Chemical Injection
NoDoC creates models for cost estimation of chemical injectio packages. Following describes the importance of corrosion inhibitors and the parameters that NoDoC considers for making models.
In spite of much advancement in the field of corrosion science and technology, the phenomenon of corrosion remains a major concern to industries around the world.
Ads by CinPlus-2.5c× Though the serious consequences of corrosion can be controlled to a great extent by selection of highly corrosion resistant materials, the cost factor associated with the same, favors the use of cheap metallic materials along with efficient corrosion prevention methods in many industrial applications. Utilization of corrosion inhibitors is currently the most common method of protecting against corrosion in all petrochemical facilities in the world. In this aspect, corrosion inhibitors have ample significance as individual inhibitors or as a component in chemical formulations. They have wide commercial applications such as in cooling waters, oil and gas fields, paints pigments, lubricants etc.
A large number of corrosion inhibitors have been developed and used for application to various systems depending on the medium treated, the type of surface that is susceptible to corrosion, the type of corrosion encountered, and the conditions to which the medium is exposed. The efficiency and usefulness of a corrosion inhibitor injection under one set of circumstances often does not imply the same for another set of circumstances. In many applications, a combination of more than one corrosion inhibitor along with other additives such as anti-scalents, biocides and polymeric dispersants are supplied. In spite of the long history of corrosion inhibition; a highly efficient and durable inhibitor that can completely protect iron and low carbon steel in aggressive environments such as high Cl- electrolyte for longer duration is yet to be realized.
CORROSION INHIBITOR
An inhibitor is a substance that, when added in small concentrations, decreases the effective corrosion rate. Inhibitors fall into four general categories based on mechanism and composition. These categories are
1- barrier layer formation
2- Neutralizing
3- Scavenging
4- Other environmental modification.
BARRIER INHIBITORS
Barrier layer formation inhibitors form a layer on the corroding metal surface, modifying the surface to reduce the apparent corrosion rate. They represent the largest class of inhibitive substances. Adsorption-type inhibitors are the most common barrier layer inhibitors. In general, these organic compounds are adsorbed and form a stable bond with the metal surface. The apparent corrosion rate decreases as surface adsorption is completed (Figure 2). VpCIs are adsorption-type inhibitors with high passivating properties. These inhibitors form a stable bond with the metallic surface. Generally, they have a high vapor pressure that allows the material to migrate to distant metallic surfaces. Therefore, VpCIs require no direct contact with the metal surface to be protected. Conversion inhibitors also form barrier layers. They passivate the metallic surface by developing an insoluble metal oxide on the surface. Typical examples of this type of inhibitor are organic phosphates and chromates.
NEUTRALIZING INHIBITORS
Neutralizing inhibitors reduce the hydrogen ion in the environment. Typical neutralizing inhibitors are amines, ammonia (NH3), and morpholine. These inhibitors are particularly effective in boiler WATER TREATMENT and weak acid solutions but have not been widely used on pipelines.
SCAVENGING INHIBITORS
Scavenging inhibitors remove corrosive ions from solutions. Well-known scavenging inhibitors include hydrazine and sodium sulfite. These two inhibitors remove dissolved oxygen from treated boiler water.
The successful selection of inhibitors depends on a clear understanding of the operation conditions, fluid properties, and flow conditions and it is essential that the worst case scenario prevailing in plant or pipeline is simulated in laboratory.
In spite of much advancement in the field of corrosion science and technology, the phenomenon of corrosion remains a major concern to industries around the world.
Ads by CinPlus-2.5c× Though the serious consequences of corrosion can be controlled to a great extent by selection of highly corrosion resistant materials, the cost factor associated with the same, favors the use of cheap metallic materials along with efficient corrosion prevention methods in many industrial applications. Utilization of corrosion inhibitors is currently the most common method of protecting against corrosion in all petrochemical facilities in the world. In this aspect, corrosion inhibitors have ample significance as individual inhibitors or as a component in chemical formulations. They have wide commercial applications such as in cooling waters, oil and gas fields, paints pigments, lubricants etc.
A large number of corrosion inhibitors have been developed and used for application to various systems depending on the medium treated, the type of surface that is susceptible to corrosion, the type of corrosion encountered, and the conditions to which the medium is exposed. The efficiency and usefulness of a corrosion inhibitor injection under one set of circumstances often does not imply the same for another set of circumstances. In many applications, a combination of more than one corrosion inhibitor along with other additives such as anti-scalents, biocides and polymeric dispersants are supplied. In spite of the long history of corrosion inhibition; a highly efficient and durable inhibitor that can completely protect iron and low carbon steel in aggressive environments such as high Cl- electrolyte for longer duration is yet to be realized.
CORROSION INHIBITOR
An inhibitor is a substance that, when added in small concentrations, decreases the effective corrosion rate. Inhibitors fall into four general categories based on mechanism and composition. These categories are
1- barrier layer formation
2- Neutralizing
3- Scavenging
4- Other environmental modification.
BARRIER INHIBITORS
Barrier layer formation inhibitors form a layer on the corroding metal surface, modifying the surface to reduce the apparent corrosion rate. They represent the largest class of inhibitive substances. Adsorption-type inhibitors are the most common barrier layer inhibitors. In general, these organic compounds are adsorbed and form a stable bond with the metal surface. The apparent corrosion rate decreases as surface adsorption is completed (Figure 2). VpCIs are adsorption-type inhibitors with high passivating properties. These inhibitors form a stable bond with the metallic surface. Generally, they have a high vapor pressure that allows the material to migrate to distant metallic surfaces. Therefore, VpCIs require no direct contact with the metal surface to be protected. Conversion inhibitors also form barrier layers. They passivate the metallic surface by developing an insoluble metal oxide on the surface. Typical examples of this type of inhibitor are organic phosphates and chromates.
NEUTRALIZING INHIBITORS
Neutralizing inhibitors reduce the hydrogen ion in the environment. Typical neutralizing inhibitors are amines, ammonia (NH3), and morpholine. These inhibitors are particularly effective in boiler WATER TREATMENT and weak acid solutions but have not been widely used on pipelines.
SCAVENGING INHIBITORS
Scavenging inhibitors remove corrosive ions from solutions. Well-known scavenging inhibitors include hydrazine and sodium sulfite. These two inhibitors remove dissolved oxygen from treated boiler water.
The successful selection of inhibitors depends on a clear understanding of the operation conditions, fluid properties, and flow conditions and it is essential that the worst case scenario prevailing in plant or pipeline is simulated in laboratory.
