Potential Drop Strain Sensor for Creep Monitoring

Creep is a high temperature damage mechanism of interest to the power industry and at present lacks a satisfactory monitoring technique. Existing material inspection techniques are extremely laborious while strain measurements rely on often infrequent off-load measurements. A quasi-DC directional potential drop technique is presented that is shown at both room temperature and at high temperature to act as a robust strain gauge. Resistivity changes that are expected to occur in high temperature environments are also discussed as a source of potential error in strain measurements.

On-Line Health Monitoring Research on T-Joint of Main Steam Piping

The main challenge of long-time creep monitoring on site is a reliable sensor. In this paper, a sensing device is developed specifically for high temperature creep monitoring. And it is applied to on-line monitor the strain of material on T-joint of main steam piping. Its reliability is verified theoretically using the finite element method and experimentally by high temperature on site test. The creep damage of the T joint is evaluated basing on the creep rate sensed by the sensing device. And the residual life is predicted for the piping system using the Monkman-Grant equation. This system is useful for safety assessment procedures in thermal power plant, nuclear power plant and petrochemical industries.