The Canadian Association of Agri-Retailers is perplexed about Transport Canada leaving the NH3 industry without access to new tanks and forcing more frequent pressure tests.
Increasing the frequency of hydrostatic pressure tests from five years to three years will increase the risk of tank failures, according to CAAR. Numerous studies have shown that the introduction of oxygen into anhydrous tanks accelerates stress corrosion cracking. CAAR says more open tank tests will result in more premature tank failures.
Under the pre-2012 changes, Canadian tanks had a pass rate more than 99 percent in the hydrostatic tests on the five-year cycle. Tanks that have been operating since the 1970s are tested every five years and continue to pass.
There’s a strong likelihood the pass rate will decline when tanks go to three-year hydrostatic cycles, says CAAR.
Ammonia tanks themselves do not present a major hazard, according to data from CAAR members and Transport Canada.
“The more we dig into the data, the more we see the industry perception that anhydrous tanks are safe is a correct perception. The system we’ve had for years is working at catching bad equipment,” says CAAR chief executive officer Delaney Ross Burtnack.
“One of the things we’ve uncovered going through this data is a continuous improvement in safety, based on nurse tank incident reports to Transport Canada. According to their own data, there hasn’t been a pinhole leak reported in the field since 2009. There was one pinhole leak detected during (visual) inspection in 2012, but that’s what the inspection is for.
“Less than six percent of all reports from 2004 to 2014 related to pinholes, and none of those were a crisis. The last time we had an actual injury was 2015, and that wasn’t a tank issue. Nearly all human safety incidents are hose and valve issues, not tank issues. That’s where Transport Canada and the industry should focus their attention.”