Ultrasonic Inner Inspection Technique Research On Long Distance Pipeline

The pipeline as a kind of safe and economical carrying means of transporting a mass of energy sources, such as oil, gas and so forth is applied widely in every place of the world. For the sake of guaranteeing their safe movement and prolonging their life, the in-service pipelines should be inspected periodically in order to discover the problem and adopt the measure timely. Based on the need for pipeline inspection of local petroleum operation department, the thesis carries through the design and development of long-distance pipeline ultrasonic inspection pig (US-Pig). Moreover, aiming at the difficulty of data collection, the synchronous collection and memory problem of thickness data and the orientation data have been resolved by adopting the methods of combining software with hardware. However, the traditional simulative ultrasonic inspection system is always along with some problems such as errors and lower Signal-to-Noise and so on. To these shortages, a scheme of inner inspection system of long distance pipeline based on digital ultrasonic inspection is put forward. Using some key components such as embed computer and special high-speed data collection clip, digital ultrasonic pipeline inspection has been completed with good results. Having done careful research with enough analysis, a new improved Burg maximum entropy spectral estimation method named after second order prediction-error-filter coefficients re-deducible algorithm has been advanced for enhancing measurement precision even more in the article. In addition, the key algorithm of the classic periodogram spectrum estimation has been improved with split-radix algorithm that can shorten the time of program executing. The validity of them has been proved by verification.By the theories argument and experiment measurement, the digital ultrasonic inspection system designed in this article can overcome some inherent disadvantage of simulative ultrasonic inspection system and accomplish the task of on-line pipeline inspection. The advance of improved algorithm has enhanced the precision and speed of ultrasonic thickness measurement that can satisfy the engineering demand.