Research And Implementation Of Safety Valve On-line Test System

Safety valves have been widely used as an overpressure protection device in the industrial production units of process industry. In order to ensure the safety of production unit, safety valves were required to test at least once per year. Currently, Off-line test method is commonly used, however, when conducting off-line test, the production units should be in a stutdown state for disassembling valve to test, which , in this case, is not in accordance with the requirement of long-period operation in process industry. The current standard regulations don't given clearly defined specification in terms of the inspection period of safety valve under different service conditions. Off-line test method is still subject to disassembling conditions, long-time and high-cost test problems. In addition, because of immaturity of the existing opening criterion (a criterion to judge if the valve clack is open) and the shortage of the use experience, safety valve on-line test devices are not broadly applied. Aiming at these problems in off-line and on-line test, this paper developed an on-line test device by using mechanical-electrical-hydraulic integration technology. A method to determine the inspection period of safety valve in different failure mode is proposed according to historical data records. The main work and the results are as follows:1) According to the regulation of national standard GB12242-2005《Pressure Relief devices Performance Test Code》, a mechanical-electrical-hydraulic integration on-line safety valve test device, which is composed by mechanical clamp structure, hydraulic-driving system and electrical test system, is developed by utilizing the technique of hydraulic transmission, sensor and data acquisition and processing. According to the mechanical characteristics of the test device, opening criterion based on the feature point method is proposed. A trestle table for safety valve test is designed, and finally, safety valve test system is constructed, experiments are conducted to verify the usage of the device. The results show that the opening criterion based on feature point method is feasible, the safety valve test device are capable to test safety valve both under off-line and on-line condition, which meet the requirements of the corresponding standards GB12242.2) Management mode of safety valve centering on test institution is proposed by combing with the regulation of safety management for safety valve. Based on the management mode, the safety valve management software platform which is composed of information management system, test information management system and reliability data management system, is developed by utilizing database technology and object-oriented technology. The software platform can data acquisition, process, and analysis during the procedure of safety valve on-line test. it also can manage the daily inspection and maintenance of safety valve. the function of reliability data management needs to be further improved.3) Basing on the statistical data of historical proof test, the method to evaluate inspection period in different industries under the influence of failure mode combining FMEA method and quantal response analysis method is proposed. Providing theoretical support for formulating relevant laws and regulations and safety valve management.