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This standard replaces GB/T12716-2002 "60° Sealed Pipe Thread". Compared with GB/T12716-2002, the main technical changes of this standard are:

--- Adjust the tolerance values of the top and bottom heights of some threads (Table 1);

--- Adjust the reference distance of part of the thread and the value of the assembly allowance (table 2);

--- Adjust the maximum pitch diameter of some cylindrical internal threads (Table 4);

--- Add thread inspection chapter (Chapter 11) and thread gauge (Appendix A);

--- The new standard deletes Appendix A of the old standard (the inch size table of pipe threads).

This standard adopts the redrafting method to modify and adopt the American standard ASMEB1.20.2M:2006 "General Purpose Pipe Thread". Compared with the U.S. standard, my country's standards are mainly different as follows:

--- Thread size code: The United States uses Dx, Ex, Kx, p, D and d to represent the major diameter, intermediate diameter, minor diameter and pitch of the thread, and the outer and inner diameter of the pipe; while my country and ISO use D, D2 , D1, d, d2, d1 and P represent the major diameter, middle diameter and

The minor diameter, the major diameter, the middle diameter and the minor diameter of the external thread, and the thread pitch. In order to avoid conflicts with the existing thread code system of my country and ISO, this standard does not use the part of the US size code that conflicts with my country.

———In the thread marking, the American standard firstly gives the thread size code, and then gives the thread feature code; while in my country's thread standard system, the thread feature code is first marked, and then the thread size code is marked. In addition, in order to simplify the thread marking, the Chinese standard allows the omission of the number of threads in the thread marking.

———GB/T14791 is cited in the normative references