Problems and solutions of the hottest pressure ves

Problems and treatment of in-service pressure vessels since the implementation of the regulations on the supervision of special equipment in China, the effect has been remarkable, and the accident rate of boiler pressure vessels has greatly decreased. Through the qualification examination and licensing work, the quality problems of the design, manufacture and installation of pressure vessels in China have been basically controlled. At present, the more urgent problem is to rectify the use and management of pressure vessels

through the general survey and inspection of pressure vessels in recent years, we have basically found out the problems of pressure vessels in use, and mastered the general law of the occurrence and development of vessel defects

material problem

pressure vessel is a kind of special equipment. The manufacturing conditions and use bars. On the contrary, the steel used for pressure vessel must have qualified strength, high elongation and impact performance, and low impurity content such as sulfur and phosphorus. In principle, synthetic fiber materials with high pressure performance should be used. In the future, the supply of steel used for pressure vessel will certainly exceed the demand. However, due to the short supply of steel for pressure vessels in previous years, China had to partially use non pressure vessel steel. China allows the use of class a steel in ordinary carbon structural steel. Class a steel only provides two guaranteed items of mechanical properties and sulfur and phosphorus content. Therefore, when using class a steel to manufacture pressure vessels, its scope of use must be strictly limited. Therefore, we can't take simple measures to solve the problems of unclear materials and materials used in pressure vessels in use that do not meet the standards and specifications in the past. In principle, we should deal with them according to the following methods:

for low-temperature, highly toxic, high-temperature and high-pressure vessels, their material selection should meet the requirements of standards and specifications. For vessels with unclear materials or performance that do not meet the requirements, they should be stopped from use or renewed within a time limit or used for other purposes

for other pressure vessels, emphasis should be placed on the inspection of the actual technical conditions of the vessels. If the defect of the container is caused by improper use of materials, it should be stopped or used for other purposes; If the container is in good technical condition, it can continue to be used; If the technical condition of the container is poor, the defect is serious, and the material does not meet the standards and specifications, it should be handled carefully according to the specific situation, or stop using, or use within a time limit

internal defects of welds

due to the low qualified rate of nondestructive testing of the internal welds of pressure vessels in use, a considerable number of vessels have been found to have excessive defects inside everywhere through nondestructive testing. However, after the container has been used for ten or twenty years, the quality remains the same. No surface cracks are found on the internal and external surfaces of the weld through macroscopic or surface inspection. According to the film analysis, most of the internal defects are generated in the manufacturing process. Therefore, it can also be said that the defects inside the weld are at least stable for the container bearing static load, and basically do not change with time. Compared with weld surface defects, its impact on the safety life of containers is indirect and secondary. Although the internal quality does not meet the quality control standard, that is, the quality is unqualified, it can still be used

based on the above point of view, in the general survey, the treatment of defects in the weld joint of the pressure vessel in use, which should be clamped symmetrically with the jaw according to the requirements, is based on the stress level of the vessel, the nature of the defects, the service conditions and other technical conditions, and the following principles should be adopted to treat them differently

crack defects may lead to catastrophic accidents in the use of pressure vessels, so it is generally used to weld repair after eliminating crack defects, so as to reduce the pollution caused by waste water and waste gas

the treatment of other defects should also be judged in accordance with the specific conditions of the container

safety management

due to historical reasons, the use and management of pressure vessels in China are not strict, the basic work of pressure vessel safety management is poor, and the quality and safe operation of pressure vessels are lack of guarantee. Despite several years of efforts, the accident rate of pressure vessels has decreased year by year. However, some units, groups or individuals still design and manufacture without certificates. These units have poor general conditions and lack of supervision. Therefore, the manufacturing quality is far from meeting the requirements of standards and specifications, which is a serious problem in the safety supervision of pressure vessels at present

in addition, safety supervision on the use and management of pressure vessels should be strengthened at present. The author suggests to review the safe use conditions of the user units, mainly including:

review the safety management system of pressure vessels (including the vessels manufactured by non designated units shall not be purchased) and the regular inspection system; Implement the management organization and safety technical management personnel of pressure vessels; Assess the safety technical management personnel and vessel operators of pressure vessels, and take the post only after passing the examination

the above conditions shall be reported to the local quality and technical supervision department for filing after passing the examination, and then the pressure vessel registration form can be issued. In this way, it is not only conducive to improving the awareness of the staff of the competent department on the safety management of pressure vessels, and fully mobilize and give play to their positive role, but also strengthen and improve the safety work of the user unit itself. At the same time, the quality and technical supervision department is paying close attention to the general survey, registration and certification of in-service pressure vessels. The regular inspection of containers should be included in the agenda, the contact with the competent departments of enterprises should be strengthened, and unified planning and deployment should be carried out