Refine Non-Destructive Testing to Improve Nurse Tank Safety, Phase III

The objective of this project was to refine the non-destructive metallurgical testing method and protocol for detecting cracks in nurse tanks used to support guidelines (via a rulemaking) for when to require repair or order a nurse tank out-of-service, and to examine possible relationship of crack initiation and propagation to thickness of the steel used to fabricate the tank. Results are to support a National Transportation Safety Board (NTSB) recommended rulemaking by the Pipeline and Hazardous Materials Safety Administration (PHMSA) to address non-destructive testing of nurse tanks. Pressurized nurse tanks are used as the containers to provide the anhydrous ammonia for injection as a nitrogen fertilizer into the soil of fields for crops needing such a fertilizer. Tank failure reports indicate the greatest challenges to maintaining tank integrity are stress corrosion cracking (SCC) that tend to initiate around unannealed welds, and locally created high stress areas caused by tank damage incurred during service. An unknown number of tanks manufactured in the 1950s through the 1970s that are still in use today were manufactured with higher strength steel, which is more prone to SCC. Then, beginning in 1999 with the new American Society of Mechanical Engineers (ASME) standards, nurse tanks started being manufactured with thinner steel (in which the welds are not annealed to relieve the very high residual stresses in the welded joints where SCCs could initiate and then propagate), and more recently manufacturers have begun using the thinnest possible steel stock (meeting the ASME thickness requirement), which when fabricated has locations that do not meet the minimum thickness requirement.


  • Status: Completed
  • Sponsor Organizations:

    Federal Motor Carrier Safety Administration

    1200 New Jersey Avenue, SE
    Washington, DC  United States  20590
  • Managing Organizations:

    Federal Motor Carrier Safety Administration

    1200 New Jersey Avenue, SE
    Washington, DC  United States  20590
  • Project Managers:

    Goettee, David

  • Performing Organizations:

    Maineway Services

    10 Tamarack Drive
    Fryeburg, ME  United States  04037

    Iowa State University, Ames

    Center for Transportation Research and Education
    2711 South Loop Drive, Suite 4700
    Ames, IA  United States  50010-8664
  • Start Date: 20130000
  • Expected Completion Date: 20151230
  • Actual Completion Date: 0

Subject/Index Terms

Filing Info

  • Accession Number: 01592627
  • Record Type: Research project
  • Source Agency: Federal Motor Carrier Safety Administration
  • Files: RiP, USDOT
  • Created Date: Mar 3 2016 3:34PM