Quality testing for seamless pipe
Seamless steel pipe quality testing is a very important step, and for its detection method is also very particular to now all three - ultrasonic testing, eddy current testing, magnetic flux leakage testing, specific circumstances are as follows:
- For steel quality inspection, ultrasonic testing, including for the purpose of detected defects ultrasonic testing and ultrasound to measure the dimensions for the purpose of measuring. Wider application of the former, automated testing, manually testing; latter application, generally manual measurement.
- Nondestructive Testing, shorted for NDT, is a widely-used method in pipeline inspection. It is a process of testing, inspecting and evaluating the quality and characteristics of the material without damaging the pipeline itself or affecting the later regular work of the pipe. In other words, after NDT testing, the part can still be put into practical use. NDT utilizes the changes in heat, sound and magnets caused by abnormal inner structure or flaws to inspect the internal and external defects of the material.
- The common inspection methods of NDT are visual testing (VT), ultrasonic testing (UT), radiographic testing (RT), hydrostatic testing. Anson International co, ltd uses ultrasonic testing (UT) and hydrostatic testing to inspect its line pipes.
- In order to verify the mechanical properties of seamless steel pipe to meet the requirements of the standard, the test sample of seamless steel pipe mechanical performance should be prepared carefully. Mechanical property test includes tensile strength, yield strength, elongation, impact energy and so on. Process performance test includes flattening test, flaring test, hydrostatic testing, curling trials, cold bend test, perforation test. These test items are based on different standards and different uses of seamless steel tubes.
The magnetic flux leakage testing
- The magnetic flux leakage testing is a non-destructive testing technology based on ferromagnetic material magnetic changes. When the ferromagnetic material is magnetized, and generates a leakage magnetic field due to the presence of defects on the workpiece surface, and therefore, through the detection of the magnetic flux leakage can be found in defects in the large caliber Seamless thermal expansion material. Steel pipe magnetic flux leakage testing technology is divided into two kinds of magnetic particle inspection method and magnetic field measurement method.
- The former is simple, but requires the naked eye to observe the magnetic marks, it is difficult to automate. The latter despite the device complexity, high cost and the operation is difficult, but it is picked up by sensors leakage magnetic field information, and therefore easy to automate testing suitable for the automatic inspection of large quantities of steel pipe. Therefore, under normal circumstances, no special instructions, usually refers to the magnetic field of the magnetic flux leakage testing of steel pipes assay.
Eddy current testing
- Eddy current testing method is more wide range of applications in the industrial field of non-destructive testing methods. It is based on the theory of electromagnetic induction, without any coupling agent can 100% fast automatic detection of the specimen. it is even more powerful tool for the rapid detection of bulk. Therefore, it is even not limited to the large caliber thermal expansion seamless steel pipe, has become a necessary means of various types of steel quality inspection. Automatic eddy current testing method is mainly suitable for quality inspection of steel pipes a little probe testing method and through-probe testing method two.
- The former method of using the high-speed rotation of the point probe to detect longitudinal defects in the steel pipe, the detection speed is determined by the quantity of the probe and the speed of rotation, in general, is relatively slow, and the latter through the probe to detect the steel pipe transverse defects, this method is simple, and the testing speed (generally up to 60m/min), Further, since the eddy current flaw detection method is particularly sensitive pair of through holes, the related standards of the main method is to replace the pipe hydrostatic test.