FMCSA-PHMSA Publishes Nurse-Tank Safety Advisory

Earlier this month, DOT Federal Motor Carrier Safety Administration (FMCSA) and Pipeline and Hazardous Materials Safety Administration (PHMSA) published a Safety Advisory for “Possible Catastrophic Failure of Nurse Tanks and Recommendation for Periodic Testing”. The two agencies are recommending that owners of Anhydrous Ammonia Nurse Tanks manufactured by American Welding & Tank (AWT) between 2007 and 2011 “conduct voluntary periodic visual inspection in accordance with 49 CFR §173.315(m)(2)(i); thickness testing in accordance with 49 CFR §173.315(m)(2)(ii), and pressure testing in accordance with 49 CFR §173.315(m)(2)(iii).”

Generally speaking, anhydrous ammonia nurse tanks, that are considered an implement of husbandry transporting anhydrous ammonia and operated by a private motor carrier exclusively for agricultural purposes are exempted from periodic inspection requirements as long as the tank is marked with a valid, and legible ASME plate. For the purposes of this advisory, however, FMCSA and PHMSA are recommending periodic (every five years) voluntary testing in accordance with §173.315(m)(2)(iv).

According to the Safety Advisory:

“On August 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 product. 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 that were manufactured between 2008 and 2012. Radiographic testing showed that 7 of 8 the 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.1 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.”

The advisory also reports that:

“This notice focuses on nurse tanks manufactured from January 1, 2007, through December 31, 2011, by American Welding and Tank (AWT) at its Fremont, Ohio plant. 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.” (FMCSA press release here; AWT press release here)