Research On Wall Thickness Corrosion Detection Technology Of High Temperature Pipeline Based On Ultrasonic Guided Wave

The pipeline plays an important role in the transportation of gases and liquids,and is considered the lifeblood of the national economy and livelihood.With the increase in service time,corrosion under the influence of transmission medium and the external environment becomes more and more common.Particularly,high temperature,high pressure and corrosive medium will considerably accelerate corrosion,thin the wall thickness and raise the leaking risk.As a result,real-time monitoring of high-temperature pipeline wall thickness can aid in estimating the remaining life,which is useful for pipeline maintenance and replacement.A waveguide was constructed according to the UGWT,and the specific factors impacting the cooling effect of the waveguide were investigated based on the controlled variable method.The GW propagation mechanism was analyzed using FEM.The anti-plane shear loading method was used to excite the SH wave in the waveguide,and the stainless steel plates of various thicknesses were measured using the pulse-reflective principle.A non-invasive ultrasonic wall thickness detection device was built for experimental verification.The thermal simulation results showed that the waveguide rod’s shape,material,and size were the main factors affecting its cooling effect.The rectangular waveguide rod made of SS316 L with a length of 300 mm and a large width-thickness ratio had a remarkable cooling effect.The SH wave had low dispersion and a strong echo-signal amplitude when the waveguide width was 18 mm～20 mm and the excitation signal frequency was 1.0 MHz～1.4 MHz.Using an ultrasonic coupling agent with increased viscosity and acoustic impedance and a specific thickness of 0.6 mm improved the transmission rate of acoustic energy.The acoustic simulation results showed that the thickness measurement error of the double waveguide rod was slightly higher than that of the single waveguide rod,but it was more advantageous in detecting thick plates and pipes,and the measurement error decreased as the thickness increased.The dry coupling fixture used in the experiment significantly reduced the thickness measurement error.The double waveguide rod with one transmitter and one receiver method achieved indirect measurement of high-temperature pipeline wall thickness,which solved the problem that piezoelectric ultrasonic probes cannot be directly applied to high-temperature environments and had engineering application value.