NTSB Safety Recommendation P-25-008

NTSB safety recommendation P-25-008.

TO THE PENNSYLVANIA PUBLIC UTILITY COMMISSION: Assess the methodology used by natural gas pipeline operators to determine where emergency valves should be located to ensure the operators are properly considering consequences and emergency response times as well as population sizes.

Priority: CLASS II

Overall Status: Open - Acceptable Response

Issued Date: 2025-04-08

Adopted Date: 2025-03-18

Synopsis: 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.

Probable 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.

Ntsbnumber: PLD23LR002

Report Number: PIR-25-01

Addressee Name: Commonwealth of Pennsylvania, Public Utility Commission

Addressee Status: Open - Acceptable Response

Addressee Acronym: PA PUC

Addressee Organization Type: S-State Government

Communication Date: 2025-04-08

Communication Type: Transmittal Letter

Communication 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 Pennsylvania Public Utility Commission 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 Pennsylvania Public Utility Commission (additional information regarding this recommendation can be found in the noted section of the report): • Assess the methodology used by natural gas pipeline operators to determine where emergency valves should be located to ensure the operators are properly considering consequences and emergency response times as well as population sizes. (P-25-8) (See section 2.6.) 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-25-8). 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 organization 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 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 (for example, P-25-8). 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: 2.6 Valve Accessibility During a natural gas emergency such as an explosion or fire, valves along the gas distribution lines are operated to shut off the flow of gas, assisting gas technicians and local emergency responders who are at the scene. Gas continuing to flow into the system can delay emergency response operations and place responders at risk of injury from an ongoing gas fire or secondary explosion. During the emergency response, the UGI mechanic followed company procedures for closing valves to isolate the natural gas system, working with UGI supervisors to determine which valves to close and other steps to isolate the system. As is typical during the response to an accident involving gas distribution systems, the UGI mechanic attempted to close the valves closest to the accident; these were all secondary valves. Pipeline operators often choose to close the valves closest to the leak to limit the impacted area and reduce the time it takes to burn off the remaining gas in the affected area. After the UGI mechanic closed the first valve about 5:30 p.m., he encountered difficulty locating the next valve necessary to shut off the rest of the gas flow. The mechanic found a valve with a gas cover in the area, but the valve itself had no plastic tag with a valve number. In July 2024, UGI excavated the site at the NTSB’s request and discovered that the correct gas valve had been paved over, and the mechanic had likely been looking at a nearby water valve. Because the UGI mechanic could not positively identify this valve as the correct one, he moved on to two other valves to fully isolate the system. The second of these valves (at South 4th Avenue and Penn Avenue) was not accessible until dirt and debris in the valve box was removed, so it was not closed until 6:15 p.m. Although this valve was designated as a secondary valve, it had been inspected by UGI about 12 months before the accident, and according to UGI’s records, the valve box was cleaned at that time. Nonetheless, dirt and debris had accumulated again and delayed isolation of the gas distribution system. The NTSB reviewed a 2018 image of South 2nd Avenue and Penn Avenue, in which a pair of water valves (valves A and B) are visible but not the gas valve, which was found to be paved over when UGI excavated the valve in 2024. UGI’s valve maintenance procedures include 5-year inspections for secondary valves, indicating that UGI would have attempted to inspect this valve while it was paved over, including its most recent documented inspection on March 23, 2021. However, there is no evidence that UGI was aware that the

Addressee Acronym: PA PUC

Addressee Organization Type: S-State Government

Communication Date: 2026-01-16

Communication Type: Staff-Level Communication

Communication Contents: Thank you for Chairman DeFrank’s letter dated January 9, 2026. We look forward to PAPUC’s next update, within 12 months or sooner when you have taken new substantive action to address the recommendation.

Addressee Acronym: PA PUC

Addressee Organization Type: S-State Government

Communication Date: 2025-07-07

Communication Type: Official Correspondence

Communication Contents: -From Stephen M. DeFrank, Chairman, Pennsylvania Public Utility Commission: By letter dated April 8, 2025, Chairman Homendy sent a letter requesting that the PAPUC respond within 90 days detailing the actions that the PAPUC has taken or intends to take to implement Safety Recommendation P-25-8. The PAPUC appreciates the opportunity to clarify how emergency valves are currently reviewed in Pennsylvania and explain additional steps it has taken to address the NTSB’s safety recommendation. The PAPUC has a team of 30 pipeline safety engineers who are in constant contact with jurisdictional natural gas pipeline operators. PAPUC safety engineers communicate with operators and conduct field visits regularly to ensure the continued provision of safe and reliable service. In addition to these ongoing efforts, the PAPUC’s safety engineers conduct Operation and Maintenance inspections of every jurisdictional pipeline operator at least once every five (5) years. This inspection includes a review of the utility’s designation and maintenance of emergency valves to ensure compliance with federal regulations. 49 CFR §§192.181, 192.747. Accordingly, the location and maintenance requirements of emergency valves are continuously reviewed by PAPUC’s safety engineers.

Addressee Acronym: PA PUC

Addressee Organization Type: S-State Government

Communication Date: 2026-01-09

Communication Type: Official Correspondence

Communication Contents: -From Stephen M. DeFrank, Chairman, Pennsylvania Public Utility Commission: The Pennsylvania Public Utility Commission (Commission or PAPUC) received your letter dated November 19, 2025 and appreciates the notification that the National Transportation Safety Board (NTSB) has classified the Commission's response to Safety Recommendation P-25-8 as an Open-Acceptable Response. The Commission continues to evaluate the methodology used by pipeline operators to determine the location of critical valves. We will assess corrective actions that may be implemented to consider the type of customer and emergency response time when designating emergency valves as directed in Safety Recommendation P-25-8. As requested, the PAPUC will advise you of additional actions to further implement the recommendation. Again, thank you for the notification of the NTSB 's classification of P-25-8 and the continued collaboration in support of this safety recommendation.

Addressee Acronym: PA PUC

Addressee Organization Type: S-State Government

Communication Date: 2025-11-19

Communication Type: Official Correspondence

Communication Contents: As part of our investigation, we reviewed the operator’s criteria for designating its critical valves and found that it considered the number of customers between emergency valves; however, the criteria made no reference to whether the operator also considered the type of customer or an estimate of the time required to isolate the system. Counting customers between valves alone may not accurately reflect who could be affected by a natural gas outage or emergency. We issued this recommendation to the PAPUC to assess the location of emergency valves using more stringent criteria than what is currently required. We understand that the PAPUC has issued a set of questions to jurisdictional pipelines to gather information on emergency valves and the methodologies used to interrupt service, and you are currently reviewing the submissions. We believe the questions align with Gas Piping Technology Committee guidance, and we would appreciate additional details on the criteria the PAPUC used to evaluate the placement of emergency valves. Pending the completion of your review and a summary of any corrective actions taken as a result, the Board has voted to classify Safety Recommendation P-25-8 OPEN—ACCEPTABLE RESPONSE.