Factors affecting corrosion
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I work in corrosion monitoring, primarily using the weight loss method on test pieces and the probe method to measure the corrosion rate of fluids inside pipelines in the field. Based on the monitoring results obtained multiple times within a year (samples were taken every two months for analysis), the corrosion rate each time was slightly lower, ranging from 0.0010 to 0.0100 mm/a; it was sometimes higher and sometimes lower, with significant variations. What causes such large differences? Medium? Temperature? I would appreciate the guidance from all experts. Thank you!
There are many factors. In addition to differences and variations in the medium and temperature, there are also operational factors: the weighing accuracy of the test specimens before and after testing, the cleaning process of the specimens after testing, errors in the surface area of the specimens, and changes in the material composition of the specimens themselves – all of these can have an impact. Since these effects are random, there are additive or offsetting effects, which can result in significant variations. It is necessary to eliminate each influencing factor one by one in order to obtain results that are close to the actual values. Corrosion monitoring requires careful, thorough, and comprehensive analysis. This post was last edited by jessehjx on 2009-3-22 12:58.]
The differences in chemical treatment media are generally also quite significant
Patch corrosion monitoring can only assess the overall level of corrosion; changes in water quality during the period of using the patches may have an impact, and there are also differences in the treatment of the test pieces, all of which affect the results of each measurement. Only online electrochemical monitoring can provide real-time data, allowing it to detect the effect of changes in water quality and other conditions over time on the corrosion rate.
Temperature exacerbates pipeline corrosion, and pressure also contributes to it.
Factors such as the temperature, pressure, flow rate, and water content of the medium within the pipeline all have an impact
While differences and changes in medium and temperature cannot be ruled out, operational factors must also be taken into consideration: human factors, instrument factors, etc
It’s a normal phenomenon – one has to trade time for accurate values; the longer the measurement time, the more data is collected, and the closer the result gets to being accurate.
Firstly: the coupon method is designed for materials subjected to uniform corrosion. There are errors in the processing of the samples used in the tests, as well as in the removal of corrosion products, in the calculation of the corrosion area, and in the preparation of solutions; as a result, it is not possible to ensure that the test results will be identical each time； The probe method is primarily based on the environment in which the material is found; it involves a high degree of randomness, and its results can only serve as reference values. Secondly, your test results show very low values; the corrosion rate is between 1 and 10 micrometers per year, indicating that the material is quite resistant to corrosion.
The corrosion rate varies depending on the medium and temperature, and human errors are inevitable
There are too many factors; basically, they include the composition of crude oil (type of crude oil, acid value, sulfur content, acid content, and so on), operating temperature, flow rate and flow pattern of the medium, physical state, pressure, and material of the equipment.
Changes in operating conditions (temperature, pressure, etc.) affect the corrosion rate