scope:

FOREWORD

(a) These specifications were prepared by the Special A. P. I. Committee on the Standardization of Rotary Drilling Equipment, and are the result of extensive investigations embracing a period of over three years. Comprehensive field teats were made on various types before finally deciding on the joints specified herein.

(b) The 5 x 6 - 4 and 4½ x 5½ - 4 joints were originally designed by the Union Tool Company. Torrance. California, and have been in actual use for many years in all the oil fields of the United States and abroad. The gage dimensions shown in Table 2 were based upon pitch diameters one inch from gage step of 5.69530" and 5.14027" respectively, furnished by the Union Tool Company.

(c) The 7 x 8 - 4 joint was designed by the E. M. Smith Company, Loa Angeles, California, and has been in actual service for a considerable length of time, for use with 8⁵/₈" O. D. or similar sized drill pipe. The dimensions shown in Table 2 were based upon radial measurements of pitch diameter over wire, 0.200" diameter, at ⁵/₈" step, equal to 4.0256", furnished by the E. M. Smith Company.

(d) It should be noted that the American Petroleum Institute has not officially adopted any drill pipe larger in size than 6 ⁵/₈" O. D. However, due to the occasional use of 8 ⁵/₈" and similar sized drill pipe, it was considered desirable to set up a standard taper joint for use therewith. It should be borne in mind, therefore, that variations may exist in the pipe ends of rotary tool joints in this size, and the purchaser should specify the size and threads desired to fit his drill pipe In the 8 ⁵/₈" O D. or similar sizes.

(e) The other sizes of taper joints contained herein are new, and were developed by the Committee. These other sizes, however, so closely approximate sizes and threads now in general use, that specific field tests were considered, unnecessary. The dimensions given in Table 2 on the first 4 sizes were based upon Diameter "A" at small end, as given in Table 1.

(f) In all cases in computing thread height and truncation, account has been taken of the effect of taper in reducing thread height for a given pitch, as compared with values for the same pitch on a cylinder.

(g) The thread specified herein conforms to the National Form of Thread, except as to truncation of crests and roots, which is definitely specified.

(h) Particular attention is directed to the method adopted herein for identifying Rotary Drilling Taper Joints, viz: the taper joint is known by the size drill pipe with which tool joints must be used. For example the 5 x 6 - 4 rotary tool joint is used with 6 ⁵/₈" drill pipe and will be identified and marked as 6 ⁵/₈" joint. In order to identify the joints in the tables of drill collars, fishtail bits, couplings, etc, the size drill pipe is listed with the nominal size of taper joint. However, this does not prevent the taper joints, being used in any combination desired for drill collars and fishtail bits.