This notice revokes a final rule that would require weekly monitoring of the water content of anhydrous ammonia transported by interstate pipeline. The purpose of the rule was to prevent failures caused by stress corrosion cracking. Where necessary, the rule required that water be added to anhydrous ammonia to at least the 0.2 percent level. Although the costs of the subject rule are practically nil and although a strong technical argument can be made in support of the rule, the MTB does not now have sufficient statistical data to clearly demonstrate that a-certain number of failures due to stress corrosion cracking will be prevented by allowing the rule to become effective.