scope:

This specification covers dimensional requirements on threads and thread gages and stipulations on gaging practice, gage specifications and certification as well as the instruments and methods for the inspection of threads for line pipe, round-thread casing and tubing, buttress casing and extreme-line casing joints. It is applicable when so stipulated in the API standard governing the product. The inspection procedures for measurements of taper, lead, height, and angle of thread are applicable only to threads having 11 '¹/₂ or less turns per inch.

Thread inspection applies at the point of manufacture prior to shipment, to inspection at any intermediate point, to inspection subsequent to delivery at destination, and to inspection by inspectors representing the purchaser or the manufacturer. The manufacturer may, at his option, use other instruments or methods to control manufacturing operations; but acceptance and rejection of the product shall be governed solely by the results of inspection made in accordance with the requirements of this specification.

Policy. American Petroleum institute (API) specifications are published as an aid to 12r.!JCUJ'ement of standardized equipment and materials. These specifications are not intended to inhibit purchasers and producers from purchasing or producing products made to specifications other than API, and nothing in any API specification is intended to in ,way inhibit the purchase of products from companies not authorized to use the API monogram.

Nothing contained in any API specification is to be construed as granting any right, by implication or otherwise, for the manufacture, sale, or use in connection with any method. Apparatus or product covered by letters patent, nor as insuring anyone against liability for infringement of letters paten