Pressure vessel is a comprehensive product involving multiple industries and disciplines, and its construction technology involves metallurgy, machining, corrosion and corrosion protection, nondestructive testing, safety protection and many other industries. With the continuous progress of metallurgy, machining, welding and non-destructive testing technologies, especially the rapid development of information technology represented by computer technology, which has driven the development of related industries, the world has invested a lot of human and material resources in in-depth research based on the field of pressure vessel technology has also made corresponding progress. In order to produce and use safer and more economical pressure vessel products, the traditional design, manufacturing, welding and inspection methods have been and are being replaced to varying degrees by new technologies and products.

1, pressure vessels used in the technical progress of materials in recent years, the pressure vessel products large-scale, high-parameter trend is increasingly evident, thousand-ton hydrogenation reactor, two thousand tons of coal liquefaction reactor, 10,000 cubic meters of natural gas spherical tank (Japan's largest natural gas spherical tank for 30,000 cubic meters), etc. have been used in large numbers in China, pressure vessels in the petrochemical industry, nuclear industry, coal chemical industry and other fields of application occasions are Increasingly demanding. Therefore, high temperature, high pressure and corrosion-resistant pressure vessel materials research and development has been a major issue facing the pressure vessel industry. In this regard, countries have invested a lot of human and material resources in the relevant research work. At present, the main research results and technical progress of the pressure vessel materials in the following areas: high purity of the material: the overall level of technology and equipment of the metallurgical industry to improve the level of purity of the material, improve the mechanical properties of the pressure vessel materials to improve the overall safety of the pressure vessel; media applicability of the material: for a variety of corrosive media and operating conditions, has Research and development of super stainless steel, duplex steel, special alloys and other metal materials to make it suitable for a variety of application conditions, to give designers more room to choose, to provide a guarantee of long-cycle safety production; material application boundaries: for high-temperature creep, tempering embrittlement, low-temperature brittle fracture of the research conducted to accurately give the scope of application of the material.

The application of higher strength materials: In the requirements of large-scale equipment, traditional materials have been unable to solve the problem of material selection such as 30,000 cubic meters of natural gas spherical tanks, large spherical tanks in steel mills, 200,000 cubic meters of crude oil storage tanks, and ultra-high pressure vessels. The application of σb ≥ 800MPa high-strength materials is currently attracting widespread attention of domestic researchers.

2, the wide application of computer technology in the information age today, the application of computer technology has penetrated into every area of the pressure vessel industry. Every progress of computer software and hardware greatly affects the technical progress of the pressure vessel industry, which is mainly manifested as follows: design: the traditional computer-aided design (CAD) has gradually developed to the direction of computer-aided engineering (CAE). With the continuous enhancement of computer capabilities and increasingly diverse means of analysis, designers in the structural design phase can anticipate problems such as residual stresses generated in the welding process, equipment assembly and transportation process may appear in the collision, and in the design phase to eliminate these problems, analytical design and structural optimization design has gradually for the designer to master; manufacturing: computer-aided manufacturing (CAM) Technology is gradually changing the traditional process of pressure vessel manufacturing plant production methods, quality management awareness and production methods have undergone profound changes. The whole process of pressure vessel computer management makes all control points can be effectively controlled, greatly reducing human error, effectively ensuring the stability of product quality, production cycle and production cost reduction; welding: computer-controlled copy welding machine, laser welding machine and the application of all-position automatic welding machine, greatly improving the production efficiency and product quality; nondestructive testing: computer ray real-time Imaging, ultrasonic scanning simulation imaging and multi-channel acoustic emission and other technology applications, coupled with specially developed expert systems, so that the results of the test more accurate and objective. In particular, the ultrasonic scanning simulation imaging defect detection technology (TOFD) has been successfully used for nuclear equipment, hydrogenation reactors and other heavy vessels with thickness greater than 100mm. This has played a positive role in improving the production efficiency of heavy vessels and reducing ray contamination. China began to apply the technology in the construction of coal liquefaction plant reactors to solve the problem of non-destructive testing conducted on site.

3, structural design of modern pressure vessel structure design is gradually getting rid of the traditional concept, reflecting the design concept of truly meeting the requirements of the process, the pursuit of effectiveness, safety and economic harmony and unity.

Rational design of the structure: the specific structural form of the pressure vessel is not restricted in the standard, so the pressure vessel structure is subject to fewer constraints, giving designers a lot of room to play, which is conducive to the design of a more reasonable structure. In addition, the use of analytical design tools and the implementation of validation tests for the rational design of the structure provides the necessary protection. For example, the modular design method, it is in accordance with the different functions of each component on the pressure vessel will complete the same function of each component as a small whole to study, such as the safety protection device part, the tank part, etc., it not only makes the maintenance of pressure vessels easier, but also to a large extent can shorten the development cycle, accelerate the technology upgrade.

Economic design of the structure: The harmony of safety and economy of the pressure vessel has always been the pursuit of the designer, and the stress analysis standard is the emergence of this requirement. The use of welded steel pipes and the application of special structures are largely considered the economy of the pressure vessel structure.

Structural reliability design: the traditional safety factor design method in order to "insurance", often the value of the safety factor is large, making the design of the pressure vessel and parts of the structure size is large, not only a waste of material, but also due to the life and strength of each part is difficult to ensure a reasonable match, resulting in the final product 1 + 1 < 2 The result is that the final product is 1+1<2. The reliability design treats part of the parameters as random variables, and establishes statistics and statistical models to calculate with probability statistics, which can scan all the design objects and the results are more in line with the world situation.

4, the reduction of the safety coefficient in order to increase the competitiveness of their products, reduce the safety coefficient is currently the general tendency of the world and regional pressure vessel standards, our country also proposed a specific material designed according to the analytical design method to reduce the safety coefficient nb to 2.4 proposal. The reduction of the safety factor is related to the basis of pressure vessel standards, the economy and safety of the pressure vessel industry has a great impact, must be careful and prudent. The preconditions for reducing the safety factor are: improvement of the level of structural analysis and design; accumulation of manufacturing experience and improvement of manufacturing technology; more stringent material technology requirements; and more scientific quality assurance system.