scope:

FOREWORD

These specifications were prepared by the A.P.I.Committee on the Standardization of Rotary Drilling Equipment. and are the result of a 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 4¹/₂ X 5¹/₂-4 joints were originalll' 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 dimeneions ahown In Table 2 were based uPon pitch diameters one inch from gage nep of 5.69530" and 5.1402'1" respectivell'. fumished by the Union Tool Company.

(c) The '7 x 8 - 4 joint was designed by the E. M. Smith Companl'. LOB Angeles. Califomla, and has been in actual service for a considerable length of time. for ule with 8⁵/₈ O. D. or similar lized 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 4.0266", furnished by the E. M. Smith Companl'.

(d) Standards on 7⁵/₈ and 85/8 inch drill pipe have been adopted tentatively. and are Included in the Sixth Edition of the A.P.I. Pipe Specifications. A. P. I. Stds. No.6-A. The Rotary Drilling Equipment Committee is now considering the preparation of standards for  7⁵/₈ lnch rotary tool joints.

(f) In all cases in computing thread height and truncation, account bas been taken of the effect of taper in reducing thread beight 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, 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 65/8 drill pipe and will be identified and marked as 65/8 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.