Test Codes – JIS Threads – RYCO Hydraulics

JIS Threads

JIS is JAPANESE INDUSTRIAL STANDARDS
There are four popular coupling styles in Japan

1. JIS Tapered Pipe Thread

The Japanese tapered pipe thread connector is identical to and interchangeable with the BSPT (tapered) connector. The Japanese male thread does not have a 30° Flare, and will not mate with the BSPP female swivel with conical seat.
The seal on the Japanese tapered pipe thread connector is made on the threads. Use of a thread sealant is recommended.

Thread form per JIS B 0203 (identical to BSPT)

JIS Tapered Pipe Thread

2. JIS 30° Flare (Female Internal Cone Seat)

This connection uses a 60° concave (inverted) seat and British Standard Pipe Parallel threads. They are not interchangeable with BSPP conical seat couplings, because the cone seats are opposite.

Thread form per JIS B 0202 (identical to BSPP)

JIS Tapered Pipe Thread

3. Komatsu 30° flare (Female Internal Cone Seat)

Threads commonly used on Komatsu equipment (30° cone) have metric thread form.

Komatsu 30° flare Female Internal Cone Seat

MALE THREAD OD & PITCH DASH SIZE FEMALE THREAD ID
mm mm
M14 x 1,5 -1415 12,5
M18 x 1,5 -1815 16,5
M22 x 1,5 -2215 20,5
M24 x 1,5 -2415 22,5
M30 x 1,5 -3015 28,5
M33 x 1,5 -3315 31,5
M36 x 1,5 -3615 34,5
M33 x 1,5 -3315 31,5

4. Komatsu Style Flange Fitting JIS B 8363

The Komatsu style Flange fitting is nearly identical to, and fully interchangeable with, the SAE Code 61 flange fitting*. The O Ring dimensions are different between all sizes. When replacing a Komatsu style flange with an SAE style flange, an SAE style O Ring must always be used. *5/8” is not in the SAE Standards.

BSPT & BSPP Threads Dimensions

BSPT & BSPP SIZE & PITCH DASH SIZE BSPT MALE THREAD OD BSPP MALE THREAD OD BSPT FEMALE THREAD ID BSPP FEMALE THREAD ID
inch-TPI mm inch mm inch mm inch mm inch
1/8 – 28 -02 9,5 0.37 9,6 0.38 8,4 0.33 8,6 0.34
1/4 – 19 -04 12,8 0.50 13,0 0.51 11,2 0.44 11,9 0.47
3/8 – 19 -06 16,3 0.64 16,5 0.65 14,7 0.59 15,2 0.60
1/2 – 14 -08 20,4 0.80 20,8 0.82 18,3 0.72 19,1 0.75
5/8 – 14 -10 22,5 0.89 22,8 0.90 20,6 0.81 20,8 0.82
3/4 – 14 -12 25,9 1.02 26,3 1.04 23,9 0.94 24,6 0.97
1 – 11 -16 32,6 1.28 33,1 1.30 29,7 1.17 30,7 1.21
1.1/4 – 11 -20 41,1 1.62 41,8 1.64 38,6 1.52 39,4 1.55
1.1/2 – 11 -24 47,0 1.85 47,7 1.88 44,5 1.75 45,5 1.79
2 -11 -32 58,6 2.31 59,5 2.34 56,4 2.22 57,4 2.26
2.1/2 – 11 -40 74,1 2.92 75,1 2.95 71,9 2.83 72,6 2.86
3 – 11 -48 86,6 3.41 87,9 3.46 84,6 3.33 85,4 3.36

Thread size refers to the nominal bore of the pipe.
Subtract approx.1/4″ (6 mm) from thread diameter measurement for nominal pipe size.
Pitch is Threads Per Inch (TPI). “Gas”, “R” & “G” also refer to BSP. “Male Iron (Pipe)” may be BSP or NPT.