A method of forming a cell is to connect two electrodes of the same metal while they are submerged in electrolytes that contain different substances or the same substance in different concentrations. 5 Differences in salt concentration along a pipeline can cause one section of the pipeline to become anodic in comparison to another section of the pipeline. Anomalies such as anodic sites will typically develop in higher salt concentrations, unless the higher salt concentration is that of a metal salt (not typical in pipelines). It is estimated that up to 90% of corrosion in soils and natural waters is caused by oxygen and concentration cells formed by the accumulation of salts.
Oxygen concentration cells are responsible for a large number of corrosion problems on pipelines. Areas with high oxygen concentrations are referred to as cathodes, while areas with low oxygen concentrations are referred to as anodic areas. There are numerous locations along a pipeline where concentration cells can be found, including:
- Ditches with loose soil around the pipe, such as those were the pipe rests on the bottom of a ditch, will allow for more oxygen to be absorbed by the pipe’s top and sides. This will result in a low oxygen concentration at the bottom of the pipe, which becomes the anode
- There will be a difference in oxygen concentration where pipelines pass beneath a road, slab, or other structure. The area immediately beneath the road will have a lower concentration of oxygen (and thus will act as an anode) than the adjacent area immediately outside the edge of the road, where oxygen is more readily available (and thus will not act as an anode). However, because oxygen can easily penetrate the soil just outside the road’s edge, the corrosion just beneath the road’s edge can be accelerated. The natural process is for the excess of oxygen to be reduced in order to bring both sides’ concentrations to the same level. Prior to the use of good coatings and CP, this was a major corrosion problem for pipelines, and it is one of the reasons that road casings have become increasingly popular.
- Where the pipe enters the ground or the water, the concentration of oxygen can be a significant issue for the environment. Because there is a significant difference in the concentration level at the soil surface compared to the concentration level just below the soil surface, the anodic area will be located just below the soil surface. The same principle will apply where the pipe enters or exits water environments where wave action results in a higher concentration of oxygen just above the water line than just below the surface of the water.
Effects of 40 percent oxygen
This study examined the acute effects of 40% oxygen supplementation in adults with cyanotic congenital heart disease (CCHD). These young patients have significant morbidity and premature mortality, relating in part to their cyanotic state. We have shown that systemic arterial oxygen saturation (SAOS) increases significantly when these patients are administered 40% oxygen, irrespective of their underlying congenital cardiovascular diagnosis or the presence of pulmonary hypertension. Forty per cent oxygen supplementation increased SAOS above 85% in the majority of patients, with none having an SAOS less than 80%. This improvement in saturation may be clinically important because significant erythrocytosis is unusual if SAOS is greater than 85% and it is this physiological adaptation which is responsible for many of the symptoms experienced by these patients.
Using adults with cyanotic congenital heart disease as subjects, this study investigated the acute effects of 40 percent oxygen supplementation (CCHD). A significant amount of morbidity and premature mortality occurs in these young patients, which can be attributed in part to their cyanotic state. We have demonstrated that when these patients are given 40 percent oxygen, their systemic arterial oxygen saturation (SAOS) increases significantly, regardless of their underlying congenital cardiovascular diagnosis or the presence of pulmonary hypertension. The majority of patients had a SAOS greater than 85 percent after receiving 40% oxygen supplementation, with none having a SAOS less than 80 percent. Significant erythrocytosis is uncommon when SAOS is greater than 85 percent, and it is this physiological adaptation that is responsible for many of the symptoms experienced by these patients. Therefore, this improvement in saturation may be clinically significant.
Conclusion
The fraction of oxygen dissolved in or carried by a fluid is referred to as oxygen saturation.
A method of forming a cell is to connect two electrodes of the same metal while they are submerged in electrolytes that contain different substances or the same substance in different concentrations.It is estimated that up to 90% of corrosion in soils and natural waters is caused by oxygen and concentration cells formed by the accumulation of salts.
The acute effects of 40% oxygen supplementation in adults with cyanotic congenital heart disease (CCHD).Using adults with cyanotic congenital heart disease as subjects, this study investigated the acute effects of 40 percent oxygen supplementation (CCHD).