GRI (Gas Research Institute) Research Program on the Crack-Arrest Properties of 9% Nickel Cryogenic Steels

摘要

Despite the excellent safety record of LNG storage tanks fabricated from 9% nickel steels, questions were raised whether adequate testing had been conducted to ensure that a running crack would be arrested. Consequently, the Gas Research Institute and 13 European, Japanese, and U.S. organizations, sponsored an experimental and analytical research program to examine the performance of 9% nickel steels and their welds under LNG storage tank conditions. The research showed that (1) the welded joints do not seriously detract from the ability of 9% nickel steel to arrest a propagating crack, (2) useful correlations can be derived among various crack arrest tests and other notch toughness tests, (3) the dynamic factors affecting crack arrest are relatively small, and (4) present production heats of 9% nickel steel exhibit enhanced fracture toughness well above minimum standards, largely due to reduced carbon and impurity levels.