Testing and Recommended Practices to Improve Nurse Tank Safety, Phase I [Research Brief]

https://doi.org/10.21949/15027902013PDFBriefTanks (Containers)SteelStress crackingResidual stressMetallographySpectroscopyInspectionCase studiesHazardous materialsLiterature reviewsUnited StatesUnited States. Department of Transportation. Federal Motor Carrier Safety Administration. Office of Analysis, Research, and TechnologyUnited States. Department of Transportation. Federal Motor Carrier Safety Administration. Office of Analysis, Research, and TechnologyUnited States Federal Motor Carrier Safety AdministrationThis study focuses on determining causes and possible inspection remediation strategies to reduce the occurrence of anhydrous ammonia (NH3) nurse tank failures. Nurse tanks are cylindrical steel tank shells with hemispherical or elliptical end caps referred to as heads, designed to hold NH3 in liquid form under pressure (see Figure 1). Widely used as an agricultural nitrogen-rich fertilizer, NH3 is a caustic substance that requires great care when handling. A variety of metallurgical tests were performed on 20 used nurse tanks and on laboratory specimens cut from these tanks. Testing corroborated the conclusion from other studies that stress corrosion cracking (SCC) is the principal threat to nurse tank integrity, although manufacturing defects and damage from operations are also possible issues.84