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21. Taps for Pipe Threads


Description of products
1. JIS Pipe Taps
The pipe thread standard (JIS B 0202,0203) was revised in 1982 to meet ISO standard. In the same year, JIS B 4445 (straight pipe thread taps) and JIS B
4446 (taper pipe thread taps) were also revised.
A part of the pipe thread standard was revised in 1966 to meet ISO, but in the 1982 revision, the ISO standard was defined in the main book of JIS and
the old 1966 standard was defined in JIS Appendix. For Pipe Threads specified in the main book of JIS and JIS Appendix, thread symbols are different
but the nominal size 1/8 to 6 inch are same. In the 1998 revision, the contents of the main book of JIS and JIS Appendix are not changed.
ISO tap standard for pipe threads is different from the JIS tap standard in style, size and thread limit. Like the pipe thread standard, in JIS tap
standards for pipe threads, style, size and thread limits of ISO standard are adopted in the main book of JIS and those of old JIS standard are in the
JIS Appendix. For ISO standard (style and size), please refer to the next page.
Thread limits of Rp and G taps are the same as the ISO standard. The thread limit of Rc taps is the same as the JIS class 2 of PT taps shown in JIS
Appendix because Rc is not specified in the ISO standard. Therefore, both Rc taps and PT taps can be used interchangeably. For the relation
between thread limit of internal threads and tap thread limit, please refer to the table below.
Pipe Tap standard was revised in 1987. And tap designations shown in JIS Appendix were changed to PF taps for Parallel Pipe Thread, PT taps for
Taper Pipe Thread, and PS taps for Parallel Pipe Thread.

■Symbol of Pipe threads

Type Classification Standard JIS (ISO) JIS Appendix Type
Internal Thread
Taper Thread
External Thread
Taper Thread
Internal Thread
Parallel Thread
External Thread
PF, A class
Internal Thread
PF, B class
Parallel Thread Parallel Thread
G, A class PF, A class
External Thread
G, B class PF, B class


■Relation between classification/engagement of pipe threads and taps
■
Kind of Classification Main usage type Engagement Pipe taps
thread
Parallel PS
Parallel internal thread
PS
D


（Rp）
D2


'
D1


Basic diameter position
Internal
In connection of pips, pipe Taper internal thread
D


threads PT
D2


Taper parts and fluid parts they Taper
D1


pipe are used mainly for the PT
threads purpose of pressure type （Rc）
Taper internal thread
D


joints.
D2
D1


t
Pipe thread
a f S-PT
Taper
External
PT
threads Taper external thread
（R）
d2
d1
d


Information
Technical


Internal PF Parallel internal thread
In connection of pipes, pipe PF
threads （G）
D


Parallel parts and fluid parts, they
D2
D1


pipe are used mainly for the
threads purpose of mechanical type
External PF
d
d2


joints. Parallel external thread
（G）
d1


threads

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