FMCSA: Nurse Tank Safety Advisory
Safety Agencies Issue Anhydrous Ammonia Nurse Tank Advisory
OMAHA (DTN) -- A safety advisory was issued by the Federal Motor Carrier Safety Administration (FMCSA) and the Pipeline and Hazardous Materials Safety Administration (PHMSA) about the possibility of catastrophic failure of certain hazardous materials containers known as nurse tanks.
The advisory focuses on nurse tanks manufactured from Jan. 1, 2007, through December 31, 2011, by American Welding and Tank (AWT) at its plant in Fremont, Ohio, according to a FMSCA press release. Nurse tanks manufactured by AWT from 2009 to 2010 were the subject of a prior FMCSA investigation and enforcement action in response to improper manufacturing procedures.
On Aug. 23, 2023, a 2009 AWT nurse tank containing anhydrous ammonia experienced a catastrophic failure in a farm co-op lot, resulting in the release of all its contents. The failure caused the tank shell to "rocket" over 300 feet from its original location.
While no injuries were reported, this event is an indicator of potential continuing problems with AWT nurse tanks that have now been in service for over a decade. As a result of this incident, the owner of the nurse tank involved contracted with a third-party testing company to examine their AWT nurse tanks which were manufactured between 2008 and 2012.
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Radiographic testing showed that seven of eight nurse tanks tested had extreme stress corrosion cracking, porosity, and inclusions/voids in the welds where the heads and shells of the nurse tanks were joined. Only the 2012 tank passed.
The nurse tank owner submitted these results to engineering experts who were involved in previous research funded by FMCSA into similar issues with this series of AWT nurse tanks. Based on the test results and the review by the experts, the owner voluntarily placed the nurse tanks out of service.
The parent company of the farm co-op subsequently conducted similar radiographic testing on 142 AWT nurse tanks manufactured between 2007 and 2012, and 100 failed the test. All 2012 tanks passed.
According to the FMCSA, the current Hazardous Materials Regulations do not require periodic inspection and testing of nurse tanks that have attached and legible American Society of Mechanical Engineers (ASME) identification plates. Requirements for periodic inspection and testing of nurse tanks apply only when the ASME plate is missing or illegible.
The FMCSA and PHMSA nevertheless strongly recommend owners of AWT nurse tanks manufactured between Jan. 1, 2007, and Dec. 31, 2011, that are exempted from periodic inspection and testing requirements conduct voluntary periodic visual inspection. Note these dates reflect the years of manufacture that failed testing.
For owners of affected AWT nurse tanks unable to conduct voluntary pressure testing, FMCSA and PHMSA recommend either radiographic or ultrasonic testing be conducted. While the period of voluntary inspection and testing is at the discretion of the nurse tank owner, FMCSA and PHMSA recommend conducting the inspection and testing at least once every five years consistent with federal regulations.
Russ Quinn can be reached at Russ.Quinn@dtn.com
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