Pressure Detection Technology Based On Fiber Bragg Grating Pipeline

As a special kind of equipment to deliver materials, pressure piping plays an important part in industrial production and our life. The mediator is mostly fluid with strong corrosive characteristics. During the delivering process, the iMPact of the hydraulic pressure due to the corrosion of the fluid, the change of the temperature and the pressure control and other factors such as man-made sabotage, can easily cause operation trouble of the piping delivering system, which could endanger people's lives and properties, and thus real time monitoring over the piping delivering condition is quite necessary. The basic parameters of piping materials and supplies include pressure, temperature and rate of flow and so forth. Among them, the delivery of the materials and supplies is mainly maintained by the pressure energy, that is, the pressure difference inside the piping. Therefore, the key to ensure the safe and steady operation of the whole piping system is the monitoring of the piping pressure and the control of the delivery pressure inside the piping. Therefore, the real time monitoring of pressure appears rather important. At present, the traditional way to test the piping pressure is the intrusive measurement; that is, installing a pressure sensor on the spot where the pressure is tested. Through this the pressure sensor component directly contacts the mediator which is being tested. Generally, this would cause damage to the integral features of the piping and the flow field inside the piping, especially accidents could happen under heavy pressure.This paper refers to a non-intrusive fiber Bragg grating piping pressure measurement based on deformation of the piping and does theoretical analysis and experimental research on the piping pressure measurement under the internal pressure. The pressure piping uses carbon construction steel (GB/700-1999) Q195 pipe welding used to deliver low pressure fluid with 500 mm in length,114 in external diameter and 2 in thickness. Its dimensions refer to piping dimensions series of the national application standard system, which is GB/T17395. Loading and unloading the piping pressure could be done by the SB-4.0 manual hydraulic test pump. The main completed work as follows:(1) Due to the internal pressure, the compression stress is produced in the piping along the ring and the axis, which accordingly leads to the displacement of the Bragg wavelength of the fiber Bragg grating which is attached at the outer wall of the piping along the ring and axis. A mathematical sensor model can be established through the theory.(2) According to the elasticity analysis of the thick-wall cylinder, that is the Lame stress formula, with the broad-sense Hooke law, put the related parameters into the mathematical model of the piping pressure measurement and work out the response rate along the ring and axis, which are 179.6 pm/MPa and 37.9 pm/MPa respectively; the theoretical resolution ratios are 0.006 MPa/pm and 0.026 MPa/pm separately.(3) Tests showed that the measurement sensitivity along the ring and axis of the piping is 181.1 pm/MPa and 26.7 pm/MPa respectively; the real resolution ratios are 0.006 MPa/pm and 0.037 MPa/pm separately.