FOREWORD (a) These specifications were prepared by the A.P.I. Committee on the Standardization of Rotary Drilling Equipment. (b) Include herein are complete dimensional standards for eight of "regular" and five sizes of "full-hole" rotary drilling taper joints, prepared after intensive investigations and field trials. These joints are identified as to "size" by the size of the drill pipe on which used. For example the outer (drill pipe) ends of the "regular" rotary taper joint having nominal pin dimensions of 5"X6" , and of the "full-hole" joint having nominal pin dimensions of 51/15/6X6 3/4 4, are both threaded to fit 65/8 A.P.I. standard internal-upset drill pipe, and are therefore known as 65/8 inch rotary taper joints. The letters "FH" are used to identify the full-hole tool joints. These specifications also include standards on drill collars, grief stems, fishtail bits, rotary hose, piston rods of slush pumps, brake bands, center, distance on rotary table, and certain "recommended practices" in measurement. (c) While these specifications are intended to include sufficient dimensions to insure interchangeability, especially as regards threaded connections, many dimensions not essential to interchangeability, such as length of drill collars, are omitted, and when purchasers have preference on such unlisted dimensions, the purchase order should so state. In any case, in order to avoid misunderstanding and. delay, purchasers should . signify the type of thread desired, i.e., whether "regular" or "full-hole", as well as the size. In many cases optional lengths and/or diameters are indicated which are obtainable on specificial order. In such cases the "standard" length, diameter, or style of thread will be furnished unless the purchaser specifically requests otherwise. The intent of the specification is to permit the use of the monogram on equipment which is interchangeable, and still enable the manufacturer to supply, or the purchaser to obtain, this equipment with other details, not affecting interchangeability, in accordance with usage or specified order. (d) These specifications provide for the use of the A.P.I. monogram on certain material; on other material covered by these specifications the monogram is not permitted. The monogram can be used only by licensees who have been so authorized by the Institute, and its use on material is a guarantee from the manufacturer to the user that the material so marked complies with the specification. Purchasers are urged to inspect material to verify that it is properly marked, and that it meets the specification. Material which is not properly marked, or does not meet the specification, should be rejected, (See Section XIV). (e) Manufacturers desiring to use the monogram on material covered by this specification, should apply for and obtain that right (see Appendix D). In addition, the licensee must have in his possession certified gages (when specified. as for both regular and :fall-hole tool joints, this including drill pipe gages, which are required for checking the drill pipe threads in the outer ends of both regular and full. hole tool joints). Licensees must familiarize them selves with all gage stipulations, and should follow the Committee's recommendations on care of gages. (Appendices A and B). Gages must be tested periodically and report made thereon to the Institute (Section XVI). (f) The Committee will welcome comments on these specifications