Circumferential Catastrophic Burst Failures of Pressurized Cylinders

Abstract

Complete circumferential (360°) tearing has been observed at the bottom of body walls in a number of three-piece, steel, cylindrical aerosol containers. This type of failure has not been well documented and analyzed in previous aerosol can failure analysis literature. In one instance, a worker accidentally dropped an aerosol spray paint can, and it instantly burst via catastrophic 360° circumferential failure near the bottom of the body wall. This was a relatively low-pressure, low-temperature, nearly instantaneous fracture. The burst aerosol became a high-velocity rocket and impacted the worker in the face and caused the loss of one eye. Other similar incidents involving this same failure mechanism have occurred with varying degrees of injury. The objective of this study was to determine why the aerosols catastrophically burst in the 360° circumferential manner and, more importantly, to find a remedy and prevent future failures. Test methods were developed to quantitatively control the force and angle of impact that might result from the tapping, hitting, or accidental dropping of an aerosol container. More common failure analysis methods were also used, such as metallography, scanning electron microscopy, energy dispersive spectroscopy, simple bending tests to simulate low-cycle fatigue, and a method to measure internal aerosol pressure as a function of temperature. The most likely root cause for the 360° burst failures was determined to be a combination of pre-existing circumferential flaw or flaws, the anisotropic microstructure of the aerosol body steel and above yield stress that is facilitated by the geometry of the body-to-bottom design when the aerosol is tapped, hit, or accidentally dropped. Experiments show that changing microstructure and/or design significantly reduce the likelihood of this failure mechanism and offer simple, cost-effective remedies.