API 934F Task Group – Discussion Items Based on Comments Received on Initial Rough Draft

1. API 934F Task Group – Discussion Items Based on Comments Received on Initial Rough Draft API 934F Task Group Meeting September 23, 2014, Alexandria, VA Jim McLaughlin Editor, API RP-934F

2. Discussion Items • Starting point temperature for fast fracture considerations based on temper embrittlement considerations • Guidance based on industry experience and Charpy 40 ft-lb transition temperature • It is noted Charpy data indicates higher 40 ft-lb transition temperature for some specific examples compared with guidance on starting point temperature • Specific examples typically included welds that would not be considered limiting in an assessment – circumferential and pad support welds • Data of concern – one case where base plate had a transition temperature about 400°F • Use of curve for a hydrogen concentration ratio of 1.54 for Level 2 assessment procedure – Is it conservative enough to address most likely crack geometries to be encountered in a reactor vessel? • Hydrogen concentration ratio is 0.92 for compact tension test samples • Similar but less deep crack geometries expected in reactor vessels

3. Discussion Items (continued) • Temperature dependence of HEAC in 2¼-1Mo-V steel • Summary/continuation of Dr. Nibur discussion • Additional funding for HEAC testing at higher temperatures • J-factor for high impurity tested plate is 312 and X-bar for high impurity tested weldments is 25 • Current industry chemistry control is J-factor 100 or less and X-bar 12 or less • See plot for typical heats before chemistry control employed – several heats have J-factor above 312 • Growth of embedded crack-like flaws • Industry experience and 2 sets of testing show that embedded crack-like flaws do not grow • Draft document concludes that growth of embedded crack-like flaws is a non-credible event • Is this conclusion supported by the Task Group?

4. J-factor for Typical Heats without Chemistry Control J-factor for tested plate

5. Discussion Items (continued) • Should the document include more information on Dr. Anderson’s approach to hydrogen assisted slow stable crack growth • Present plan is to include this approach as an example of a Level 3 MPT assessment • Other discussion items • Next steps for API 934F document • Include Level 3 examples into the document • Include Appendices into the document • Appendix C needs to be written • Continue to include comments/corrections as received into document • Before Spring 2015 meeting have document edited by Mary Buchheim