Present status: During the regular inspection of industrial pipelines and equipment, we will pay great attention to the development status and corrosion status of internal defects in the welding position, because this is directly related to the safe use period and safety of the equipment. Conventional film inspection mostly uses the blackness comparison method to roughly infer the depth of the defect, for example, comparing the blackness of the circular defect with the blackness of the base material to determine whether it is a deep hole. The digital radiography system adopts a similar processing method to film detection. It also uses the gray scale contrast method to infer the approximate depth of defects. It is difficult to accurately determine the depth of defects, especially crack defects, unless it is a very serious opening defect, blackness or gray. The degree will be very obvious. For superficial and extensible cracks, it is very difficult to judge the crack depth by gradation or blackness, which gives the special equipment inspectors an excellent uncertainty in accurately evaluating the safety cycle of pipelines and equipment. Generally, in case of suspected problems, special equipment inspectors will issue rectification notices or request suspension of use, but the on-site equipment is sometimes flammable, explosive, and high-temperature places, maintenance is inconvenient, and shutdown maintenance will also be given to the production enterprise. Caused huge economic losses.
Background: The timely and efficient digital imaging provides a technical basis for monitoring welding defects and corrosion. How to measure the depth of welding defects and corrosion? How to judge the development speed of welding defects and corrosion depth? How do you combine measurement defects and corrosion depth with the depth of defects and corrosion development on the safety equivalence rating of equipment? How can the development of defects be within our control and within the estimated range? In this way, the equipment can be safely and stably operated with defects, saving a lot of resources and energy for the country and the enterprise.
Features: Digital ray imaging is based on two-dimensional planar imaging. The measurement of defects and corrosion depth has always been a difficult point in ray detection. Now, we can accurately measure the depth of defects through precision calculation of precision grooved test blocks and imaging software, and provide a reliable basis for online evaluation of equipment. The test block has an accuracy of 0.05, 0.1mm from 0.1mm to 10mm, and considering the cross-sectional shape of the workpiece, we have prepared different sets of test pieces for the plate and the pipe. The depth of defects and corrosion can be accurately calculated by computer software, which can be divided into the following two methods:
1) Defect, corrosion depth and test block depth are in the same state
a) First find the location of the pipe defect, and then cover the blank area of the ring test block to the location of the defect, as shown below:
b) Draw a line along the calibration line to the calibration line of the ring test block, as shown below:
c) Observe whether the defect line and the calibration line peak of the ring test block are on the same horizontal line, as shown in the following figure:
If the defect point shown in the above figure is at the same position as the calibration line of the 0.9 mm depth of the annular test piece, the defect and the depth of corrosion can be determined to be 0.9 mm.
2) Defects, corrosion depth and test block depth are in different states
a) Depth in the middle of the two calibration lines, use the measurement method to first find the location of the pipeline defect, then cover the blank area of the annular test block to the location of the defect, and also along the calibration line from the location of the defect to the annular test block. A straight line, as shown below:
b) Select the defect location as shown below:
c) Select position 1 and enter the known depth of position 1, as shown in the following figure:
d) Select position 2 and click the calculation button to get the depth of the defect, as shown below:
The emergence of the accurate measurement function of the ray digital imaging software solves the problem of defect depth measurement, provides a technical basis for the assessment of the safety status of special equipment in national production, and provides a guarantee for the safety of life and property.