DTE GAS COMPANY — Integrity Assurance Notification

ASSUMED TOUGHNESSThe purpose of this letter is to provide notification, in accordance with §192.18 [1], of DTE Energy (“DTE”) intent to use other appropriate, conservative toughness values, in addition to the Charpy v-notch (CVN) toughness values prescribed in §192.712(e)(2)(i)(A)-(D), when performing Predicted Failure Pressure (PFP) analysis of cracks and crack-like defects as required under §192.712(d). DTE’s use of the other, conservative toughness values will provide an equal, or improved, level of pipeline safety compared to the CVN toughness values prescribed in §192.712(e)(2)(i)(A)-(D). This notification is being submitted based on consultation with DTE’s fracture mechanics experts at Structural Integrity Associates, Inc., and is consistent with industry best practices.#