On July 8, 2026, PHMSA published a Notice of Proposed Rulemaking (NPRM) for gas and hazardous liquid transmission pipelines. One notable aspect of the proposal was the inclusion of Dent Engineering Critical Assessment (ECA) requirements—despite the existence of Dent ECA provisions in 49 CFR §192.712(c).
The NPRM proposal serves three primary objectives:
- It responds to the D.C. Circuit Court’s remand of §192.712(c).
- It proposes a more prescriptive Dent ECA methodology.
- It extends Dent ECA requirements to hazardous liquid pipelines.
1. Background: The D.C. Circuit Required PHMSA to Revisit Dent ECA Requirements
The July 2026 NPRM is the result of a regulatory and legal process that began after PHMSA’s 2022 Gas Transmission Final Rule established Dent ECA requirements under §192.712(c).
In July 2023, INGAA filed a petition for review in the U.S. Court of Appeals for the D.C. Circuit challenging several aspects of the Dent ECA requirements. The challenge included PHMSA’s technical justification, cost-benefit analysis, prescribed methodology, reassessment safety factors, and implementation requirements. The Court subsequently remanded §192.712(c) to PHMSA for further consideration and directed the agency to address deficiencies in the rulemaking record.
The July 2026 NPRM is PHMSA’s response to the D.C. Circuit’s remand of §192.712(c).
2. PHMSA Is Proposing a More Prescriptive Dent ECA Process
A key aspect of the NPRM is PHMSA’s proposal to establish a more prescriptive framework for performing Dent ECAs. The proposal includes the following assessment elements:
- Identification of interacting threats
- Review of ILI data
- Comparison of historical dent profiles
- Load identification
- Curvature-based strain analysis
- Level 3 Finite Element Analysis (FEA)
- Fatigue-life estimation
- Crack-growth assessment where appropriate
Compared to the existing requirements in §192.712(c), the NPRM proposes a more detailed and prescriptive assessment process for operators relying on Dent ECAs.
The methodology outlined in the NPRM more closely resembles the technical approach associated with the 2008 Percy Priest Lake Special Permit. Elements such as historical ILI review, IMU strain analysis, dent geometry comparison, Level 3 FEA, and fatigue assessment mirror many of the technical components used in that report.
Pipeline operators would be expected to follow this proposed methodology when relying on Dent ECAs—instead of traditional depth-based criteria—as the technical basis for reassessment decisions.
3. PHMSA Is Extending Dent ECA Requirements to Hazardous Liquid Pipelines
Another significant aspect of the NPRM is the proposed introduction of Dent ECA requirements into the hazardous liquid pipeline regulations. Gas transmission pipelines already have Dent ECA provisions under §192.712(c). Hazardous liquid pipelines currently do not have an equivalent Dent ECA framework.
PHMSA’s NPRM proposes a new Dent ECA process in §195.415(c) that could be used as an alternative response methodology for dent conditions addressed in §195.453. The hazardous liquid Dent ECA framework would follow the same approach as gas transmission pipelines.
Two Important Technical Changes
Reassessment Safety Factors
The NPRM proposes a significant change to reassessment safety factors.
- For gas transmission pipelines, PHMSA proposes reducing the reassessment safety factor from 5 to 2.
- For hazardous liquid pipelines, PHMSA proposes implementing a reassessment safety factor of 5 as part of the new Dent ECA framework.
Increased Technical Rigor
For operators relying on Dent ECAs in lieu of depth-based response criteria, the proposal establishes a considerably more prescriptive dent assessment methodology through requirements such as curvature-based strain analysis, Level 3 FEA, fatigue-life estimation, and crack-growth assessment.
Important Takeaways
The July 2026 NPRM is PHMSA’s effort to:
- Respond to the D.C. Circuit’s remand of the existing Dent ECA provisions.
- Propose a more prescriptive and technically defined Dent ECA methodology.
- Extend Dent ECA requirements to hazardous liquid pipelines.
For operators relying on Dent ECAs, the proposed rule’s prescriptive assessment methodology will affect both reassessment planning and long-term integrity management strategies for gas and liquid pipelines.
Useful links:
NPRM July 8 2026: PHMSA-2025-0019-0035
eCFR :: 49 CFR 192.712 — Analysis of predicted failure pressure and critical strain level.