Understanding and Mitigating Hard Spots in Pipelines
Executive Summary (TLDR)
The Pipeline and Hazardous Materials Safety Administration (PHMSA) has recently issued Advisory Bulletin ADB-2024-01 to alert pipeline owners and operators about the risks associated with "hard spots" in pipelines, particularly those manufactured before 1970. These hard spots, resulting from manufacturing processes, can lead to hydrogen-induced cracking under certain conditions, posing significant safety and environmental risks. The bulletin recommends reviewing and re-evaluating historical pipeline data, enhancing inspection programs, and sharing information to manage this threat effectively.
On November 1, 2024, the Pipeline and Hazardous Materials Safety Administration (PHMSA) released Advisory Bulletin ADB-2024-01, addressing a crucial issue in pipeline integrity management: the presence of hard spots in pipeline steel. Subsequently, on November 18, 2024, PHMSA released Docket PHMSA-2024-0176. Let’s check out the details of the advisory, its implications for pipeline safety, and the recommended actions for operators.
Background on Hard Spots
Hard spots in pipelines are areas where the steel has become unusually hard due to localized cooling during the manufacturing process. Traditionally linked with pipes from A.O. Smith Corporation produced between 1948 and 1952, new research and incident analyses have expanded the scope to include pipes from other manufacturers up to the year 1970. These defects, while stable under normal conditions, can become hazardous when exposed to hydrogen, which can lead to cracking under operational stress.
Recent Incidents and Insights
Several incidents underscore the danger of hard spots:
On July 18, 2013, a 30-inch natural gas pipeline ruptured in Natchitoches, Louisiana. The pipe was manufactured in 1952 by A.O. Smith. Evidence suggested the failure was caused by hydrogen-induced cracking in a hard spot that was previously reinforced with a Type A sleeve. The leak, in this instance, was repaired with a Type B sleeve.
On January 14, 2015, a 30-inch natural gas pipeline ruptured in Brandon, Mississippi. The pipe was manufactured in 1952 by A.O. Smith. The failure was caused by hydrogen-induced cracking in a hard spot greater than two inches in length, previously reinforced with a Type A sleeve. Hardness testing could not be performed with the sleeve in place.
On August 1, 2019, a 30-inch natural gas pipeline ruptured in Danville, Kentucky. The pipe was manufactured in 1957 by A.O. Smith. The failure was caused by hydrogen-induced cracking in a hard spot. Hardness testing by the National Transportation Safety Board (NTSB) identified the origin hard spot was 5.85 inches by 3 inches, and had hardness values between 362 and 381 Brinell. Hardness readings extended through the pipe wall.
On February 13, 2022, an 18-inch natural gas pipeline ruptured in Perry County, Mississippi. The pipe was manufactured in 1950 by A.O. Smith. The failure was caused by hydrogen-induced cracking in a hard spot. Metallurgical testing found hardness values between 35 to 45 Rockwell, and was measured at approximately 0.6-inch by 2.5-inch.
On March 8, 2023, a 30-inch natural gas pipeline ruptured in Fauquier County, Virginia. The pipe was manufactured in 1957 by Bethlehem Steel. The failure was caused by hydrogen-induced cracking in a hard spot. Post incident ILI identified six hard spot features, and hardness values were confirmed from four features that ranged from 192-208 Brinell, which was slightly harder than base hardness (approximately 170 to 180 Brinell). In this instance, the operator did conduct a re-analysis of its data that resulted in updated results to identify the presence of additional hard spots.
Advanced Detection and Analysis
Advancements in in-line inspection (ILI) technology have allowed for more precise detection of hard spots. The NTSB investigation into the Danville incident revealed that initial ILI data from 2011, when re-analyzed in 2019, identified significantly more hard spots than previously detected, showcasing improvements in data analysis due to better software and hardware.
PHMSA's Recommendations
To address these findings, PHMSA advises the following:
Record Review. Operators should thoroughly review pipeline design and construction records to trace manufacturer details and manufacturing dates.
Susceptibility Assessment. Determine if pipelines are at risk based on manufacturer and production era.
Historical Integrity Issues. Look for patterns of known integrity failures that might be linked to hard spots.
Enhanced Assessment Programs. Develop programs for validating material hardness anomalies.
Re-evaluation of ILI Data. Use advanced analysis techniques to reassess past ILI data for potentially missed hard spots.
Information Sharing. Collaborate with the industry to discuss findings and mitigation strategies.
Operators are encouraged to take proactive measures in line with these recommendations to prevent incidents that could lead to safety hazards, environmental damage, or service disruptions. This advisory not only aims to prevent failures but also encourages a collaborative approach in the pipeline industry to share knowledge and best practices for managing hard spot risks.
Before You Go…
Ask yourself these three questions:
Do we have detailed records of our pipeline's manufacturing history, and are they sufficient to identify potential hard spot risks?
Have we ever re-evaluated our in-line inspection (ILI) data with newer technologies or methodologies to detect hard spots that might have been missed initially?
Are we actively participating in industry discussions and forums to share and gain knowledge about managing hard spots in pipelines?
Disclaimer: This is not legal advice and shall not be construed as such. You are encouraged to read the entire documents aforementioned to better understand the entirety of the information.
Interesting. Why, how are they exposed to hydrogen? Are they water lines or natural gas?