PHMSA Compliance Analysis 2025

Pipeline Incident Causes: Key Insights

Pipeline incidents are categorized into seven high-level causes by PHMSA: corrosion, excavation damage, incorrect operation, equipment failure, material/weld failure, natural force damage, and outside force damage. This analysis delves into the predominant causes for different pipeline types.

Hazardous liquid pipelines: Equipment failure (45%) and corrosion (25%) are leading causes (2023 data).
Gas transmission pipelines: Third-party excavation, external corrosion, material failure, and internal corrosion collectively account for over 75% of incidents (2002-2013 data).
Gas distribution pipelines: Older data (1999-2003) points to excavation/mechanical damage (38%) and outside force damage (29%) as primary causes.
Detailed subcategories like O&M manual issues or operator qualification problems are often subsumed under broader categories, limiting granular analysis.

Hazardous Liquid Pipelines: Incident Causes

Incidents involving hazardous liquid pipelines (crude oil and refined products) are predominantly caused by equipment failure and corrosion. The chart below illustrates the breakdown of causes based on the 2023 Liquid Energy Pipeline Association (LEPA) Performance Report data for 2020-2024.

Key Trends & Details:

Cause	Percentage
Equipment Failure	45%
Corrosion Failure	25%
Incorrect Operation	12%
Material Pipe/Weld Failure	6%
Excavation Damage	2%
Other Causes	10%

The LEPA report indicates a 33% reduction in integrity management incidents (corrosion, cracking) and a 22% decrease in operations and maintenance incidents (equipment failure, excavation due to insufficient locating) from 2020 to 2024.

Gas Transmission Pipelines: Incident Causes

For long-distance gas transmission pipelines, incidents are primarily driven by a few dominant causes. A study analyzing PHMSA data from 2002 to 2013 highlights that a combination of third-party excavation, external corrosion, material failure, and internal corrosion accounts for over 75% of incidents.

These pipelines face unique challenges due to their extensive reach and exposure to external factors. External corrosion is particularly significant for pipeline ruptures.

Gas Distribution Pipelines: Incident Causes

Gas distribution pipelines, operating in urban and suburban areas, are highly susceptible to incidents from third-party interference. While the data is older (1999-2003 PHMSA report), it highlights consistent patterns of causes.

Key Patterns:

Excavation/Mechanical Damage is the leading cause, with 91% attributed to third-party activities, often linked to insufficient pipeline locating and One-Call adherence.
Other Outside Force Damage includes vehicle-related incidents (11%) and fire/explosion as primary causes (11%).
The high prevalence of these causes reflects the urban settings where these pipelines are located, increasing the risk of external interference.
More recent specific percentage data is limited, but equipment failure, operator error, and corrosion remain significant general causes.

Data Quality and Limitations

The analysis relies on publicly available data, which presents certain limitations:

Granular Subcategories: The data often lacks highly specific subcategories, such as detailed issues with O&M manuals or operator qualifications. These are likely embedded within broader categories like "incorrect operation" or "equipment failure."
Data Accessibility: Accessing more granular data (e.g., PHMSA's detailed incident report files with subcause fields) was not feasible for this analysis, as it typically requires downloading large datasets.
Completeness and Age: Concerns about data completeness, particularly for certain segments like gas gathering lines (only ~5% regulated by PHMSA), may lead to underreporting. Additionally, some data, especially for gas distribution, is older (e.g., 1999-2003), limiting its applicability to current conditions.

Despite these limitations, the consistency of high-level causes across different pipeline types and over time suggests enduring patterns in incident causation.

Regulatory & Safety Measures

PHMSA enforces pipeline safety through regulations and mandates, complemented by ongoing industry efforts to enhance safety performance.

PHMSA Oversight

PHMSA mandates operators to submit incident reports (under 49 CFR Parts 191 & 195) within 30 days and implement rigorous integrity management programs.

These programs are crucial for assessing and mitigating risks, especially in high-consequence areas, through systematic inspections and maintenance.

Industry Initiatives

Industry associations like AGA and INGAA collaborate on performance measures, promoting best practices in materials, inspection technologies, and operational protocols.

Public awareness campaigns, such as "Call 811 before you dig," are vital for preventing third-party excavation damage, a common cause across all pipeline types.

The AGA reports a 40% decline in pipeline incidents over the past decade, reflecting advancements in safety practices.

Conclusion & Key Citations

Understanding the diverse causes of pipeline incidents across different pipeline types is essential for targeted safety improvements. While equipment failure and corrosion are major concerns for liquid pipelines, external interference and aging infrastructure remain critical for natural gas networks. Ongoing regulatory oversight and industry commitment are key to further enhancing pipeline safety.