Adopting the idea of double tension test developed at University of Tokyo, the author investigated the behaviours of steel plates to propagation of brittle crack under the similar condition to the service. Critical temperatures for crack propagation defined on the double tension transition curves by the same stress level as the design stress were found to be closely correlated to the 50 %crystallinity transition temperatures of the pressed-notch Charpy test. Acceptance criterion on the pressed-notch Charpy specimen derived systematically from the present experiments was well corresponding to the minimum Charpy requirements by the Lloyd's Register of Shipping and the Nippon Kaiji Kyokai, for the hull structural steel plates.