scope:

FOREWORD:

This specification was prepared by the API Committee on the Standardization of Cable Drilling Tools. The standards on taper joints are based on the I. & H. (Ireland and Hughes) standards that have been in common use in the oil country for twenty-five years and generally known as "Eastern Specifications." While the majority of manufacturers had their own master gages, there were no national master gages available for general checking purposes except the original set of soft I. & H. gages owned by the Oil Well Supply Company, Pittsburgh, Pa.

The Committee, after deciding on the standard sizes specified herein, requested the Pratt & Whitney Company to make up a hardened and ground master gage in the 3¾%, size, accurately manufactured to close tolerances. A special sub-committee visited the plants of the principal cable tool manufacturers and compared their master gages with this specially-made sample gage. A considerable variation was found between the gages of the various manufacturers and his sample gage. It was therefore decided by the Committee to establish uniform master gages for all sizes of joints.

A large group order was assembled among the principal manufacturers and consumers, which was placed with Pratt & Whitney with the understanding that the gage in each size found to be nearest to the theoretically perfect should be selected as the grand master and become the property of the American Petroleum Institute; these grand masters to be deposited with the National Bureau of Standards in Washington, to be used only in case of dispute. Three additional sets of gages to be selected as being the nearest to the Grand Master; to be known as Special Reference Master Gages to be owned by the American Petroleum Institute and deposited with custodians in the Eastern, Mid-Continent and Pacific Coast Districts, so that the manufacturers and consumers in these districts could check their gages at suitable intervals and maintain them up to standard.