Study Of Ultra High Pressure Vessels And Piping The Weeks To Ultrasonic Testing

As high-risk apparatus, ultra-high pressure vessel and pipes are widely used in ethylene polymerization, synthesis of manmade quartz and diamond, static pressure treating, ultra-high static pressure extruding, powder metallurgy, metal forming, geophysical and geomechanics research. At present, most of the ultra-high pressure vessels and pipes are monobloc thick-wall cylinder, during whose manufacture and in-service process, non-destructive test is a reliable method to make sure its quality and safe service. As Ultrasonic Test (UT) is capable to test apparatus inside and outside as well, it becomes the main test way for ultra-high pressure vessels and pipes, yet circumferential UT is hard to perform on them, especially when the ratio of inner radius to outer radius small than 0.6. Meanwhile, there are few mature technique and existing standard domestic and abroad. Basic on the deep analysis of state-of-the-art domestic and abroad, this paper systematically investigated the circumferential UT for ultra-high pressure vessels and pipes. The main work and research results are as follows:1) Based on the analysis of structure of sound field, echo characteristic of radial defects, echo depth of inner face defect, defect locating, self height identified method and ultrasonic coupled wave theory in curved face, the criterion for close incident critical angle of angle beam probe, defect locating method, self height identified method, testing sensitivity and characteristic parameter of the probe were brought up, according to which, a close incident critical angle shear wave technology and circumferential UT methods for cylinder with different specification were formed.2) Confirmed by experiments comparison that close incident critical angle shear wave method which brought forward in this paper has sufficient SNR and locating accuracy forcylinders with r/R≥0.56, which broke through the conventional theory that shear wave can only used for cylinders with r/R≥ 0.6 .The testing reliability of double wave modestechnique, modified SW corner-echo technique for cylinders with r/R < 0.56 was alsoconfirmed by sensitivity comparison experiments.3) Combined with testing of artificial defect and real defect and in filed applications ofultra-high synthetic crystal vessels and ultra-high ethylene carrier pipe, confirmed the accuracy and feasibility of the technology method and parameter that put forward in this paper.