EFFECT OF TEMPERATURE ON FAILURE OF GAS-CYLINDERS

A number of ammonia cylinders burst during open storage in a field in the month of June. The cause of failure was studied. No flaws in the c ylinder material were detected. Under normal conditions, the tangentia l stress (5.4 kg/mm(2)) in the cylinder is well below the yield streng th (49 kg/mm(2)). The tangential stress increases with the rise of tem perature of the ammonia. As long as some vapor exists inside the cylin der, the liquid remains in equilibrium with the vapor, the cylinder pr essure is equal to the vapor pressure of ammonia at that temperature, and the rise in tangential stress is insignificant (0.14 kg/mm(2)/degr ees C). However, as the temperature increases, the specific volume of the liquid ammonia inside the cylinder also increases. The cylinder is completely filled with liquid under certain conditions in accordance with the bulk thermal expansion of the liquid; under these conditions, the cylinder pressure rises sharply with increased temperature, causi ng a large rise in tangential stress (4.76 kg/mm(2)/degrees C). Thus, an approximate 10 degrees C temperature rise in a cylinder filled with liquid ammonia can lead to failure.