Failure Analysis on Bulge of Tube Trailer Gas Cylinders

By means of chemical compositions analysis, room temperature tensile test and low temperature impact test, Brinell hardness test and metallographic examination, the bulge causes of tube trailer gas cylinders were analyzed. The results show that bulge of the cylinders was caused by the improper heat treatment which resulted in abnormal microstructure with more ferrite and reduced the strength and hardness of the cylinder. When the local working pressure exceeded the yield strength of the cylinder, bulge phenomenon would happen.