A corroded steam pipe that the gas operator did not know about. A 1982 plastic service tee beside it. Seven people killed.
What happened
On 24 March 2023 a natural gas explosion at a candy factory in West Reading, Pennsylvania, killed seven people, injured ten and destroyed one building. The US National Transportation Safety Board (NTSB) investigated.
What the investigators found
The NTSB found that a retired 1982 Aldyl A polyethylene service tee with a Delrin polyacetal insert had degraded. The ground around it had been heated by a corroded underground steam pipe, and elevated ground temperature can increase crack growth in susceptible plastic piping materials.
In January 2026 the Pipeline and Hazardous Materials Safety Administration (PHMSA) issued Advisory Bulletin ADB-2026-01. It asks gas distribution operators to account for sources of elevated temperature in their integrity management plans. The susceptible materials it lists include plastic pipe installed between 1960 and the early 1980s, low-ductility Aldyl A pipe made before 1973, PE 3306 pipe, and Aldyl A tees with Delrin inserts. Recommended measures include leak management, pipe replacement or remediation, checking material type during routine work, and extra leak surveys.
What it means for asset owners
Materials selection is not only a metals question. Polymers have temperature and environment limits, and they age. The threat here also came from a neighbouring asset the gas operator did not own, so a risk assessment is only as good as its knowledge of what lies around the pipe.
What an engineer should check
- Do you hold an inventory of legacy plastic pipe and fittings, by material and installation date?
- Are heat sources near plastic assets (steam lines, hot process lines, buried services) identified and recorded?
- When plastic pipe is specified near heat, is its long-term temperature rating checked against the real ground or ambient temperature?
Source. J. E. Hainline and S. A. Olenchuk (Van Ness Feldman LLP), "PHMSA Issues Advisory Bulletin to Owners and Operators of Natural Gas Distribution Systems with Plastic Piping and Components in Wake of Deadly Candy Factory Explosion", National Law Review, 23 January 2026. Read the original article. Original documents: PHMSA Advisory Bulletin ADB-2026-01; NTSB report NTSB/PIR-25/01. This article summarises the source in our own words; see the original for full details. It is general technical information, not advice on a specific asset.
Related reading
- Materials selection for corrosive environments
- What to preserve after a component fails
- MTIS materials selection services
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