API RP 2Z:2005 pdf download

API RP 2Z:2005 pdf download.Recommended Practice for Preproduction Qualification for Steel Plates for Offshore Structures.
3.6 COMMENTARY
Four HAZ regions are defined in the bead-on-plate weld cross section shown in Figure 2. If a second pass is placed as shown in
Figure 3a, then some of the first-pass HAZ regions are eliminated, while others are significantly altered. Figure 3b shows Figure
3a with some of the altered and unaltered regions identiticd.
3.6.1 In a multi-pass weld with one plate edge unbeveled. the overlapping llAZs that penetrate the unbeveled edge appear as shown in Figure 4a. Columnar weld metal is also identified in this figure and includes weld metal that has not been atTected by the heat of subsequent passes and weld metal that has been sub-critically reheated (i.e., a SCHAZ in weld metal). Because this weld metal is relatively unaffected, it still displays a columnar structure when etched. Weld metal that has been inter-critically or super-critically reheated (i.e., above the Al or A3 temperatures, respectively) does not display a perfectly columnar structure when etched. The weld metal HA7.s are shown in Figure 4 and the portions that have been heated above the A I are shaded and contain broken columnar lines. Redrawing Figure 4a so that only unaltered (‘CiHAZ areas are depicted results in Figure 4h. Redrawing Figure 4b to include the IRCG and the SRCG results in Figure 4c. Notice that the unaltered (GHAZ and SRCG are directly adjacent to the fusion line where the unrefined columnar weld metal contacts the base metal. The approximate position of the CG regions of interest for fatigue crack sampling can be determined using the following procedure: (I) draw arcs along the fusion line only directly adjacent to the regions of unrefined columnar weld mcta, (2) draw a second set of arcs parallel to the first set, but 0.5 mm (0.02 in.) away on the base metal side (0.3 mm (0.0 12 in.) for the lowest heat input weld). The regions between the two sets of ares contain the unaltered CGI-f AZ and the SRCG. The IRCG lies directly adjacent to the SRCG (sec Figure 4c).
Figure 4d highlights the “etched HAZ boundary material”. Notice that the etched HAZ boundary is the outer line of the visible etches HAZ and lies between ICHAZ and S(’HAZ. The etched [IAZ boundary material is defined as follows: draw a line along the visible etched HAZ boundary; draw another line parallel to the first, but 0.5 mm (0.02 in.) away on the base metal side (0.3 mm (0.012 in.J for the lowest heat input weld). The region between the two lines is the etched HAZ boundary material. Notice that the etched I-IAZ contains the ICHAZ.
3.6.2 The futiguc crack in the “CGHAZ” C1’OD specimen should be placed where ii will sample the maximum amount of the unaltered CGHAZ, the IRCG and the SRCG (Figure 4c). When conducting an “etched HAZ boundary material” CTOD test, the futigue crack should be placed where it will sample the maximum amount of the unaltered SCI-IAZ (Figure 4d). To properly define the unaltered CGHAZ microstructure for any weld, the HAZ microstructure adjacent to the square-edge fusion line of each test specimen should be visually inspected using an optical microscope at magnifications of 5X and lox. This inspection should be completed in sections 3.6.4 and 3.6.5. The relative grain size and the width of unaltered CGHAZ regions should be established for each specimen. Unaltered CGHAZ regions should be identified as the regions having the largest observable grain sizes which are located along the fusion line adjacent to unrefined columnar weld metal. The visual inspection that defines the unaltered CGHAZ regions intended to be sampled for those specimens to be notched.