非焊透阶梯导波杆用于高温管道超声测厚的实验研究

Experimental study on the high temperature pipeline ultrasonic thickness measuring with partially welded stepped wave guide

将与管道材料相同的阶梯导波杆以非焊透的形式垂直地焊接在管道监测部位,导波杆的中上部设置冷却装置,使端部温度降低以便使用常规超声波探头及耦合剂进行测量,从而实现高温管道壁厚超声波监测.以碳钢材料为例,利用数字超声波探伤仪CTS-2020对焊接导波杆的圆平板进行了测量.只要保证导波杆阶梯段的温度接近被测构件的温度,利用阶梯段的已知长度及各反射波声程差,不需修正即可推算圆平板的厚度.与圆平板实际厚度相比,误差小于0.15 mm,可满足高温管道壁厚检测要求.

The high temperature pipeline thickness was suggested to be measured with an ultrasonic stepped wave guide,which is partially welded on the monitoring point of the pipeline vertically. The cooling unit at the up-middle part of the guide was used to cool the temperature of the guide end low enough to hold the conventional ultrasonic sensor and coupling medium. Taking carbon steel as an example, circular plate with such a waveguide was experimentally studied with digital ultrasonic flaw detector CTS-2020. It is found that the plate thickness can be deduced with the known length of the stepped section and the sound journey differences of the reflecting waves. It can be deduced directly without modification of temperature on the sound velocity when the temperature of the stepped section of the waveguide is ensured to be close enough to that of the measuring component. Compared with actual plate thickness, the absolute error of the deduced thickness is no more than 0.15 mm, which can meet the need of the high temperature pipeline thickness monitoring.