This Specification covers various grades of high-test line pipe. The proper grade designations to be used under this specification comprise the letter X followed by the first two digits of the specified minimum yield strength. Thus X 42 designates the grade having specified minimum yield strength of 42@000 psi; x52@ 5200 psi@ etc. Complete requirements are specified for the X 42 grade only@ these including processes of manufacture@ chemical and physical requirements@ methods of test@ dimensions on diameter@ thickness@ length@ etc. Higher strength grades available under this specification are subject to agreement between the purchasers and the manufacture as to chemical@ tensile and flattening test requirements as given herein Nothing contained in this specification in to be construed as granting any right@ by implication or otherwise@ for manufacture@ sale@ or use in connection with any method@ apparatus@ or product covered by letters patent. Nor as insuring anyone again liability for infringement of letters patent.