HOW TO PRESSURIZE AUTOCLAVES FOR CORROSION TESTING UNDER CO_2 AND H_2S PRESSURE

摘要

All the methods presently used for pressurizing autoclaves have their advantages and disadvantages. Pressurizing with pure gases is undoubtedly the surest method, since it is insensitive to the autoclave filling rate, and the influence of temperature stability can be readily controlled. The only limitation is the impossibility of accurately reproducing very low H_2S partial pressures (< 30 mbar) at high temperatures (> 150℃). Conventional pressurizing with gas mixtures is not at all practical, since it demands either excessively large autoclaves or the bubbling of prohibitive volumes of gas.In order to overcome these fundamental difficulties, alternative methods are proposed, such as high temperature bubbling using a cooled reflux condenser, or presaturation of the autoclave at 60℃ at a fraction of the test pressure, enabling the latter to be attained during subsequent heating by the natural increase in pressure with temperature.