Class Location Change – a Key Driver for Applying Engineering Assessments
Both Engineering Assessments (EA), as outlined in the CSA Z662 Canadian Oil & Gas Pipeline Standard and Engineering Critical Assessments (ECA), as outlined in the 49 CFR Part 192 US Gas Mega Rule are expected to be increasingly relied upon for demonstrating fitness-for-service and required safety levels to stakeholders including the public, regulators, customers, and the internal operating organization. These performance-based assessments will ensure that resources are focused on efforts that measurably increase safety and reliability performance and that pipeline replacement and pressure reduction actions are efficiently directed.
Engineering Assessment as defined in CSA Z662:19
An engineering assessment is a documented assessment of the effect of relevant variables upon fitness- for-service or integrity of a pipeline system, using engineering principles, conducted by, or under the direct supervision of, a competent person with demonstrated understanding and experience in the application of the engineering and risk management principles related to the issue being assessed.
Engineering Critical Assessment as defined in 49 CFR Part 192 Gas Mega Rule
An engineering critical assessment is a documented analytical procedure based on fracture mechanics principles, relevant material properties (mechanical and fracture resistance properties), operating history, operational environment, in-service degradation, possible failure mechanisms, initial and final defect sizes, and usage of future operating and maintenance procedures to determine the maximum tolerable sizes for imperfections based upon the pipeline segment maximum allowable operating pressure.
In summary, regardless of if we are talking about the Canadian Standard EA or the US Code ECA, these are both detailed fitness-for-service assessments which can consider various threats and defect types.
The circumstances for and the use of EAs and ECAs are converging in Canada and the US including, but not limited to:
- Class location designation change
- MOP or MAOP upgrade
- Defect assessment or evaluation of damage
- Flow reversal or change in service
- MAOP reconfirmation (US)
- Special permits (US)
- Return to service
Class Location Designation Changes
Class Location Designation Changes are expected to continue to be a key driver for EAs and ECAs in both Canada and the US, respectively.
CSA Z662 requires a conformance check to five key elements (mainly design related) for pipe in a Class Location Designation Change area. This includes the design factor or location factor, valve spacing, depth of cover, pressure testing and evaluation and repair of imperfections.
While there is provision for engineering assessments to be carried out if one of the five elements cannot be met, it is acknowledged that deviations from design-based elements can create a challenge for gaining stakeholder approval and can result in replacement or pressure reduction actions that are not necessarily performance-based or measurably improve pipeline reliability and safety.
CSA Z662:23 Proposed Updates
The CSA Z662 Risk Management Task Force has developed proposed, quantitative Safety Risk and Environmental Risk acceptance guidelines for the 2023 Standard (Standard not yet approved) as part of the non-mandatory Risk Management Annex (Annex B). These risk acceptance thresholds are expected to be a useful tool in demonstrating pipeline safety to stakeholders in the context of both pipeline risk assessments and engineering assessments.
It is noted that quantitative risk acceptance criteria are also of interest to the US regulatory bodies and have also been explored through recent PHMSA industry studies and work groups related to quantitative risk modeling and risk tolerance thresholds.
A risk-based approach that demonstrates an acceptable risk level can provide a path forward for a successful and reliable engineering assessment that provides a performance-based validation of pipeline reliability and safety to stakeholders.
Contact us today to discuss how our team of experts can best support Transmission and Midstream Operator’s regulatory compliance through dedicated EAs and ECAs for safe and efficient pipeline operations.