Brian Downie, who handles the regulatory side of Shur-Gro’s anhydrous ammonia operations, says he feels comfortable standing next to any nurse tank currently in service in Canada.
The ag industry weeded out problem tanks when more robust testing was implemented about a decade ago, he said. Today, he’s confident in the required regimen.
“They’re tested so stringently that they’re really, really safe now,” he said.
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Why it matters: Anhydrous ammonia has many advantages, but it’s dangerous to work with and so are its storage tanks if not carefully maintained.
In February, U.S. officials issued a warning that a certain age and make of nurse tanks were at risk of catastrophic failure.
The advisory stemmed from an August 2023 incident at a farm co-op, in which a tank manufactured in 2009 by American Welding and Tank (AWT) failed. The release of stored anhydrous ammonia caused it to “rocket” 300 metres.
“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,” said a release from the U.S. Federal Motor Carrier Safety Administration.
The company was subject to an earlier FMCSA investigation for models manufactured in 2009 and 2010. That resulted in “enforcement action in response to improper manufacturing procedures,” the agency said.
After having one tank shoot across their lot, the tank’s owners pursued testing on their other AWT tanks manufactured from 2008-12. Only one, manufactured in 2012, passed radiographic testing.
Seven of the eight “had extreme stress corrosion cracking, porosity, and inclusions/voids in the welds where the heads and shells of the nurse tanks were joined,” according to the FMCSA.
The tank owner took those tanks out of service and ordered broader follow up testing of their fleet. Those tests evaluated 142 AWT tanks manufactured between 2007 and 2012. All 2012 tanks passed, but 100 older tanks did not.
The FMCSA and U.S. Pipeline and Hazardous Materials Safety Administration is now advising anyone with an AWT nurse tank manufactured between Jan. 1, 2007, and Dec. 31, 2011, to get those tanks tested.
The release was noted March 4 by the Canadian Association of Agri-Retailers. Canadian officials are checking whether any of the noted tanks were sold in Canada, CAAR said.
Fertilizer Canada said it is aware of the safety notice and a recommendation that 2009 and 2010 tanks be tested.
“At this time, Fertilizer Canada is not aware of any of these nurse tanks in the Canadian market,” a spokesperson said via email. The association also said it is working to make retailers aware of the situation and remind them of regulatory requirements.
Downie doesn’t know of any tanks subject to the safety notice on Shur-Gro’s lots, but “we’re certainly going to do an in-depth audit and make sure that there isn’t any here.”
Testing requirements
In Canada, retailers dealing in anhydrous ammonia have guidelines for inspections and testing under the Transportation of Dangerous Goods Regulations and CSA B620 Standard, Fertilizer Canada noted. Likewise, “all Canadian ammonia agri-retailers are required to maintain compliance with Fertilizer Canada’s Ammonia Code of Practice, which references the regulatory requirements and adds industry best practices.”
That code includes third-party audits every two years.
“They audit our wagons and they audit our site and all the paraphernalia that goes along with anhydrous,” said Downie, adding that no retailer gets anhydrous shipped to them unless certified to be in compliance with the Ammonia Code of Practice.
As well as mandated audits, there are random audits by Transport Canada. Tanks also undergo a hydro test every three to five years.
“Anhydrous is pumped out of these wagons; we fill the wagons full of water and they are pressure tested up past their rating holding capacity,” Downie said. “We have to hold that test without leakage for a given amount of time.”
Transport Canada also mandates an annual leakage test.
“Every year we do a visual (inspection) and a leakage test and a hose test on every wagon or tank,” Downie said. “So, on a yearly basis, they probably get in the neighbourhood of two hours of testing each year.”
The hydro test adds another hour and a half of testing during the years it’s required, he noted.
On the farm
For farmers with their own nurse tanks, Fertilizer Canada stressed the need to inspect those tanks daily during application season, as well as before and after each use.
According to an emailed checklist sent to the Co-operator, those inspections should:
- Make sure the hitch bolts are in good condition and tight.
- nspect hitch welds for stress cracks.
- Ensure the drawbar tongue is in good shape and that the hitch pin hole is in good condition.
- Check for the presence and condition of the chains.
- Inspect the hose routing and securement.
- Check the mounting of pedestal bolts that secured the tank to the wagon.
- Check springs to ensure there are no broken leaves.
- Inspect welds holding spindles to the frame for cracking.
- Inspect nurse wagon tires for wear and ensure lug nuts are present and tight.
- Inspect the nurse wagon for stress cracks in the frame.
Also, Fertilizer Canada said, “annual nurse tank maintenance should include paint, decal, and marking maintenance or replacement, valve inspection or replacement, hose testing, and tank inspection and periodic testing.”
