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

Using a multimeter to measure the electrode contact resistance when full of liquid is a convenient method to judge the condition of the pipe wall, although it is only to determine the general value. For accurate measurement, AC bridge must be used, such as "Kohlraush bridge".