2. Test results CTOD test system and weld CTOD sample after loading test. In the test, there are pop in HAZ samples, 8 effective samples in weld zone and 8 effective samples in HAZ, which meet the requirements of CTOD multi sample method. Wherein, the CTOD value of HAZ crack initiation point accounts for; C Critical CTOD value obtained by direct measurement= 0.05 Use the intersection point of multiple sample CTOD test regression line and crack growth 0.05mm vertical line to determine the CTOD value of the protrusion point; M is measured directly by the test. CTOD value of weld crack initiation point; C and critical CTOD value= 0.05 Determine the CTOD value of the protrusion point by the intersection of the regression line of the CTOD test of multiple samples and the vertical lines of the crack growth amount of 0.00mm and 0.05mm; M is measured directly from the test. See Table 1 for CTOD calculation results of welds and HAZ. Table 1 CTOD test results; c/ mm ; c/ mm ; C/mm heat affected zone 0.1970.240.53 weld 0.1960.230.91

1、 The cause of the fault is that the zero point is unstable. The human body can be summarized into five fault causes, which are:
(1) The pipeline is not full of liquid or the liquid contains bubbles;
(2) Subjectively, it is considered that the liquid in the pipeline system has no flow but actually has small flow; In fact, it is not enough for the electromagnetic flowmeter to fail, but it is enough to accurately reflect the misunderstanding of flow conditions;
(3) The sensor grounding is not perfect and is subject to external interference such as stray current:
(4) Reasons for liquid (such as liquid conductivity uniformity, electrode pollution, etc.);
(5) The insulation of signal circuit drops.