Davis-Besse Small Bore Class 1 Piping Socket Weld Destructive Examination Authors: Ryan Hosler (AREVA) Beverly Cyrus (AREVA) Steve Fyfitch (AREVA); Presenter Trent Henline (FENOC)
Introduction Davis-Besse LRA includes a requirement to volumetrically or destructively examine (DE) welds (that have been exempted due to size by ASME XI) as a result of age-related OE Weld selection was based on SCC susceptibility Highest temperature Dead legs (stagnant) DE was selected because each DE counts as two NDE in the LR AMP 42 of the most susceptible welds were being removed due to SG replacement 15 of those welds were chosen as a representative sample to satisfy the LR AMP requirements for socket welds Steve Fyfitch August 2016 - p.3
Locations Examined: SG Channel Head Drain Lines SG 1-1 Drain Line SG 1-2 Drain Line Steve Fyfitch August 2016 - p.4
Locations Examined: Hot Leg High Point Vent Lines HL HPV Lines at SG 1-1 HL HPV Lines at SG 1-2 Steve Fyfitch August 2016 - p.5
General Sectioning Plan Mount/Polish/Etch 0 Face Mount/Polish/Etch 90 Face Mount/Polish/Etch 270 Face Mount/Polish/Etch 180 Face Steve Fyfitch August 2016 - p.6
Weld Socket Weld Gap Gap Steve Fyfitch August 2016 - p.7
0 Face SG 1-1 Drain Line Weld 7 8x 900x 180 Face 8x 50x Steve Fyfitch August 2016 - p.8
SG 1-1 Drain Line Weld 8 (270 Face of 8-A2) 8x Steve Fyfitch August 2016 - p.9
SG 1-1 Drain Line Weld 8 (270 Face of 8-A2) 25x Steve Fyfitch August 2016 - p.10 1500x
SG 1-1 Drain Line Weld 8 (270 Face of 8-A1a) 8x Steve Fyfitch August 2016 - p.11
SG 1-1 Drain Line Weld 8 (270 Face of 8-A1a) 50x Steve Fyfitch August 2016 - p.12
SG 1-2 Drain Line Weld 23 8x Steve Fyfitch August 2016 - p.13
SG 1-2 Drain Line Weld 23 Steve Fyfitch August 2016 - p.14
SG 1-2 Drain Line Weld 24 (180 Face) 8x Steve Fyfitch August 2016 - p.15
SG 1-2 Drain Line Weld 24 (180 Face) 200x 8x 500x Steve Fyfitch August 2016 - p.16
SG 1-2 Drain Line Weld 24 (270 Face) 8x 8x Steve Fyfitch August 2016 - p.17
SG 1-2 Drain Line Weld 24 (270 Face) 500x 200x 8x 600x Steve Fyfitch August 2016 - p.18
SG 1-1 HL HPV Line Weld 3C 8x Steve Fyfitch August 2016 - p.19
SG 1-1 HL HPV Line Weld 3C 200x 1500x Steve Fyfitch August 2016 - p.20
1-5% TW 0.084 gap 40-65% TW 0.031 gap Summary of Results: SG Channel Head Drain Lines 40-50% TW 0.130 gap 20-35% TW 0.087 gap No Flaw 0.077 gap SG 1-1 Drain Line No Flaw 0.048 gap SG 1-2 Drain Line 1-5% OD 0.143 gap Steve Fyfitch August 2016 - p.21
No Flaw 0.065 gap No Flaw No gap Summary of Results: Hot Leg High Point Vent Lines No Flaw 0.032 gap 1-5% TW No gap No Flaw 0.048 gap HL HPV Lines at SG 1-1 No Flaw 0.145 gap No Flaw 0.126 gap No Flaw No gap HL HPV Lines at SG 1-2 Steve Fyfitch August 2016 - p.22
Conclusions Cracking originating at or near the weld root was observed in 5 of the 15 socket welds examined Flaws indicative of TGSCC with some IGSCC and IGA Three synergistic requirements of SCC met (consistent with laboratory testing and operating experience) Susceptible Material Austenitic stainless steel (Type 316 and 308/308L) Aggressive Environment Stagnant water can accumulate elevated levels of dissolved O 2 and Cl, which can be exacerbated at the weld root by the crevice created by the socket weld geometry Temperature likely >200 F at locations of indications due to proximity to SG/HL Sustained Tensile Stress Socket weld geometry creates a stress concentration at the weld root Steve Fyfitch August 2016 - p.23
Questions? Steve Fyfitch August 2016 - p.24