Research On The System And Method Of Acoustic Measuring Thickness Of Wellhead High Pressure Manifolds

Pipes have become the fifth new mode of transportation and have been widely used inliquid and gas medium remote transmission. Nearly half of pipes in our country haveworked for more than20years and more than50%of global pipeline network area hasbecome aging. As a result, the leakage and explosion accidents rate is pretty high. In highpressure pipelines, manifold’s wall thickness is the most vulnerable to become reduce,therefore its detection is necessary in the online wall thickness monitoring. This paper putsforward a method using electromagnetic ultrasonic and dry coupling piezoelectricultrasonic to detect the wall thickness and then develops a relevant monitoring system.First of all, the influences of electromagnetic ultrasonic probe’s parameters on the wallthickness signal have been analyzed through theory and series of experiments. Then thispaper optimizes the exciting coil structure and bias magnetic field implemental methodsand develops an electromagnetic ultrasonic detection system based on piezoelectricity forthe purpose to obtain the highest sensitivity. At last the feasibility of the manifold detectingis analyzed.Due to the low signal noise ratio when using electromagnetic ultrasonic to detectmanifold material, dry coupling piezoelectric ultrasonic thickness detecting method is putforward. In order to study dry coupling material acoustic transmission rate, this paperresearchs a method to detect material impedance based on ultrasonic echo, deduces theformulas to calculate material acoustic transmission rate and researches the relationshipbetween material thickness and transmission rate. Through experiments it can be found thatmanifold material has bigger influence in transmission rate, what’s more the transmissionrates of aluminum cooper and cast iron decrease sequentially. Thus, appropriate drycoupling strip and its thickness is selected in the experiments.In this thesis, a high pressure manifold wall thickness dry coupling ultrasonicmonitoring system is designed, a high pressure manifold dry coupling probe and itsinstalling structure is invented. This system can be used to control large scale probessynchronously. Experiments show that transmission distance has only small attenuation on monitoring signal, the control system is stable and the uneven surface of manifold has alsolittle attenuation on thickness signal. That is to say this system can realize the high pressuremanifold thickness online continuous monitoring.