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Tapered Pipe Threads (Excerpt from JIS B 0203:1999)

Standard profile
Standard dimensions

Standard profile

Standard profiles applied to tapered male threads and tapered female threads

Standard profile applied to parallel female thread

Tapered male thread fitting with tapered female thread and parallel female thread

Standard dimensions

Nominal thread size ⁽¹⁾	Screw thread				Standard diameter			Standard diameter position			Tolerance of D, D2, and D1 in parallel female threads	Length of effective thread section (minimum)				Dimensions of carbon steel pipe (reference)
	Number of screw threads (number per 25.4 mm)	Pitch p (reference)	Thread height h	Roundness r or r'	Male thread			Male thread		Female thread		Male thread	Female thread
					Male thread			Male thread		Female thread		Length toward the large diameter side from the standard diameter position f	With an incomplete thread section		Without an incomplete thread section
					Outer diameter d	Effective diameter d2	Valley diameter d1	From pipe end		Pipe end			With an incomplete thread section		Without an incomplete thread section
					Outer diameter d	Effective diameter d2	Valley diameter d1	From pipe end		Pipe end			Tapered female thread	Parallel female thread	Tapered female thread and parallel female thread
					Female thread			Standard length a	Tolerance in the shaft line direction b	Tolerance in the shaft line direction c			Tapered female thread	Parallel female thread	Tapered female thread and parallel female thread
					Valley diameter D	Effective diameter D2	Inner diameter D1	Standard length a	Tolerance in the shaft line direction b	Tolerance in the shaft line direction c			Length toward the small diameter side from standard diameter position ℓ	Length from pipe or pipe fitting end ℓ'(reference)	t⁽²⁾	Outer diameter	Thickness
R1/16	28	0.9071	0.581	0.12	7.723	7.142	6.561	3.97	±0.91	±1.13	±0.071	2.5	6.2	7.4	4.4	－	－
R1/8	28	0.9071	0.581	0.12	9.728	9.147	8.566	3.97	±0.91	±1.13	±0.071	2.5	6.2	7.4	4.4	10.5	2.0
R1/4	19	1.3368	0.856	0.18	13.157	12.301	11.445	6.01	±1.34	±1.67	±0.104	3.7	9.4	11	6.7	13.8	2.3

R3/8	19	1.3368	0.856	0.18	16.662	15.806	14.95	6.35	±1.34	±1.67	±0.104	3.7	9.7	11.4	7	17.3	2.3
R1/2	14	1.8143	1.162	0.25	20.955	19.793	18.631	8.16	±1.81	±2.27	±0.142	5	12.7	15	9.1	21.7	2.8
R3/4	14	1.8143	1.162	0.25	26.441	25.279	24.117	9.53	±1.81	±2.27	±0.142	5	14.1	16.3	10.2	27.2	2.8

R1	11	2.3091	1.479	0.32	33.249	31.77	30.291	10.39	±2.31	±2.89	±0.181	6.4	16.2	19.1	11.6	34	3.2
R1 1/4	11	2.3091	1.479	0.32	41.91	40.431	38.952	12.7	±2.31	±2.89	±0.181	6.4	18.5	21.4	13.4	42.7	3.5
R1 1/2	11	2.3091	1.479	0.32	47.803	46.324	44.845	12.7	±2.31	±2.89	±0.181	6.4	18.5	21.4	13.4	48.6	3.5

R2	11	2.3091	1.479	0.32	59.614	58.135	56.656	15.88	±2.31	±2.89	±0.181	7.5	22.8	25.7	16.9	60.5	3.8
R2 1/2	11	2.3091	1.479	0.32	75.184	73.705	72.226	17.46	±3.46	±3.46	±0.216	9.2	26.7	30.1	18.6	76.3	4.2
R3	11	2.3091	1.479	0.32	87.884	86.405	84.926	20.64	±3.46	±3.46	±0.216	9.2	29.8	33.3	21.1	89.1	4.2

Notes

(1) This nominal thread size is for tapered male threads. For tapered female threads and parallel female threads, replace the R symbol with Rc or Rp (refer to *).
(2) For tapered male threads, this is the length toward the small diameter side from the standard diameter position. For tapered female threads, this is the length from the pipe or pipe fitting end.

Remarks

1. The screw thread is at a right angle to the central shaft line, and the pitch is measured along the central shaft line.
2. The effective length of the thread section is the length of the completely-cut thread section. The surface of pipe or pipe fitting may remain on the last several threads.
Besides, even if the end of the pipe or pipe fitting is chamfered, this section is included in the effective thread section length.
3. If it is difficult to use this table for values a, f, and t, refer to separately established component standards.
*Tapered pipe threads include male tapered pipe threads, female tapered pipe threads, and female parallel pipe threads.
This parallel pipe thread is to be used with male tapered pipe threads, and the dimensional tolerance is different from that of the parallel pipe thread regulated in JIS B 0202.