Pressure vessel is a comprehensive product involving many industries and many disciplines, and its construction technology involves many industries, such as metallurgy, mechanical processing, corrosion and corrosion protection, nondestructive testing, safety protection and so on. Along with the development of metallurgy, mechanical processing, welding and non-destructive detection technology continues to progress, especially the rapid development of computer technology as represented by information technology, led to the development of related industries in the world, a lot of resources on the basis of thorough study, the technical field of pressure vessels has made some progress. In order to produce and use more secure and more economical pressure vessel products, the traditional design, manufacture, welding and inspection methods have been and are being replaced by new technologies and products in different degrees.
1 pressure vessel products of large-scale, high participation in recent years the number of the trend is more and more obvious, the hydrogenation reactor, thousands of tons of coal liquefaction reactor, two thousand tons of ten thousand cubic meters of natural gas spherical tank has been used widely in our country, application of pressure vessel in the petroleum chemical industry, nuclear industry, coal chemical industry the increasingly harsh. Therefore, the research and development of materials for high temperature, high pressure and corrosion resistance of pressure vessels has been a major issue faced by the pressure vessel industry. In this regard, the country has invested a lot of manpower and material resources to engage in related research work. At present, the main research achievements and technical progress of the materials used in the pressure vessel are shown in the following aspects:
High purity materials: metallurgical industry overall technical level and equipment level, greatly improve the purity of the material, improve the mechanical properties of materials for pressure vessels, improve the overall safety of the pressure vessels;
Applicability of media materials: for all kinds of corrosive media and operating conditions, has developed the super stainless steel, two-way steel, special alloy and other metal materials, which is suitable for various application of price adjustment, which gives the designer more choices of space for long period safety production guarantee;
Application boundary of materials: Aiming at the research of high temperature creep, temper brittleness, low temperature brittle fracture, the application range of the material is given accurately.
Application of high strength material in large-scale equipment requirements, traditional materials have been unable to solve such as 30 thousand cubic meters of natural gas tanks, steel large spherical tank, 200 thousand cubic meters of crude oil storage tank and material of super high pressure vessel. At present, the application of more than 800MPa high strength material is attracting wide attention of researchers in China.
2 the wide application of computer technology
In the information age today, the application of computer technology has penetrated into every field of pressure vessel industry. Computer software and hardware, each of which has greatly influenced the development of the pressure vessel industry:
Design: the traditional computer aided design has been gradually developed to the direction of computer aided engineering. With the constant enhancement of the ability of computer and analysis means of increasing diversity, problems in the structure design stage, designers can foresee the residual generated in the welding process such as collision may occur stress, equipment assembly and transport process, and eliminate these problems in the design phase, design and structure optimization design and analysis has been gradually as the designer master;
Manufacturing: computer aided manufacturing technology is gradually changing the traditional way of production, quality management and production methods of the pressure vessel manufacturing plant has been a profound change. The whole process of computer management of pressure vessels (* o *) all control points can be controlled effectively, that greatly reduces the errors, effectively ensure the stability of the product quality, reduces the production cycle and production cost;
Welding: application of computer controlled welding machine, laser welding machine and profiling of all position automatic welding machine, greatly improve the production efficiency and product quality;
Non destructive testing: the application of computer - ray real - time imaging, ultrasonic scan imaging and multi - channel emission technology, and then with the expert system developed specifically to make the test results more accurate and objective. In particular, ultrasonic scanning simulation imaging flaw detection technology has been successfully used in nuclear equipment, hydrogenation reactor, such as thickness of more than 100mm of heavy vessels. It has played a positive role in improving the production efficiency and reducing the pollution of the heavy vessels. In the construction of the reactor of coal liquefaction plant, the technology is applied to solve the problem of non destructive testing in the field.
3 structure design
Modern pressure vessel structure design is gradually getting rid of the shackles of the traditional concept, reflect the real, to meet the technological requirements of the design concept, the pursuit of effectiveness, safety and economic harmony and unity.
Reasonable structure design: the specific structure of pressure vessel standards are not restricted, so the structure of pressure vessel are less constrained for designers to play a lot of space, help design a more reasonable structure. In addition, the application of the design method and the implementation of the verification test provide the necessary guarantee for the rationality of the structure design. The modular design method for example, it is in accordance with the components of pressure vessel components with different functions will perform the same function as a whole to study, like the safety protection device, part of tank, it not only makes the pressure vessel maintenance more convenient, but also can shorten the development cycle in the a large extent, accelerate technological upgrading.
Structural economic design: the safety of pressure vessels and economic harmony has always been the pursuit of the designers, the stress analysis standard is the emergence of this requirement. The use of welded steel pipe and the application of special structure, to a large extent, is to consider the economic structure of the pressure vessel.
Reliable structural design: safety coefficient design method for traditional &ldquo insurance; ” reasons, often safety coefficient is too large, the pressure vessel and the structure and size of the parts design is too large, not only waste materials, but also because of the various parts of the life and strength to ensure the reasonable match, resulting in the final 1+1< 2. The reliability design will be some parameters as random variables, and carries on the statistics to establish a statistical model, using probability statistics method to scan all the design object, the results accord with the situation of the world.Finally, in order to increase the competition of domestic products, reduce the safety factor is a general tendency of Pressure Vessel Standards of the countries and regions of the world at present, our country has put forward the safety coefficient NB of specific material relates to design by analysis method is reduced to 2.4 of the proposal. The reduction of safety coefficient based inverted pressure vessel standard, a great impact on the economy and safety of pressure vessel industry, must be cautious. The precondition of reducing the safety factor is the improvement of the level of structural analysis and design, the accumulation of manufacturing experience and the improvement of manufacturing technology level, the more strict requirement of the material technology and the more scientific quality assurance system.