Mechanical Engineer's Pocket Book, 3rd Edition

4.1.38 ISO Pipe threads, tapered: basic sizes

Terms relating to taper pipe threads

ISO pipe threads, tapered: basic sizes (see Tables 1 and 2).

Table 1

Nominal (bore) size of pipe a		Number of threads per inch	Pitch of thread (mm)	Depth of thread (mm)	Basic diameters at gauge plane
in.	mm	Major (gauge) diameter (mm)	Pitch (effective) diameter (mm)	Minor diameter (mm)
$\frac{1}{8}$	6	28	0.907	0.581	9.728	9.147	8.566
$\frac{1}{4}$	8	19	1.337	0.856	13.157	12.301	11.445
$\frac{3}{8}$	10	19	1.337	0.856	16.662	15.806	14.950 ...