GIS Data Integrity and Pipeline Safety
Did you know, in the early days of oil transportation, the barrels were specifically built to account for about a 5% loss in transit? Oil barrels were meant to transport 42 gallons but were built to hold 44 gallons. Talk about inefficiency.
Today, most oil, natural gas and other hydrocarbon products are transported via pipelines. Pipelines are the safest, efficient, and most economical method to connect producing areas to refineries and the end consumers. This vast complex network, over 200,000 miles in the US alone, safely delivers liquid and gas hydrocarbon products to rural and urban homes and businesses 24 hours a day.
San Bruno Accident
On September 9, 2010, just after 6 PM, a 30-inch segment of the PG&E natural gas pipeline raptured triggering an eruption. The blast and subsequent fire in a residential neighbourhood took the lives of 8 people and burned 38 homes to the ground.
According to NTSB (National Transportation Safety Board), the probable cause of the deadly PG&E pipeline blast was a defective seam in the pipe segment that blew up. A substandard pipe section was installed and poor welded. The seam was incorrectly listed in the records as seamless.
Another probable cause that NTSB brought up was PG&E’s inadequate pipeline integrity management program. The program failed to detect and repair/remove the defective section.
Pipeline Integrity Management Program
The majority of the pipelines are buried underground making it hard to see when deteriorating and becoming prone to failure. For that reason, pipeline operators are required by PHMSA -Pipeline and Hazardous Material Safety Administration to develop and implement comprehensive integrity management programs.
A pipeline integrity management program manages methods, tools and activities for assessing pipeline integrity. This is to determine whether their pipelines have adequate strength to prevent raptures under normal operation and upset conditions.
There are several methods to determine pipeline integrity. Most common methods include:
- Hydrostatic testing: Process in which pipeline is tested for strength and leaks. It involves filling the pipeline with water, removing the contained air and pressuring it up to 1.5 times its design pressure. The pressure is then held and monitored for a specific amount of time.
- In-line inspection: This process involves deploying inspection tools, ‘smart pigs’, through a pipeline. The tools measure and record the size and location of any irregularities like cracks, metal loss, dents or any other defects.
- Direct Assessment: A four-phase process for inspecting internal corrosion, external corrosion and stress corrosion cracking of pipelines.
Pipeline assessment reports show the location and severity of dents, cracks, metal loss, and other deformities in the pipeline. Operators use the reports to identify short-term and long-term integrity threats and, following stipulations by regulators, prioritize necessary repairs. The process is repeated periodically to make sure the pipelines remain safe and strong.
The continuous safety of these pipelines depends heavily on data quality.
Data Integrity is the overall accuracy, completeness, and consistency of data stored in a database. This is achieved by:
Making sure personnel responsible for data entry are well trained and accountable for the quality of data input.
Have validation rules in place to restrict and control values entered into the system (eg. Specifying data types and use of drop-down lists, version-based editing).
Implementing regular maintenance routines (eg. pre-post version reconciliation, weekly/monthly production database backups)
Mandates after San Bruno Accident
One of the issues that came to the surface after the San Bruno accident, was that PG&E did not have records to identify with any certainty what was buried underground for many of their pipelines. This was also the case for many operators.
After the San Bruno accident, an overhaul of safety regulations was called in efforts to prevent similar disasters from occurring in the future. Key among these were:
- The limiting applicability of the ‘grandfather clause’. The clause allowed operators of pipeline installed before 1970 to establish operating pressure on the basis of history-no test records were required.
- Bill requires companies to keep better records detailing maximum pressure levels their pipelines can safely handle.
PG&E system had not been inspected for many years
Role of GIS
As part of its most wanted list of transportation safety improvement, NTSB issued P-15–22. Recommendation for the pipeline industry to develop and implement a plan to improve data integration for integrity management through the use of geographic information systems.
For oil and gas companies, their GIS contain information on location along with attribute data of their physical features like pipelines, pump stations, valves, fittings, and other features. The systems also contain references to construction drawings, work orders, inspection records, material heat numbers, and other tests. The integration of GIS and other data management systems ensures the availability of additional information for monitoring pipeline integrity, helping in improving the safety of pipeline operations.
Many enterprises restrict the data input to the system by only allowing the GIS group to input and edit spatial information thus establishing ‘Single Source of Truth’.
Versioning is another way of error checking and data validation. Versioning allows multiple users to concurrently edit a geodatabase. Users are required to reconcile their edits and resolve any conflicts before posting them to the parent database.
Growing safety and compliance pressures driven by high profile incidents and the increasing role of GIS in pipeline safety underscores the importance of quality of pipeline integrity data. Pipeline operators will continue relying on accurate spatial data to improve management of pipeline integrity and comply with safety regulations.
What is your organization doing to make sure your geodatabase is accurate and up-to-date?