including:
- Design details
- Route profile, location classes and sensitive areas
- Operational and monitoring data
- Manufacturing data and material properties
- Construction and welding records, procedure qualification and non-destructive examination (NDE)
- Hydrotest details
- Faults, incidents and repair history
- Inspection data from in-line inspection (ILI) or direct assessment
Although automated solutions are not always necessary, there are several cases where automation offers a substantial saving in time and manual effort, as well as reducing errors in data entry.
One of the clearest examples is in matching construction records with the supporting manufacturing documentation. The bar chart construction record extract (Figure 4) details the pipe grade and wall thickness for each pipe, as well as the “cast” or “heat” numbers associated with each of the several thousand pipes used to construct this pipeline segment. Optical character recognition (OCR) and automated scripts have been developed to extract these records into a digitized listing.
Manually identifying the manufacturing records for these heat numbers from an unstructured collection of thousands of scanned records is a significant task.
However, automation leveraging optical character recognition (OCR) and automated scripts can match the applicable records and populate hyperlinks to these against the digitized listing of pipes and components from construction records.
An engineer then checks the extracted data to ensure correctness and completeness. Once the review is complete, the listing is directly published to ArcGIS, using scripts to populate the database schema from the spreadsheet.
Advanced Inspections
Despite thorough records searches, there will inevitably be data gaps. Hydrogen service also drives the need for new datasets to be established or expanded. In particular, there is a focus on material properties in hydrogen gas environments, as well as the increased risk posed by the possible presence of cracks and crack-like defects.
To address these data requirements, a comprehensive inspection campaign using advanced in-line inspection (ILI) technologies has been completed for a 30-inch (750 mm), 22-mile (36-km) pipeline segment intended for hydrogen repurposing by National Gas Transmission, with inspection of further pipeline segments intended over the coming years as aligned with the overall hydrogen strategy.
The inspection incorporated the following advanced ILI services:
- Electromagnetic Acoustic Transducer (EMAT-C) and Circumferential Magnetic Flux Leakage (MFL-C) for detection of potential axial cracks and crack-like anomalies.
- The RoMat Pipe Grade Sensor (PGS) for verification of pipe strength grades and grouping pipes into ‘populations’ with equivalent properties and attributes.
- The RoMat Dual Magnetization (DMG) service to detect and size hardness anomalies, i.e., local areas with elevated hardness that could pose a threat in hydrogen service.
The definition of “populations” through the RoMat PGS service provides a clear breakdown of the pipeline into groups of pipes with the same grade, manufactured to the same process, and therefore possessing similar properties.
These populations provide a foundation upon which the findings of the inspection scope can be aligned in combination for this pipeline segment (Table 1). Note that the reported anomalies, particularly the potential crack-like anomalies and hardness anomalies, may require validation to confirm the nature of the features and ILI performance.
The data required to support the assessment of these identified integrity threats have been gathered using the information extracted from records and stored within the geodatabase in the process detailed earlier in this article. Where data does not have a sufficient confidence level or is not available, the need for further inspection and testing becomes clear.
In particular, in cases where potential cracks or crack-like anomalies are identified within specific populations, toughness data can be specifically gathered from the affected population(s) to support engineering calculations.
Bringing It All Together
This project has created efficient processes and tools to extract data from physical records and existing registers using automated processes. To add to existing data, a scope of advanced in-line inspection (ILI) was defined and completed on the first pipeline segment intended by National Gas Transmission for hydrogen repurposing.
These combined data have been integrated within an extended geodatabase structure, aligned with mapping of pipelines and related assets with full granularity down to individual pipes, components, and welds. This brings together information on the pipeline route, material properties, and integrity threats in a single system, enabling efficient management and interrogation of data.
Following these processes, future hydrogen repurposing assessments will benefit from complete information supported by direct links to data sources to evidence compliance.
The automated tools developed will accelerate the processes to achieve robust datasets essential to fully representative engineering and risk assessments, and the data will support effective integrity management programs for the remaining life of the pipeline.
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