{"operation":"document","citation":"P-25-005","title":"NTSB Safety Recommendation P-25-005","source_type":"guidance","agency":"National Transportation Safety Board","status":"guidance","official":true,"published_on":"2025-04-08","effective_on":"2025-04-08","summary":"TO THE 50 STATES, THE COMMONWEALTH OF PUERTO RICO, AND THE DISTRICT OF COLUMBIA: Require the installation of natural gas alarms that meet the specifications of National Fire Protection Association 715 in businesses, residences, and other buildings where people congregate that could be affected by a natural gas leak.","machine_formats":{"json":"https://regulus.evalyn.ai/document/ntsb-recommendation-p-25-005.json","markdown":"https://regulus.evalyn.ai/document/ntsb-recommendation-p-25-005.md"},"app_url":"https://regulus.evalyn.ai/document/ntsb-recommendation-p-25-005","source_url":"https://data.ntsb.gov/carol-main-public/sr-details/P-25-005","body":"NTSB safety recommendation P-25-005.\n\nTO THE 50 STATES, THE COMMONWEALTH OF PUERTO RICO, AND THE DISTRICT OF COLUMBIA: Require the installation of natural gas alarms that meet the specifications of National Fire Protection Association 715 in businesses, residences, and other buildings where people congregate that could be affected by a natural gas leak.\n\nPriority: CLASS II\n\nOverall Status: Open - Await Response\n\nIssued Date: 2025-04-08\n\nAdopted Date: 2025-03-18\n\nSynopsis: This report discusses the March 24, 2023, natural gas–fueled explosion and fire at Building 2 of the R.M. Palmer Company, a candy manufacturer located in West Reading, Pennsylvania. The explosion destroyed the manufacturer’s Building 2 and caused significant structural damage to its adjacent Building 1 and other surrounding structures. In total, 7 people were killed, 10 people were injured, and 3 families were displaced from a neighboring apartment building. Safety issues identified in this report include degradation of a retired service tee, insufficient consideration of threats to pipeline integrity, the risk associated with unmarked private pipeline assets crossing public rights-of-way (for example, a public street), delayed evacuation of Building 2 despite detection of natural gas, natural gas safety messaging that may not reach certain members of the public, insufficient guidance on gas leak emergency procedures, absence of natural gas detection alarms in commercial buildings, and insufficient accessibility of gas distribution line valves. As part of this investigation, the National Transportation Safety Board issued recommendations to the Pipeline and Hazardous Materials Safety Administration, the Occupational Safety and Health Administration, 50 states along with the Commonwealth of Puerto Rico and the District of Columbia, the Commonwealth of Pennsylvania, the Pennsylvania Public Utility Commission, the American Gas Association, the American Petroleum Institute, the Gas Piping Technology Committee, the Common Ground Alliance, the International Code Council, the National Fire Protection Association, UGI Corporation, and R.M. Palmer Company.\n\nProbable Cause: The National Transportation Safety Board determines that the probable cause of the explosion was degradation of a retired 1982 Aldyl A polyethylene service tee with a Delrin polyacetal insert that allowed natural gas to leak and migrate underground into the R.M. Palmer Company candy factory buildings, where it was ignited by an unknown source. Contributing to the degradation of the service tee and insert were significantly elevated ground temperatures from steam escaping R.M. Palmer Company’s corroded underground steam pipe, located near the service tee, that had been unmarked and cracked. Contributing to the steam pipe crack was soil movement and R.M. Palmer Company’s lack of awareness of the pipe’s corroded state. Contributing to the natural gas leak was UGI Corporation’s lack of awareness of the nearby steam pipe, which led to an incomplete integrity management program evaluation that did not consider or manage the risk posed by the steam pipe. Contributing to the accident’s severity was R.M. Palmer Company’s insufficient emergency response procedures and training of its employees, who did not understand the hazard and did not evacuate the buildings before the explosion.\n\nNtsbnumber: PLD23LR002\n\nReport Number: PIR-25-01\n\nAddressee Name: State of West Virginia\n\nAddressee Status: Open - Await Response\n\nAddressee Acronym: WV\n\nAddressee Organization Type: S-State Government\n\nCommunication Date: 2025-04-08\n\nCommunication Type: Transmittal Letter\n\nCommunication Contents: The National Transportation Safety Board (NTSB) is an independent federal agency charged by Congress with investigating every civil aviation accident in the United States and significant accidents in other modes of transportation—railroad, highway, marine, and pipeline. We determine the probable cause of the accidents and issue safety recommendations aimed at preventing future accidents. In addition, we carry out special studies concerning transportation safety and coordinate the resources of the federal government and other organizations to assist victims and their family members affected by major transportation disasters. We are providing the following information to urge the State of West Virginia to act on the safety recommendation in this letter because we believe your organization can help reduce the risk of future accidents. For more information about the NTSB and our recommendation process, please see the attached one-page summary. This letter also includes information about our March 18, 2025, report, UGI Corporation Natural Gas-Fueled Explosion and Fire, West Reading, Pennsylvania, March 24, 2023, NTSB/PIR-25/01. The details of this accident investigation and the resulting safety recommendations may be found in the attached report, which can also be accessed at http://www.ntsb.gov. As a result of this investigation, we identified the following safety issues: • Degradation of a retired Aldyl A service tee that was accelerated by elevated ground temperatures from a corroded and cracked steam pipe nearby. • UGI Corporation’s insufficient consideration of pipeline integrity threats, particularly Aldyl A service tees with Delrin inserts at elevated temperatures. • Presence of unmarked and unreported private assets crossing public rights-of-way, excluding them from the Pennsylvania One Call System and increasing the risk of damage to them. • Delayed evacuation of Palmer’s Building 2 despite detection of natural gas by employees and others. • Natural gas safety messaging from pipeline operator public awareness programs that may not reach certain members of the public. • Insufficient guidance on natural gas emergency procedures. • Absence of natural gas alarms in commercial buildings. • Insufficient accessibility of gas distribution line valves. Accordingly, the NTSB makes the following safety recommendation to the State of West Virginia (additional information regarding this recommendation can be found in the noted section of the report): • Require the installation of natural gas alarms that meet the specifications of National Fire Protection Association 715 in businesses, residences, and other buildings where people congregate that could be affected by a natural gas leak. (P-25-5) (See section 2.5.1.) The NTSB is vitally interested in this recommendation because it is designed to prevent accidents and save lives. We would appreciate a response within 90 days of the date of this letter, detailing the actions you have taken or intend to take to implement this recommendation. When replying, please refer to the safety recommendation by number (Safety Recommendation P-25-5). We encourage you to submit your response to ExecutiveSecretariat@ntsb.gov. If your reply, including attachments, exceeds 20 megabytes, please e mail us at the same address for instructions on how to send larger documents. Please do not submit both an electronic copy and a hard copy of the same response. All communications regarding safety recommendations are stored by the NTSB and viewable by the public. Please do not send privileged or confidential communications in response to this recommendation. Responses marked as confidential or privileged (or similar designations) will be considered nonresponsive. In the likely event that your company uses auto generated and/or preformatted confidentiality statements on letterhead or outgoing e-mails, please include a statement in your letter indicating that the information can be publicly released. If you have concerns about this protocol, please contact us at ExecutiveSecretariat@ntsb.gov. The attached letter from the NTSB Chairman provides information about the March 18, 2025, report UGI Corporation Natural Gas-Fueled Explosion and Fire, West Reading, Pennsylvania, March 24, 2023, PIR-25-1. The details of this accident investigation and the resulting safety recommendations may be found in the attached report, which can also be accessed at http://www.ntsb.gov. The NTSB is vitally interested in these recommendations because they are designed to prevent accidents and save lives. We would appreciate a response within 90 days of the date of this letter detailing the actions you have taken or intend to take to implement these recommendations. When replying, please refer to the safety recommendation by number (for example, P-25-5). We encourage you to submit your response to ExecutiveSecretariat@ntsb.gov. If your reply exceeds 20 megabytes, including attachments, please e mail us at the same address for instructions on how to send larger documents. Please do not submit both an electronic copy and a hard copy of the same response. From the report UGI Corporation Natural Gas-Fueled Explosion and Fire, West Reading, Pennsylvania, March 24, 2023, PIR-25-1: 2.5.1 Natural Gas Alarms Public awareness is an effective tool to encourage adoption of safety devices like natural gas alarms. The first edition of API RP 1162 requires that public awareness programs include safety messages about the awareness of hazards and prevention measures as well as leak recognition and response but does not specifically require these programs to disseminate safety messages about natural gas alarms. UGI’s public awareness materials distributed before the accident were consistent with federal regulations, and although the materials promoted the use of smoke and carbon monoxide alarms, they did not address natural gas alarms. Following the accident, UGI now includes safety messages encouraging the purchase of natural gas alarms in its public awareness materials. The NTSB concludes that installing natural gas alarms can alert people of a gas leak so they can evacuate the area; however, natural gas customers may not be aware of the necessity of such alarms. The NTSB believes that messages about the benefits of natural gas alarms are critically important and could save lives when natural gas alarms are installed. The NTSB further believes that the natural gas industry can help shape the effectiveness of public awareness program delivery methods so that people in businesses, schools, residences, and other places of congregation are better informed, both about natural gas hazards and the necessity of natural gas alarms. The American Gas Association, which represents natural gas pipeline operators throughout the US, can facilitate industry efforts to improve public awareness program delivery methods and to improve safety, most critically through increasing the installation of natural gas alarms. Therefore, the NTSB recommends that the American Gas Association share the details of the March 24, 2023, natural gas–fueled explosion and fire in West Reading, Pennsylvania, with its members, encouraging them to evaluate the effectiveness of their current delivery methods of public awareness programs and to promote the installation of natural gas alarms in businesses, residences, and other places of congregation that they serve. Evacuation should occur immediately upon detection of the presence of natural gas. In 1976, the NTSB made its first recommendation to require natural gas detection to provide early warning of leaks. Most recently, after a 2016 building explosion in Silver Spring, Maryland, and then again after the 2018 home explosion in Dallas, we made recommendations to the ICC and the NFPA to require natural gas alarms with methane detection in residences (NTSB 2019). We recommended the\n\nAddressee Acronym: WV\n\nAddressee Organization Type: S-State Government\n\nCommunication Date: 2026-04-07\n\nCommunication Type: Recommendation Mention\n\nCommunication Contents: Pipeline Investigation Report PIR-26-02, “Enbridge Inc. Natural Gas–Fueled Home Explosion and Fatality, South Jordan, Utah, November 6, 2024” published on April 7, 2026: 2 Analysis On November 6, 2024, a natural gas–fueled home explosion fatally injured one resident and damaged nearby homes. A crack in the 4-inch-diameter Aldyl A gas main near the home allowed natural gas to leak and fuel the home explosion. The NTSB found that the crack originated on the inner surface of the pipe and aligned directly with an oblong impression on the outer surface. Investigators determined that a rock impingement likely caused the oblong impression on the outer surface of the pipe and the resulting crack. They also found that the crack growth features indicated that the crack breached the outer surface in a single abrupt event. As a result, the pipe rapidly transitioned from releasing no gas to releasing up to 48.7 scfm, as measured in the lab. Footnote: The actual leak rate may have been lower, given that the pipeline was buried in soil, which would constrain the pipe and provide back-pressure resistance to gas as it leaked from the pipe. Post-explosion, subsurface gas readings showed that the natural gas migrated about 150 feet from the leak location to the home. Although the exact timing of the leak could not be determined, the residents’ observations of physical symptoms, inability to relight the basement water heater, and an unusually high candle flame before the accident suggest that natural gas may have been present in the home for at least 3 days before the explosion. On November 6, the flammable natural gas–air mixture ignited in the southwest quadrant of the basement. The Utah Deputy State Fire Marshal identified two possible sources of the ignition: a water heater and a furnace. The water heater was turned off at the control point, so the only credible ignition source was the furnace. Footnote: The furnace control valve was found postaccident to have significant thermal damage, consistent with it being the ignition source. Before the accident, Enbridge had implemented safeguards to mitigate the consequences of leaks, including periodic leak surveys, timely response to odor complaints, and targeted replacement projects. However, none of these strategies proved effective for this scenario, because of the following issues related to the strategies: • Periodic leak surveys. Regulators require distribution leak surveys to be conducted every 5 years. Enbridge conducted its most recent leak survey on April 29, 2022—two years before the accident. However, in this accident, through-wall crack propagation occurred too rapidly, causing the leak to go undetected before the explosion. • Timely response to odor complaints. Regulators require odorization of natural gas in distribution systems to help alert the public to natural gas leaks. During interviews conducted by investigators, the NTSB determined that the local residents had not smelled natural gas odorant near the accident home, even though gas was determined to have permeated the ground in the area during postaccident surveys, indicating that the odorant had been stripped from the leaked natural gas that ultimately entered the home. Footnote: Field testing of the gas in the distribution system after the explosion found acceptable odorant concentrations. Although odorant can act as an early warning of a gas release to prevent an explosion and fire, it has been known to become depleted when traveling through soil, as it did in this accident. Previous NTSB investigations have identified occurrences of odorant depletion that allowed natural gas leaks to go undetected, resulting in explosions in Dallas, Texas, in 2018 and in Silver Spring, Maryland, in 2016. Footnote: NTSB. 2021. Atmos Energy Corporation Natural Gas–Fueled Explosion, Dallas, Texas, February 23, 2018. PAR-21/01. Washington, DC: NTSB. Footnote: NTSB. 2019. Building Explosion and Fire, Silver Spring, Maryland, August 10, 2016. PAR-19/01. Washington, DC: NTSB. • Targeted replacement projects. A 2014 California Public Utilities Commission study showed that the vintage of Aldyl A present in this accident, with stress concentrations from rock impingement, squeeze-off, bending, or deflection, were statistically predicted to fail between 22 and 235 years after installation. Footnote: California Public Utilities Commission 2014 Hazard Analysis and Mitigation Report On Aldyl A Polyethylene Gas Pipelines in California. Haine 2014. Because the estimated failure time is imprecise (a range of more than 200 years), and because some environmental conditions—such as the locations of rocks in the backfill material—are unknown, the Enbridge evaluation of the cracking threat to the 1976 vintage Aldyl A did not accurately characterize the risk of rock impingements and prevented Enbridge from identifying effective mitigative actions and targeted replacement projects. Even though Enbridge worked continuously to search for the leak after the explosion, it took them more than 21 hours to find and isolate the natural gas leak. During this time, the pipeline continued to leak natural gas into the ground, increasing the risk to nearby residents, first responders, and others operating in the area. When an underground natural gas pipeline leak occurs rapidly, it can be difficult to safeguard against. Natural gas alarms can provide an early warning of natural gas leaks inside nearby structures and can alert the building occupants to take immediate safety actions. Had in-home natural gas alarms been installed in the homes involved in this accident, they would have alerted the residents to a potential problem and prompted them to evacuate and call 911, reducing or eliminating the fatal consequences of the explosion. The NTSB has previously recommended requiring the installation of natural gas alarms in businesses, residences, and other buildings (Safety Recommendation P 25 05).\n\nAddressee Acronym: WV\n\nAddressee Organization Type: S-State Government\n\nCommunication Date: 2026-06-05\n\nCommunication Type: Recommendation Mention\n\nCommunication Contents: Atmos Energy Corporation Natural Gas–Fueled Home Explosion Pipeline Investigation Report PIR-26-03 published on June 5, 2026: Analysis The explosion and fire occurred after natural gas leaked from a fractured buried main, migrated through an uncapped underground sewer lateral, entered the accident home, and reached an explosive concentration near an unknown ignition source. The investigation did not identify issues with gas pressures in the area of the leak or the timeliness or efficacy of the local emergency response agencies. Postaccident bar-hole testing and excavations found only one source of natural gas: a leak in the gas main near a valve box on the eastern edge of the construction site. On-site examinations of the main found that it was fractured around most of its circumference with a thin strip of metal at the top (12 o’clock position) joining the southern section of pipe to the section still threaded into the valve body. This indicates tension—a stretching force—at the bottom of the pipe along its long axis. Tension along the bottom of the pipe is consistent with a bending stress created by an external downward force. Based on information provided to Atmos by the construction superintendent, a cement truck ran over a valve box at the leak’s location immediately before he heard and smelled natural gas being released. The investigation did not identify another plausible external force that could have damaged the main. The Materials Laboratory examination of the main found fracture characteristics typical of fast crack growth and no signs of significant corrosion or preexisting structural damage that could have contributed to the failure. The fracture was therefore consistent with a sudden application of force by the valve box to the main. Based on the fracture’s location, timing, and fast-cracking characteristics, the valve box transmitted part of the cement truck’s weight to the gas main, causing the main to fracture and leak. Examination of the gas main and valve box involved in this accident found coal tar coating the main and deposited on the bottom edge of the valve box. This indicates that the valve box was in contact with the main. The presence of coal tar alone does not indicate when the contact occurred, but the evidence is consistent with the valve box being installed in contact with the main and therefore able transmit the cement truck’s weight directly to the main near the fracture’s location. Federal regulations at 49 CFR 192.181(c)(3) require that valve boxes not be installed in a manner that transmits external loads to mains, and valve boxes are normally installed with a buffer of soil or other protection between the valve box and the assets immediately below. For example, Atmos’s newer valve boxes are installed with support and base pads to prevent load transmission. However, Atmos was not actively replacing cast iron valve boxes with this newer design. Further, the maintenance crew that removed and reinstalled the valve box about 2 months before the accident did not have a specific standard to follow for reinstalling cast iron valve boxes other than an expectation that the top of the valve box be level with the grade. The lack of a standard likely led to the common reinstallation of valve boxes in contact with mains, as described by an Atmos vice president of operations. If Atmos had adopted either a standard for safely installing cast iron valve boxes or a policy of replacing cast iron valve boxes with the newer design, the protective buffer of soil or support pad would have reduced the load transmitted to the pipe on the day of the accident. There is not enough evidence to determine whether a buffer or pad would have prevented the accident, but it would have made the infrastructure more resilient. Atmos has not reported making changes to its valve box installation practices. After the main fractured, gas propagated undetected through an uncapped underground sewer lateral into the sewer system and then into the accident home, where it reached an explosive concentration. The gas in the sewers remained undetected because Atmos personnel did not test the atmosphere in the sewers prior to the explosion. For about 35 minutes, most of the time between the initial leak and the explosion, there was only one Atmos employee on the scene: an experienced senior service technician. He was equipped with a CGI and checked nearby storm drains for the presence of gas, which was one step in Atmos’s subsurface leak investigation procedure. During his interview with the NTSB, he described planning to check the sewers, another required step, but said that he had already confirmed that there was no threat to life or property. His activities after checking the storm drains are also consistent with a belief that he had finished assessing the risk posed by the leak: he switched to the non-safety-critical work of recording billing information for the damage. The investigation did not find evidence of a natural gas alarm in the accident home, which did not have gas service but was still impacted by a leak from a gas main. It is likely that a natural gas alarm would have provided the home’s occupants with warning of accumulating natural gas and given them an opportunity to evacuate before the explosion. The NTSB has advocated wider installation and use of natural gas alarms for nearly 50 years, including following the investigation into a pair of 2024 home explosions in Jackson, Mississippi, that involved Atmos assets. As a result of that investigation, the NTSB reiterated a recommendation to the 50 states, the Commonwealth of Puerto Rico, and the District of Columbia: Require the installation of natural gas alarms that meet the specifications of National Fire Protection Association 715 in businesses, residences, and other buildings where people congregate that could be affected by a natural gas leak. (P-25-5) Footnote: See CAROL for the complete history and current status of this recommendation. The NTSB also recommended that Atmos “develop and implement a program that makes natural gas alarms available to members of the public who reside in its distribution areas” (P-26-10).11F Footnote: See CAROL for the complete history and current status of this recommendation.\n\nAddressee Acronym: WV\n\nAddressee Organization Type: S-State Government\n\nCommunication Date: 2026-03-26\n\nCommunication Type: Recommendation Reiteration\n\nCommunication Contents: From the Report, “Atmos Energy Corporation Natural Gas-Fueled Home Explosions and Fires Jackson, Mississippi, January 24, 2024, and January 27, 2024” published on March 26, 2026. Absence of Natural Gas Detection Alarms in Buildings The Bristol Boulevard accident home and the Shalimar Drive accident home did not have natural gas alarms installed. For nearly 50 years, the NTSB has been recommending natural gas alarms for the early detection of natural gas leaks. In the West Reading accident, several candy factory employees told the NTSB that they had smelled natural gas odorant and did not call 9 1 1 or the gas company but stayed in the building until the explosion occurred. Some of the employees inquired with their managers about what to do, and their managers were equally unaware of the actions to take during a suspected natural gas leak. In the two Jackson accidents, and in many of the pipeline accidents the NTSB has investigated for the last 5 decades, people smelled natural gas odorant and either did not know what actions to take, or they knew the actions necessary to address a potential natural gas emergency but did not execute them. Natural gas distribution pipeline operators must educate the public on pipeline safety through public awareness programs. It is also necessary, however, to have safeguards in place when members of the public (1) smell natural gas odorant and do not take the appropriate safety actions and (2) do not smell natural gas odorant, as was the case in the NTSB investigation of the Dallas accident, and therefore do not take appropriate safety actions. Footnote: The NTSB’s Dallas investigation determined that the occupants in the accident homes did not smell natural gas odorant because it was absorbed and depleted in the soil. Natural gas alarms are safeguards in protecting the public, which is why the NTSB has recommended their installation after many of our pipeline accident investigations. The NTSB found that natural gas alarms likely would have prevented or reduced the consequences of the Dallas and West Reading accidents, and the evidence in this investigation suggests the same. The Shalimar Drive accident home was empty at the time of that accident; however, when the explosion in the Bristol Boulevard accident home occurred, two people were inside. Therefore, the NTSB concludes that had a natural gas alarm been installed inside the Bristol Boulevard accident home, it could have alerted occupants that natural gas was present, prompting them to evacuate and report the leak, making Atmos aware that the leak had likely worsened and required corrective action. As a result of the West Reading investigation, the NTSB recommended that the 50 States, the Commonwealth of Puerto Rico, and the District of Columbia: Require the installation of natural gas alarms that meet the specifications of National Fire Protection Association 715 in businesses, residences, and other buildings where people congregate that could be affected by a natural gas leak. (P-25-5) Footnote: Safety Recommendation P-25-5 is currently classified Open—Await Response. As of this report, 7 states and the District of Columbia have provided an initial response; 43 states and the Commonwealth of Puerto Rico have not responded. Footnote: The seven states that have provided an initial response include Colorado, Connecticut, Kansas, Nevada, North Carolina, Virginia, and Wyoming. Mississippi, the state where the two Jackson accidents occurred, is one of the 43 states that have not provided an initial response. The NTSB investigation of the two Jackson accidents has again identified the critical importance of natural gas alarms to alert occupants to natural gas leaks. Therefore, the NTSB reiterates Safety Recommendation P 25-5 to 50 States, the Commonwealth of Puerto Rico, and the District of Columbia. As discussed in section 1.10.1.1, after the Avondale accident, Atmos reported that it provided the public with information, through its website, on the availability of natural gas alarms. However, Atmos can do more to safeguard the public in its distribution areas. The NTSB is aware of multiple natural gas distribution operators that have made natural gas alarms available to people in their service areas. Footnote: Visit http://www.ntsb.gov to find additional information in the public docket for this NTSB accident investigation (case number PLD24FR003). Therefore, the NTSB recommends that Atmos develop and implement a program that makes natural gas alarms available to members of the public who reside in its distribution areas.\n\nAddressee Name: State of Washington\n\nAddressee Status: Open - Await Response\n\nAddressee Acronym: WA\n\nAddressee Organization Type: S-State Government\n\nCommunication Date: 2025-04-08\n\nCommunication Type: Transmittal Letter\n\nCommunication Contents: The National Transportation Safety Board (NTSB) is an independent federal agency charged by Congress with investigating every civil aviation accident in the United States and significant accidents in other modes of transportation—railroad, highway, marine, and pipeline. We determine the probable cause of the accidents and issue safety recommendations aimed at preventing future accidents. In addition, we carry out special studies concerning transportation safety and coordinate the resources of the federal government and other organizations to assist victims and their family members affected by major transportation disasters. We are providing the following information to urge the State of Washington to act on the safety recommendation in this letter because we believe your organization can help reduce the risk of future accidents. For more information about the NTSB and our recommendation process, please see the attached one-page summary. This letter also includes information about our March 18, 2025, report, UGI Corporation Natural Gas-Fueled Explosion and Fire, West Reading, Pennsylvania, March 24, 2023, NTSB/PIR-25/01. The details of this accident investigation and the resulting safety recommendations may be found in the attached report, which can also be accessed at http://www.ntsb.gov. As a result of this investigation, we identified the following safety issues: • Degradation of a retired Aldyl A service tee that was accelerated by elevated ground temperatures from a corroded and cracked steam pipe nearby. • UGI Corporation’s insufficient consideration of pipeline integrity threats, particularly Aldyl A service tees with Delrin inserts at elevated temperatures. • Presence of unmarked and unreported private assets crossing public rights-of-way, excluding them from the Pennsylvania One Call System and increasing the risk of damage to them. • Delayed evacuation of Palmer’s Building 2 despite detection of natural gas by employees and others. • Natural gas safety messaging from pipeline operator public awareness programs that may not reach certain members of the public. • Insufficient guidance on natural gas emergency procedures. • Absence of natural gas alarms in commercial buildings. • Insufficient accessibility of gas distribution line valves. Accordingly, the NTSB makes the following safety recommendation to the State of Washington (additional information regarding this recommendation can be found in the noted section of the report): • Require the installation of natural gas alarms that meet the specifications of National Fire Protection Association 715 in businesses, residences, and other buildings where people congregate that could be affected by a natural gas leak. (P-25-5) (See section 2.5.1.) The NTSB is vitally interested in this recommendation because it is designed to prevent accidents and save lives. We would appreciate a response within 90 days of the date of this letter, detailing the actions you have taken or intend to take to implement this recommendation. When replying, please refer to the safety recommendation by number (Safety Recommendation P-25-5). We encourage you to submit your response to ExecutiveSecretariat@ntsb.gov. If your reply, including attachments, exceeds 20 megabytes, please e mail us at the same address for instructions on how to send larger documents. Please do not submit both an electronic copy and a hard copy of the same response. All communications regarding safety recommendations are stored by the NTSB and viewable by the public. Please do not send privileged or confidential communications in response to this recommendation. Responses marked as confidential or privileged (or similar designations) will be considered nonresponsive. In the likely event that your company uses auto generated and/or preformatted confidentiality statements on letterhead or outgoing e-mails, please include a statement in your letter indicating that the information can be publicly released. If you have concerns about this protocol, please contact us at ExecutiveSecretariat@ntsb.gov. The attached letter from the NTSB Chairman provides information about the March 18, 2025, report UGI Corporation Natural Gas-Fueled Explosion and Fire, West Reading, Pennsylvania, March 24, 2023, PIR-25-1. The details of this accident investigation and the resulting safety recommendations may be found in the attached report, which can also be accessed at http://www.ntsb.gov. The NTSB is vitally interested in these recommendations because they are designed to prevent accidents and save lives. We would appreciate a response within 90 days of the date of this letter detailing the actions you have taken or intend to take to implement these recommendations. When replying, please refer to the safety recommendation by number (for example, P-25-5). We encourage you to submit your response to ExecutiveSecretariat@ntsb.gov. If your reply exceeds 20 megabytes, including attachments, please e mail us at the same address for instructions on how to send larger documents. Please do not submit both an electronic copy and a hard copy of the same response. From the report UGI Corporation Natural Gas-Fueled Explosion and Fire, West Reading, Pennsylvania, March 24, 2023, PIR-25-1: 2.5.1 Natural Gas Alarms Public awareness is an effective tool to encourage adoption of safety devices like natural gas alarms. The first edition of API RP 1162 requires that public awareness programs include safety messages about the awareness of hazards and prevention measures as well as leak recognition and response but does not specifically require these programs to disseminate safety messages about natural gas alarms. UGI’s public awareness materials distributed before the accident were consistent with federal regulations, and although the materials promoted the use of smoke and carbon monoxide alarms, they did not address natural gas alarms. Following the accident, UGI now includes safety messages encouraging the purchase of natural gas alarms in its public awareness materials. The NTSB concludes that installing natural gas alarms can alert people of a gas leak so they can evacuate the area; however, natural gas customers may not be aware of the necessity of such alarms. The NTSB believes that messages about the benefits of natural gas alarms are critically important and could save lives when natural gas alarms are installed. The NTSB further believes that the natural gas industry can help shape the effectiveness of public awareness program delivery methods so that people in businesses, schools, residences, and other places of congregation are better informed, both about natural gas hazards and the necessity of natural gas alarms. The American Gas Association, which represents natural gas pipeline operators throughout the US, can facilitate industry efforts to improve public awareness program delivery methods and to improve safety, most critically through increasing the installation of natural gas alarms. Therefore, the NTSB recommends that the American Gas Association share the details of the March 24, 2023, natural gas–fueled explosion and fire in West Reading, Pennsylvania, with its members, encouraging them to evaluate the effectiveness of their current delivery methods of public awareness programs and to promote the installation of natural gas alarms in businesses, residences, and other places of congregation that they serve. Evacuation should occur immediately upon detection of the presence of natural gas. In 1976, the NTSB made its first recommendation to require natural gas detection to provide early warning of leaks. Most recently, after a 2016 building explosion in Silver Spring, Maryland, and then again after the 2018 home explosion in Dallas, we made recommendations to the ICC and the NFPA to require natural gas alarms with methane detection in residences (NTSB 2019). We recommended the ICC w\n\nAddressee Acronym: WA\n\nAddressee Organization Type: S-State Government\n\nCommunication Date: 2026-04-07\n\nCommunication Type: Recommendation Mention\n\nCommunication Contents: Pipeline Investigation Report PIR-26-02, “Enbridge Inc. Natural Gas–Fueled Home Explosion and Fatality, South Jordan, Utah, November 6, 2024” published on April 7, 2026: 2 Analysis On November 6, 2024, a natural gas–fueled home explosion fatally injured one resident and damaged nearby homes. A crack in the 4-inch-diameter Aldyl A gas main near the home allowed natural gas to leak and fuel the home explosion. The NTSB found that the crack originated on the inner surface of the pipe and aligned directly with an oblong impression on the outer surface. Investigators determined that a rock impingement likely caused the oblong impression on the outer surface of the pipe and the resulting crack. They also found that the crack growth features indicated that the crack breached the outer surface in a single abrupt event. As a result, the pipe rapidly transitioned from releasing no gas to releasing up to 48.7 scfm, as measured in the lab. Footnote: The actual leak rate may have been lower, given that the pipeline was buried in soil, which would constrain the pipe and provide back-pressure resistance to gas as it leaked from the pipe. Post-explosion, subsurface gas readings showed that the natural gas migrated about 150 feet from the leak location to the home. Although the exact timing of the leak could not be determined, the residents’ observations of physical symptoms, inability to relight the basement water heater, and an unusually high candle flame before the accident suggest that natural gas may have been present in the home for at least 3 days before the explosion. On November 6, the flammable natural gas–air mixture ignited in the southwest quadrant of the basement. The Utah Deputy State Fire Marshal identified two possible sources of the ignition: a water heater and a furnace. The water heater was turned off at the control point, so the only credible ignition source was the furnace. Footnote: The furnace control valve was found postaccident to have significant thermal damage, consistent with it being the ignition source. Before the accident, Enbridge had implemented safeguards to mitigate the consequences of leaks, including periodic leak surveys, timely response to odor complaints, and targeted replacement projects. However, none of these strategies proved effective for this scenario, because of the following issues related to the strategies: • Periodic leak surveys. Regulators require distribution leak surveys to be conducted every 5 years. Enbridge conducted its most recent leak survey on April 29, 2022—two years before the accident. However, in this accident, through-wall crack propagation occurred too rapidly, causing the leak to go undetected before the explosion. • Timely response to odor comp","truncated":true,"body_characters":1385695}