Monitoring method for residual fatigue life of expansion joint bellows

Abstract

The invention provides a monitoring method for the residual fatigue life of an expansion joint bellows. According to the method, the displacement amount of the expansion joint bellows in the working state is measured in real time through a sensor, and then the displacement amount is transmitted to a PLC. The PLC calculates the w fatigue lives [Ncw] of the bellows during the next time period m in the working state, wherein w is equal to 1, 2, 3 and so on. In this way, the residual fatigue life Nrf of the expansion joint bellows is obtained, wherein [Nc] is the designed fatigue life of the bellows. The PLC displays the residual fatigue life of the bellows and carries out the early warning and the alarming when the residual fatigue life reaches a preset alarm value. According to the invention, the operation state and the residual life of an expansion joint can be monitored in real time. Meanwhile, the remote early warning function and the alarming function are provided. When the temperature, the pressure or the displacement exceeds rated values, the remote alarm is carried out. The on-site maintenance and the on-site repair are facilitated. The workload of the pipeline maintenance personnel is greatly reduced, so that the safe operation of pipelines can be more efficiently ensured.

Description

technical field [0001] The invention relates to an expansion joint, in particular to a method for monitoring the remaining fatigue life of an expansion joint bellows. Background technique [0002] Metal bellows expansion joint is one of the key components for thermal compensation of modern heating pipe networks and equipment, and has the functions of displacement compensation, vibration reduction, noise reduction and sealing. At present, it has been widely used in thermal pipelines, process piping, machines, pumps and pressure vessels in various industrial sectors such as metallurgy, oil refining, petrochemical industry, electric power (thermal power, hydropower and nuclear power), heating network, shipbuilding, construction, cement, aerospace and machinery. Wait for the device. However, the expansion joint is a structural element with a certain service life. When the expansion joint is used for a certain period of time, the expansion joint will be damaged. In addition, in ...

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Problems solved by technology

However, the expansion joint is a structural element with a certain service life. When the expansion joint is used for a certain period of time, the expansion joint will be damaged. In addition, in the actual work of the expansion joint, there are damages caused by multiple working conditions such as driving and parking. Fluctuations in temperature, pressure, displacement and other loads cause multiple fatigue cycles of the product, which have an important impact on the fatigue life of the bellows. Regular manual inspection is required for timely maintenance. The existing monitoring technology only provides early warning when the bellows fails. Provides early warning and alerts during lifespan monitoring

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