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Spiral welded steel pipe weld eddy current nondestructive testing method
Date:2024-05-29      View(s):137      Tag:spiral welded pipe, welded steel pipe, spiral steel pipe testing
Pipeline transportation, as an efficient special transportation means, has played an increasingly important role in the fields of oil and gas transportation. Domestic large-diameter transportation pipelines are currently mainly constructed with spiral welded steel pipes. To ensure the reliable operation of the transportation pipeline, the quality of the spiral steel pipes used must be strictly guaranteed. Therefore, the research and adoption of an effective online ultrasonic automatic flaw detection system has become an inevitable choice for steel pipe manufacturers. Compared with foreign countries, my country's testing equipment level is relatively backward. The detection of steel pipe welds is carried out by manual or semi-automatic equipment. Because the detection efficiency is extremely low, it is usually only possible to use spot checks, and it is impossible to fully detect the possible defects in each steel pipe. In international bidding activities, steel pipe manufacturers participating in the bidding are usually required to have relatively complete detection measures. Although some companies have spent huge amounts of money to introduce some automatic detection equipment from abroad, due to the limitations of domestic production and testing supporting conditions, their use effect is often not ideal, resulting in many imported equipment being idle, wasting a lot of money. The current situation has greatly limited the international competitiveness of domestic steel pipe manufacturers.

Spiral steel pipe is a kind of steel pipe mainly used in fluid conveying pipelines because of its mature manufacturing process and low cost. At present, continuous forming and submerged arc welding are widely used to manufacture spiral steel pipes. There are two forming methods: internal support type and external support type. Since these two forming methods are generally insufficient forming, there is a large residual stress after the steel pipe is manufactured, which reduces the pressure-bearing capacity of the steel pipe. After theoretical analysis, the residual stress calculation formula of the steel pipe during insufficient forming is given, and the residual stress of the spiral steel pipe formed by internal support type is measured to verify the correctness of the residual stress calculation formula given in this paper, which has a guiding role in the manufacture and application of spiral steel pipes.

Nondestructive testing of steel pipe welds has always been an important problem that is difficult to solve and urgently needs to be solved by various enterprises. It is urgent to develop automated weld detection equipment suitable for my country's production conditions. Different ultrasonic methods are used for steel pipe flaw detection, and their flaw detection accuracy varies greatly. Due to the differences in the geometric shapes of the welds and the uncertainty formed by various composite defects, the difficulty of ultrasonic automated flaw detection of steel pipes is relatively large, and the influence of human factors is also large. How to improve the effectiveness and reliability of flaw detection results has become the focus of ultrasonic automated flaw detection of steel pipes. After investigation and research and years of experience in steel pipe flaw detection, a fully digital ultrasonic flaw detection system was developed that integrates a precise probe tracking system, single chip microcomputer technology, and computer signal processing functions in the spiral state of steel pipe. Compared with traditional flaw detectors, the spiral steel pipe digital online ultrasonic automatic flaw detection system has the following advantages:
(1) Fast detection speed, automatic detection, calculation, recording, automatic depth compensation, and automatic sensitivity setting.
(2) High detection accuracy, the system performs high-speed data acquisition, quantification, calculation, and discrimination of analog signals, and its detection accuracy can be higher than the detection results of traditional instruments.
(3) Record and archive detection, digital ultrasonic flaw detectors can provide detection records and even defect images.
(4) High reliability and good stability, can comprehensively and objectively collect and store data, perform real-time or post-processing on the collected data, perform time domain, frequency domain, or image analysis on the signal, and can also grade the workpiece quality through pattern recognition, reducing the influence of human factors and improving the reliability and stability of retrieval.
(5) The CCD camera tracking sensor is used for weld tracking, which has the advantages of high detection sensitivity, no fear of water, no fear of gas, and simplicity and reliability.

Spiral welded steel pipes are widely used in petrochemical, thermal pipe networks, and urban water supply and drainage engineering, especially in long-distance oil and natural gas pipelines. Almost all oil field and gas field pipelines use spiral welded steel pipes, which have high safety, durability, and economic rationality. Since the diameter of spiral welded steel pipes is generally not limited by the width of the plate, it can be made of a variety of different specifications of plates.
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