# NTSB Safety Recommendation P-25-017

- **operation:** document
- **citation:** P-25-017
- **title:** NTSB Safety Recommendation P-25-017
- **source type:** guidance
- **agency:** National Transportation Safety Board
- **status:** guidance
- **official:** true
- **published on:** 2025-04-08
- **effective on:** 2025-04-08
- **summary:** TO UGI CORPORATION: Inventory all your plastic natural gas assets that may be located in elevated temperature environments and address the risk associated with these assets.
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- **app url:** https://regulus.evalyn.ai/document/ntsb-recommendation-p-25-017
- **source url:** https://data.ntsb.gov/carol-main-public/sr-details/P-25-017
**body:**

NTSB safety recommendation P-25-017.

TO UGI CORPORATION: Inventory all your plastic natural gas assets that may be located in elevated temperature environments and address the risk associated with these assets.

Priority: CLASS II

Overall Status: Open - Initial Response Received

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: UGI Corporation

Addressee Status: Open - Initial Response Received

Addressee Organization Type: P-Private Industry

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 UGI Corporation 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 UGI Corporation (additional information regarding this recommendation can be found in the noted section of the report): • Inventory all your plastic natural gas assets that may be located in elevated temperature environments and address the risk associated with these assets. (P-25-17) (See section 2.3.) 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-25-17). 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 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-25-17). 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: 2.3 Insufficient Consideration of Known Threats from Plastic Piping The vulnerability to slow crack growth, also called brittle-like cracking, of early vintage Aldyl A and other early vintage polyethylene piping materials under certain environmental (such as high ground temperatures), installation, and service conditions has been extensively documented. In 1998, the NTSB issued a special investigation report, Brittle-Like Cracking in Plastic Pipe for Gas Service, which concluded that the procedure used in the United States to rate the strength of plastic pipe may have overrated the strength and resistance to brittle-like cracking of much of the plastic pipe manufactured and used for gas service from the 1960s through the early 1980s. The report found that much of this early vintage plastic piping may therefore be susceptible to premature brittle-like cracking failures when subjected to stress intensification (NTSB 1998). In response, PHMSA and its predecessor, the Research and Special Programs Administration, issued four advisory bulletins addressing brittle-like cracking in plastic pipe materials. The 2002 bulletin Notification of the Susceptibility to Premature Brittle-Like Cracking of Older Plastic Pipe warned that “brittle-like cracking (also known as slow crack growth) can substantially reduce the service life of polyethylene piping systems” (Research and Special Programs Administration 2002). The bulletin specifically cited certain Aldyl A piping material manufactured by DuPont Company before 1973—the same material as the retired Building 2 service tee—as potentially susceptible to brittle-like cracking. A 2007 update to the advisory bulletin added Delrin-insert tapping tees to the list of polyethylene pipe materials susceptible to brittle-like cracking. District heating systems that use underground steam pipes like the one used by Palmer can be found throughout the United States, particularly in large cities like New York; San Francisco, California; Philadelphia, Pennsylvania; and Denver, Colorado. Of the 68 district heating systems still operating, just over half were built before 1950—with one quarter built before 1900 (Pierce 2022). The extent of district heating systems nationwide means that other natural gas pipeline operators may have assets near steam pipes. Research has established that elevated temperatures can affect the pressure rating of polyethylene plastic piping, with one study citing the adverse effects of district heating systems on polyethylene gas pipelines (Akhmerova and others 2021). Early vintage Aldyl A piping is limited to operating conditions below 100°F, and operating outside these conditions increases the risk of slow crack growth. For plastic piping in general, the ri

Addressee Organization Type: P-Private Industry

Communication Date: 2025-07-05

Communication Type: Official Correspondence

Communication Contents: -From Hans G. Bell, President, UGI Utilities, Inc., UGI Utilities is a wholly owned subsidiary of UGI Corporation: UGI Corporation (UGI) submits this letter and attachments in response to the above-referenced NTSB recommendation and the letter issued by the National Transportation Safety Board (NTSB) on April 8, 2025, concerning the NTSB’s March 18, 2025, Report, UGI Corporation Natural Gas-Fueled Explosion and Fire, West Reading, Pennsylvania, March 24, 2023. As further detailed in the enclosed response to this letter (Attachment 1), UGI has either already, or will soon be, fully implementing the NTSB’s recommendation P-25-17. UGI recognizes the critical role of the NTSB to investigate transportation accidents to determine probable causes and make recommendations to mitigate the likelihood of recurrence. As such, we appreciate the significant effort the NTSB has made while investigating the incident at West Reading. UGI and the NTSB share a mutual goal to ensure the safe operation of pipelines. To this end, UGI has been transparent with and responsive to the NTSB, while serving as a cooperative and integral member of the investigation team. The primary objective throughout the investigation has been to identify the root cause of the incident and possible contributing factors so that UGI, and other operators, can implement appropriate measures to prevent reoccurrence and to continually improve the safety of natural gas pipeline operations. From the outset, UGI has taken every opportunity to learn from this incident and apply enhancements to its system, processes, procedures, and organizational structure, immediately and throughout the investigative process. UGI will continue to utilize its leadership position in the natural gas utility industry to share learnings and promote safety enhancements. UGI prides itself on having a culture that is focused on its values of safety, integrity, respect, and inclusion in support of our communities, the environment, and each other. UGI’s employees take great pride in their work as well as full responsibility and accountability for actions when things go wrong. UGI believes that the Company’s actions following the West Reading incident align with these values. UGI’s highest priority is operating its assets safely and reliably to protect people, communities, and the environment. UGI believes that continuous improvement is essential to its safety culture. Toward that end, UGI will continue to implement actions and system enhancements to manage risks and prevent incidents across the lifecycle of its assets. UGI will remain diligent and determined in this regard. Please do not hesitate to contact me if you have any concerns. UGI Corporation Response to NTSB Recommendation UGI Corporation (UGI) holds its commitment to safety as a core value and takes seriously its efforts to continually improve safety and reliability performance. Since the West Reading incident on March 24, 2023, UGI has implemented measures to mitigate and avoid a similar incident. These measures include: • Implementation of probabilistic risk modeling tools that normalize risk outputs across a granular set of asset types (transmission pipe, distribution pipe, services, regulator stations, etc.). Transmission model completed in September 2024; distribution model is on track and scheduled to be deployed by December 2025. • Completed a review of Aldyl-A assets and asset records and created a definition of a vintage plastic asset population comprised of plastic pipe and fittings historically installed at UGI and its predecessor companies. • Initiated procedural changes to prescribe the remediation of Aldyl-A tapping tees with Delrin inserts upon excavation. • Enhanced field procedures and data collection, including the deployment of GPS-enabled field tools, to significantly improve asset records and surveillance of vintage plastic assets, including enhanced material failure reporting. • Enhanced field procedures, improving surveillance for steam facilities. • Created a new safety campaign, “Smell Gas, Act Fast” including digital billboard signage, a website safety-page refresh, and social media advertising. Campaign materials were further leveraged through the development of UGI Safety Kits for commercial and industrial Customers and their employees. Deployment included a pilot of face-to-face meetings with over 100 commercial and industrial customers to provide UGI Safety Kits. Additionally, over 70,000 commercial and industrial customers received a brochure containing information similar to the UGI Safety Kits, including directions to contact UGI to order free safety-related materials such as signage, magnets, and scratch and sniff cards. • UGI is currently participating with GTI Energy through their Operations Technology Development collaborative effort with other natural gas utilities to pilot and test methane detectors utilizing LTE-M technology. Based on the results of this one-year pilot, UGI will consider whether this technology may be incorporated in certain scenarios. Concurrently, UGI completed a review of commercially available methane detectors/alarms and has committed to implementing a two-year, minimum 500-methane-detector pilot program within its service territory, beginning in the fourth calendar quarter of 2025. • Updated valve installation and inspection procedures requiring the installation of an additional location device, a marker ball, whenever an existing valve is exposed during field activities. The presence of a marker ball will provide field personnel with additional means to confirm the location of a gas valve. Additionally, the modified procedures now require field employees to confirm and record that the valve identification number observed in the field matches the digital valve record when performing an inspection. If a discrepancy is found, a new process will generate a follow-up work order for field employees to resolve the issue. Below is UGI’s response to the specific NTSB recommendation directed at UGI. UGI Response: UGI agrees with NTSB Recommendation P-25-17. Prior to the National Transportation Safety Board’s Final Report on this matter and subsequent recommendation to UGI, UGI began to proactively inventory its plastic assets located in high temperature environments by contacting a subset of customers to identify the potential for gas asset proximity to below-ground steam lines. UGI identified and contacted 34 customers comprising of various industry types that may operate underground steam systems. A combination of Engineering, Operations, and Customer Development personnel communicated with each UGI customer to ascertain whether a below-ground steam system was operating on each premise. The locations of reported steam pipelines were compared to the location of UGI assets utilizing GIS records, paper and electronic sketches, and information obtained through on-site field reviews. Using this approach, UGI concluded that 20 of the 34 customer locations do not have a conflict between UGI assets and below-ground steam facilities, while 14 customer locations required further investigation and potential remediation. UGI also initiated a monthly leak survey at all 14 locations until final remediation is performed. UGI’s Distribution Integrity Management Program (DIMP) department oversaw the efforts summarized above and created an index-based risk model to aid in the prioritization of each customer location with potential conflicts between UGI facilities and underground customer-owned steam lines. Within this model, UGI prioritized the canvassing and remediation of five customer locations where vintage plastic conflicts were identified. UGI has expedited the remediation of all five locations, with four of the five complete as of June 30, 2025. Remediation efforts continue at the final location involving vintage plastic, wi
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