About large pressure vessels
Pressure vessels are divided into storage and transportation vessels, reaction vessels, heat exchange vessels and separation vessels, which are widely used in petroleum, chemical, machinery, metallurgy, light industry, aviation, aerospace, national defense and other industrial production fields. In fertilizer, oil refining, chemical, pesticide, medicine, organic synthesis and other industries, pressure vessels are the main production equipment. For example, in ethylene plants with an annual output of 300000 tons, pressure vessels account for about 35% of the total equipment. The industrial field with pressure vessels as the main production equipment accounts for a considerable proportion in the national economy.
As pressure vessels belong to special pressure equipment, they have the risk of explosion and leakage. Therefore, pressure vessels need to strictly guarantee their product quality in the case of action principle, shape, vessel thickness, pressure bearing property, working temperature, placement form and manufacturing material, as well as sealing and various static, dynamic or alternating loads, and some additional mechanical or temperature loads.
Therefore, there are extremely strict requirements for measurement and detection in terms of the overall dimension, shape sealing and fit tolerance of the container.
Measurement requirements and key points of large pressure vessels
As shown in Figure 1, in manufacturing, it is difficult to accurately control the position relationship between the head and the connecting pipe when welding is used to complete the assembly of various parts. Therefore, it is necessary to use high-precision three-dimensional measurement and detection means to coordinate adjustment and verification to ensure the product quality. The measurement and detection accuracy of large pressure vessels is usually required to reach 0.2mm-0.3mm, and some pressure vessels applicable to special industries have higher detection standards.
During the survey, it is necessary to pay attention to the various geometric tolerance relationships between the following parts, and evaluate the relationship between flatness, coaxiality, position, etc. and conduct deformation analysis with high-precision standards within a large scale:
-Shell size and deformation;
-Position of tube plate and head relative to datum line;
-Nozzle position and flange flatness;
-Relative position relationship of each port;
-Flatness of datum reference end before welding.
API measurement solution
The Radian series high-precision
Laser Tracker, combined with the measurement scheme of portable three-dimensional laser scanner, can quickly realize high-precision detection of large pressure vessels.
Use Radian laser tracker to quickly determine the measurement datum, and establish a reference frame to measure the features of long-distance components; Combined with the use of 3D scanner to scan the local profile accurately, ensure that all measuring systems have a unified coordinate system, and take into account the measurement of local key points of size and shape.
For the above scheme, there are two common operation modes.
Measurement operation mode I:
Step 1, please refer to Figure 3. Set the 1.5-inch target seat firmly around the workpiece, which can be set according to the size of the workpiece. The interval between each two groups is about 6-8 meters. The workpiece shown in Figure 3 is 24 meters long, so set 4 groups, a total of 8 target seats;
The second step is to use the laser tracker for positioning, place the 1.5-inch target ball on the target base, measure the center position of the target ball, and establish the overall coordinate system (note: only one target ball is required for operation, and move to the next position for measurement after measuring one position, the figure is only a demonstration);
Step 3, please refer to Figure 4, place the 1.5-inch target ball of the 3D scanner on the target base for shooting and positioning, (divide it into two groups for shooting, and only one target base is needed), and align the four positioning coordinates obtained by each group to the overall coordinate system of the tracker.
About the alignment of coordinate system: the target of the tracker and 3D scanner is 1.5 inches, so its center point is the same position. Finally, the coordinate system can be unified by one-click command.
Measurement operation mode II:
The first step is to measure the hole position of the front and rear flange ends and the side flange ends with a high-precision laser tracker, and establish a coordinate system;
The second step is to use a 3D laser scanner to collect three hole positions at the front, rear and side flange ends respectively, and then align the scanning data to the coordinate system based on the hole positions measured by the laser tracker, so as to unify the detection data and the scanning data to the same coordinate system.
During the measurement, not only can the information of the measured part be collected quickly through the tracker, but also the deformation of each local surface can be analyzed quickly after the scanner unifies the coordinate system.
Scheme advantages
Features&keywords: spatial geometry measurement, geometric tolerance analysis, large size high-precision frame positioning, assembly adjustment.
1. Radian series laser tracker can quickly detect the spatial geometric relationship of large size and high-precision workpiece under complex working conditions, and provide a high-precision framework basis for the subsequent fine local measurement;
2. Radian's built-in Autolock automatic light receiving function can automatically and quickly search and lock the target ball in case of light failure, and continuously conduct rapid data acquisition and accurate comparison and analysis at the measurement rate of 1000 points/second. Autolock active vision module provides a field of view angle of more than 30 ° and supports free movement measurement in a large range;
3. This case can not only provide effective correction data support in the measurement of finished products, but also provide the basis for efficient adjustment in the welding and assembly process, to avoid subsequent
Repair of defective products, and greatly save the production cycle and cost.
conclusion
API brand Radian series laser tracker with ultra-high accuracy (micron level, μ m. 0.001 mm), which provides a convenient and efficient dynamic measurement and real-time adjustment guidance solution for all large workpieces and systems, greatly shortens the time for the commissioning and welding of the position relationship of pressure vessel components in the process of production and delivery, effectively controls the production and time costs, and provides a strong guarantee for the smooth implementation of the overall progress of the project.
