Harvey Rice, PMC Global Industries Inc.
As the cost of maintenance of gas transmission lines and plant maintenance at gas gathering sites has increased, the detection and control of 02, H2S, and CO, has become an important issue in cost controls and safety. Even though the actual costs related to the presence of these elements isn"t known exactly, the cost per location is estimated to be in the millions of dollars annually. The corrosion-related cost to the transmission pipeline industries is estimated to be between $5 billion and $8 billion annually. Obviously, all of these costs can"t be attributed to of 02, H2S, and CO,, but these three elements are a large contributing factor to these costs. In some gas high levels of CO, is present; therefore the removal of this element to meet the 4% contractual requirement is necessary thus contributing to the cost. In addition, CO, is an acid gas that contributes to the corrosion problem. The safety of transmission lines has a far-reaching affect including life, property damage, and large monetary liabilities for the transmission companies involved. Early detection and preventing the corrosion of these transmission lines, which in turn, prevents pipeline explosions, is extremely important. These elements accelerate the corrosion on all carbon steel components including the pipeline systems and components in plants. It is true that most of the carbon steel systems are protected with corrosion inhibitors, but large quantities of oxygen cause the inhibitors to have a limited amount of protection. It has been determined that oxygen levels of 10 PPM or less will have very little affect on these inhibitors. The identification of sources of oxygen and the recognition of hydrogen sulfide and carbon dioxide present in natural gas has become very important to corrosion prevention programs. The cost of this identification and elimination of the sources is far less than the cost of the repair and the liabilities of the corrosive affects if left unattended.