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 11½% or less turns per inch. All thread dimensions shown without tolerances are related to the basis for joint design and are not subject to measurement to determine acceptance or rejection of product.

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.

Although this specification contains complete dimensional information for threading and gaging buttress and extreme-line casing joints, considerable skill and know-how is required for the tooling for, and machining of, these joints. Therefore, any manufacturer who desires to produce these joints is advised to consult with manufacturers who have produced these joints before attempting their manufacture.

American Petroleum Institute (API) Specifications are published as aids to the procurement of standardized equipment and materials. as well as instructions to API Licensees. These Specifications are not intended to obviate the need for sound engineering, nor to inhibit in any way anyone from purchasing or producing products to other specifications.

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 patent.

API specifications may be used by anyone desiring to do so, and every effort has been made by the Institute to assure the accuracy and reliability of the data contained in them. However, the Institute makes no representation, warranty, or guarantee in connection with the publication of any API specification and hereby expressly disclaims any liability or responsibility for loss or damage resulting from their use, for any violation of any federal, state or municipal regulation with which an API specification may conflict, or for the infringement of any patent resulting from the use of an API specification.

Any manufacturer producing equipment or materials intended to conform to an API Specification is responsible for complying with all the provisions of that Specification. The American Petroleum Institute does not represent, warrant or guarantee that such products do in fact conform to the applicable API standard or specification.