Rupture Explosion Failure Analysis Of CO₂ Steel Cylinder

CO₂ is widely used in petrochemical industry,food,welding,fire control,refrigeration,medical,agricultural and oil exploration and other fields.CO₂ Cylinders are very commonly used in place of factory,laboratory,commercial area,residential area,etc.Bottled CO₂ is generally in form of high-pressure liquefied gas.The improper management or the existence of defects in the cylinder may lead to cylinder failure and even accidents.The failure of cylinder filling high-pressure CO₂ may bring serious damages and injuries.Cylinder with hidden defects is like a bomb placed around people which may bring great threat to life and property of the citizens.A 37 Mn steel CO₂ cylinder failed and caused an explosion accident that occurred in a gas filling company.This paper presents analysis on the exploded cylinder to find out the cause of the failure,therefore to provide technical and protection measures for the production,use and management of CO₂ cylinders.Through the observation into the damaged cylinder at explosion scene and macro analysis the cylinder rupture characteristics.Preliminary analysis of the causes of the explosion.Further investigation into the various factors leading to the initial cracks in the inner wall of the cylinder causes of cylinder and explosion are also conducted through determination of wall thickness,material chemical composition analysis,mechanical property test,metallographic analysis,SEM morphology and spectrum analysis,XRD phase analysis.Through calculation,analysis the stress of the body in different operation pressure,simulation with ANSYS software were used to analyze the longitudinal crack and transverse cracks are existed in the cylinder body and under different load local stress concentration.Through stress corrosion test of 37 Mn cylinder sample in saturated sodium carbonate solution to verify the stress corrosion of the samples in CO₃^2--HCO₃^-medium saturated sodium carbonate solution.It is founded that root causes of the physical rupture and cylinder explosion are due to internal stress corrosion cracking of the steel cylinder under internal pressure together with the vibration of the transport process and lack of capacity to withstand the pressure of the cylinder.