4 reasonable hardness values for the base metal, HAZ and weld metal, where average hardness values of 181HV, 183HV and 179HV were obtained for base metal, HAZ and weld metal respectively (Table 2). The given hardness values are the average of five readings. Results of the tensile test for both base metal and welded joint of the failed spool are shown in Table 3. The given tensile values are the average of three specimens. Results of the impact test, at different temperatures, of the base and weld metals of the failed spool are shown in Table 4. The given impact values are the average of three specimens. Results of both tensile and impact tests showed normal values based on specified properties for the used material. The given hardness values are the average of five readings. Figure 4 Optical micrographs with high magnification of cross sections taken from zones 1 and 4 in Figure 1-b. Note normal austenitic microstructures for base metal, HAZ and weld metal. Cracks were propagated through grain boundaries. Figure 3 Macrographs of a cross section taken from zone 2 in Figure 1-b showing toe cracks propagated through thickness of 16" pipe. Table 2. Results of hardness measurements (HV) of fractured spool together with the specified value for ASME-SA213, 316L stainless steel.
RkJQdWJsaXNoZXIy MjM0NDE=