Regarding wall thickness inspection issues
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Dear friends: I would like to ask how wall thickness inspections are carried out in your refineries, and how often they are performed. We conduct inspections on a monthly basis. The problem is that the testing data varies greatly, and I even doubt its reliability>>> I would like to ask how others go about this – what instruments are used, and how are the thickness measurement points determined? How is the wall thickness of insulated pipes measured?
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I have never seen equipment called a \"Del thickness gauge\"; thickness measurement should be done using a thickness meter. Such meters need to be calibrated to ensure accuracy and reliability. The points where thickness is measured should be selected randomly – locations that are prone to corrosion, such as pipes, should be measured, with special attention paid to areas that are susceptible to corrosion and erosion, like the outside of elbows or the side walls of tees
If regular monitoring is required, it is recommended to establish fixed monitoring points on the equipment or pipelines. Create a plug or some other type of movable insulation element that can be easily opened at any time. Fixed monitoring points should be selected at areas where fluid impact is greater than in other parts; if possible, internal inspections can be carried out to identify areas damaged by corrosion or impact, for which movable monitoring points can be installed. It’s best to have two instruments for verification purposes. For reference
First is the selection of thickness measurement points (identifying the locations where thickness measurement will be taken and marking them). Next is the standardization of the thickness measurement equipment; generally, such equipment can be calibrated, and as long as it is used correctly, the accuracy of the data is quite high. Then there are the preparatory steps to be taken before measuring the thickness at these points (removing insulation, sanding any anti-corrosion coatings on the measurement points, cleaning the area to reveal the metallic surface, etc.)
First is the selection of thickness measurement points (identifying the locations where thickness measurement will be taken and marking them). Next is the standardization of the thickness measurement equipment; generally, such equipment can be calibrated, and as long as it is used correctly, the accuracy of the data is quite high. Then there are the preparatory steps to be taken before measuring the thickness at these points (removing insulation, sanding any anti-corrosion coatings on the measurement points, cleaning the area to reveal the metallic surface, etc.)
Ultrasonic thickness measurement, clean grinding, bonding agent
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Thickness measurement is carried out using an ultrasonic thickness gauge. The locations for taking measurements include straight pipe sections, elbows, tees, areas with diameter changes, sites of phase changes, and areas where chemical additives are used. The frequency of thickness measurements depends on the corrosion rate: for a corrosion rate of 0.3 to 0.5 mm/year, measurements are generally taken every 3 months; for a rate of 0.1 to 0.3 mm/year, measurements are taken every 6 months; and for a rate of less than 0.1 mm/year, regular maintenance inspections are sufficient.