Sensor Plates (BPI-2) are mounted to control the inner corrosion process on a regular basis in the most vulnerable parts of the pipelines. These products monitor the corrosion rate by applying the gravimetric method.
A sensor plate is a round steel 2 - 3 mm thick plate with a hole in the middle. The outer diameter of the plate is 50 - 60 mm, while the hole diameter is 12 mm. About 3 - 6 sensor plates are mounted on a holder which is welded to a blind flange. In assembled version the distance between them should be about 5 - 20 mm. BPI-2 is made from ВСт3сп or 10 and 20 steel grades in accordance with GOST 380 and GOST 1050, respectively. Visually the pipelines are inspected for the type of corrosion process, its rate is defined by analyzing the indicators in a particular time period.
It is necessary to have the data on the corrosion rate in different parts of the pipeline to assess the metal condition and water-chemistry condition of the pipeline. These data help to identify the reasons for pipe damage, to understand its impact on the service life of the structure and to take the appropriate measures. Regulatory documents divide the process intensity into four groups:
When calculating the rate of the corrosion-caused damages, it is important not to forget that with scale and rust on the sensor plates the calculated values are low. If the scale is soft and can be easily cleaned from the metallic surface, then the cleaning of the plates will help. At the same time the rate values of any similar process are likely to change from high to constant, but low ones. Therefore, it may take several months to set a balanced corrosion rate.
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