During the August 2018 ASME Committee Week, a Code Change Inquiry was presented to the Working Group on Operating Plant Criteria (WGOPC):
Question 1: Is it the intent of G-2110 to limit RTT0 use to ferritic materials with specified minimum room temperature yield strengths 50 ksi or less?
Question 2: If the reply to Question 1 is “No”, is it the intent of G-2110 that G-2110(b) requirement must be met before RTT0 may be used for ferritic materials above 50 ksi but not exceeding 90 ksi?
During that meeting the WGOPC replied “no” to both questions. This paper provides an evaluation of available fracture toughness data augmented by an understanding of the underlying mechanisms of cleavage fracture to demonstrate the veracity of the WGOPC’s answer with regards to RTT0 and, more generally, with respect to the Master Curve.