Thread Identification | Hose And Fittings Source

Thread Identification

International Connections

Guide

Tapered verses Parallel Threads

The first step using this thread identification guide is to determine whether the thread is tapered or parallel. Tapered means the thread walls, if continued lengthwise, would eventually meet. Parallel means the thread walls are straight. A seal must be used for parallel fittings in PORT applications.

PORT Seats

In both Metric and BSPP threads PORT applications require a seal of some style for all parallel thread fittings. Here are some of the different style seals for those PORT applications.

Flared Seat verses Ball Seat

The ability to properly identify seats, chamfers and their corresponding angles is a benefit to the fitting identification. Flared seats refer to the protruding “nose cone” on the male thread or the internal flare on the female thread. Ball or Cone seats refer to the “nose cone” inside the female swivel thread that seals with the chamfer on the inside of a male thread.

24° Metric Compression Fittings

Most metric and Kobelco threads are tube application capable because of a 24° tapered throat angle that exists inside the male threads. To achieve a tube connection, a tube nut is tightened over the metric threads forcing a ferrule or cutting ring to grip the tube. When the nut is securely fastened, the ferrule squeezes the tube which holds the tube in place.

O-Ring Face Seal Fittings

This is a very common fitting in North America known as O-ring Face Seal (ORFS), but is also used with British threads (HIAB) as well as Metric threads (Metric Flat-Face). Essentially, face seal fittings seal between an O-ring located in the face of the straight male thread, and the flat face seat on the female thread.

Measuring Threads

After identifying if the threads are parallel or tapered, measure the thread pitch in millimeters over the top of the thread crests.

BSP threads come in two versions: parallel (BSPP), and tapered (BSPT). The thread flank angle for both tapered and parallel British threads is 55°. It is a fairly common mistake to identify a BSPT (tapered) as an NPT. Remember that NPT threads have a 60° thread flank angle, and BSPT has a 55° angle. This can be verified with a thread gauge. Although BSP is a foreign thread, it isn’t actually metric. This is why it comes in Imperial sizes: 1/8, 1/4, 1/2, 3/4, and so on.

Use a calipers to measure the outside diameter (OD) of the threads. On parallel threads, where you measure isn’t critical. On taper threads it is important to place the calipers on the 3rd row of threads.

Metric thread call out is the OD in millimeters followed by the pitch. Example: M22 x1.5 or 22mm x 1.5.

BSP fittings can be identified by completing a few calculations to find the thread size.

1. Measure the OD of the BSP thread
2. Take the OD measurement (inches) and subtract ¼ inch

Example: The OD measures 1″. Subtracting ¼ gives the thread size of ¾, also known as -12

Once you have the thread size, it is important to verify the pitch. The easiest way is to follow the following steps.

1. Count the number of thread crest over a ¼”
2. Multiply that number by 4 to get the number of threads per inch.

Example: If you count 3.5 thread crest over a ¼” and now multiple the 3.5 by 4, your pitch is 14 threads per inch.

• British Standard Pipe Parallel (BSPP)
• British Standard Pipe Tapered (BSPT)
• BSPP PORT (ISO 1179-1 & DIN 3852, Part 2)
• Metric 60° Cone (DIN 7631)
• Metric PORT (ISO 9974-1 & DIN 3852, Part 1)
• Metric PORT (ISO 6149 & ISO 261)
• Metric Tube Compression 24° Cone (DIN 2353)
• Japanese Industrial Standard (JIS 30°)
• HIAB BSPP Flat Face O-Ring
• Komatsu® 30° Flare (JIS Metric)
• Kobelco® Compression 24° Cone

British Standard Pipe Parallel (BSPP)

Sealing – The female swivel BSPP has a tapered ball or cone, which seals on the chamfer seat of the male.

Inch Size	Dash Size	Nominal Thread	Male Thread OD (inch)	Female Thread ID (inch)
1/8	-02	G1/8×28	3/8 (0.38)	11/32 (0.35)
1/4	-04	G1/4×19	33/64 (0.52)	15/32 (0.47)
3/8	-06	G3/8×19	21/32 (0.65)	19/32 (0.60)
1/2	-08	G1/2×14	13/16 (0.82)	3/4 (0.75)
5/8	-10	G5/8×14	7/8 (0.88)	13/16 (0.80)
3/4	-12	G3/4×14	1-1/32 (1.04)	31/32 (0.97)
1	-16	G1x11	1-5/16 (1.30)	1-7/32 (1.22)
1-1/4	-20	G1-1/4×11	1-21/32 (1.65)	1-9/16 (1.56)
1-1/2	-24	G1-1/2×11	1-7/8 (1.88)	1-13/16 (1.79)
2	-32	G2x11	2-11/32 (2.35)	2-1/4 (2.26)

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British Standard Pipe Tapered (BSPT)

Sealing – Sealing is accomplished by distorting the threads. Thread sealant tape is recommended for a leak free connection. A properly chamfered BSPT male will seal with a BSPP Female Swivel.

Inch Size	Dash Size	Nominal Thread	Male Thread OD (inch)	Female Thread ID (inch)
1/8	-02	R1/8×28	3/8 (0.38)	11/32 (0.35)
1/4	-04	R1/4×19	33/64 (0.52)	15/32 (0.47)
3/8	-06	R3/8×19	21/32 (0.65)	19/32 (0.60)
1/2	-08	R1/2×14	13/16 (0.82)	3/4 (0.75)
5/8	-10	R5/8×14	7/8 (0.88)	13/16 (0.80)
3/4	-12	R3/4×14	1-1/32 (1.04)	31/32 (0.97)
1	-16	R1x11	1-5/16 (1.30)	1-7/32 (1.22)
1-1/4	-20	R1-1/4×11	1-21/32 (1.65)	1-9/16 (1.56)
1-1/2	-24	R1-1/2×11	1-7/8 (1.88)	1-25/32 (1.79)
2	-32	R2x11	2-11/32 (2.35)	2-1/4 (2.26)

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British Standard Pipe Parallel PORT (BSPP PORT)

ISO 1179-1

DIN 3852, Part 2

Sealing – The female port has a machined flat surface (Spotface) which the male seals against.

Inch Size	Dash Size	Nominal Thread	Male Thread OD (inch)	Female Thread ID (inch)
1/8	-02	G1/8×28	3/8 (0.38)	11/32 (0.35)
1/4	-04	G1/4×19	33/64 (0.52)	15/32 (0.47)
3/8	-06	G3/8×19	21/32 (0.65)	19/32 (0.60)
1/2	-08	G1/2×14	13/16 (0.82)	3/4 (0.75)
5/8	-10	G5/8×14	7/8 (0.88)	13/16 (0.80)
3/4	-12	G3/4×14	1-1/32 (1.04)	31/32 (0.97)
1	-16	G1x11	1-5/16 (1.30)	1-7/32 (1.22)
1-1/4	-20	G1-1/4×11	1-21/32 (1.65)	1-9/16 (1.56)
1-1/2	-24	G1-1/2×11	1-7/8 (1.88)	1-13/16 (1.79)
2	-32	G2x11	2-11/32 (2.35)	2-1/4 (2.26)

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Metric 60° Cone

DIN 7631

Sealing – The male connector has metric thread and a 60° (included angle) recessed chamfer. The female has a straight thread and a tapered ball or cone seal seat. The seal takes place between the chamfer of the male and ball or cone of the tapered seal flareless swivel. The threads hold the connection mechanically.

Dash Size	Metric Thread	Male Thread OD	Female Thread ID
-12	M12x1.5	12mm	10.5mm
-14	M14x1.5	14mm	12.5mm
-16	M16x1.5	16mm	14.5mm
-18	M18x1.5	18mm	16.5mm
-22	M22x1.5	22mm	20.5mm
-26	M26x1.5	26mm	24.5mm
-30	M30x1.5	30mm	28.5mm
-38	M38x1.5	38mm	36.5mm
-45	M45x2.0	45mm	43.5mm
-52	M52x1.5	52mm	50.5mm

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Metric Threads PORT

ISO 9974-1

DIN 3852, Part 1

ISO 261 “M” Metric Threads

Sealing – The fittings have parallel threads and seal using various sealing rings, washers or metal to metal seals.

Dash Size	Metric Thread	Male Thread OD	Female Thread ID
-08	M8x1.0	8mm	7mm
-10	M10x1.0	10mm	9mm
-12	M12x1.5	12mm	10.5mm
-14	M14x1.5	14mm	12.5mm
-16	M16x1.5	16mm	14.5mm
-18	M18x1.5	18mm	16.5mm
-20	M20x1.5	20mm	18.5mm
-22	M22x1.5	22mm	20.5mm
-24	M24x1.5	24mm	22.5mm
-26	M26x1.5	26mm	24.5mm
-27	M27x2.0	27mm	25mm
-33	M33x2.0	33mm	31mm
-36	M36x2.0	36mm	34mm
-42	M42x2.0	42mm	40mm
-45	M45x2.0	45mm	43mm
-48	M48x2.0	48mm	46mm

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Metric PORT and Stud Ends

ISO 6149

ISO 261 Metric Threads and O-Ring Seal

Sealing – The male connector has a straight metric thread and an O-Ring. The female port has a straight metric thread, a machined surface and a chamfer to accept the O-Ring. The seal is created by compressing the O-Ring into the chamfer. The threads hold the connection mechanically.

Dash Size	Metric Thread	Male Thread OD	Female Thread ID
-08	M8x1.0	8mm	7mm
-10	M10x1.0	10mm	9mm
-12	M12x1.5	12mm	10.5mm
-14	M14x1.5	14mm	12.5mm
-16	M16x1.5	16mm	14.5mm
-18	M18x1.5	18mm	16.5mm
-22	M22x1.5	22mm	20.5mm
-27	M27x2	27mm	25mm
-33	M33x2.0	33mm	31mm
-42	M42x2.0	42mm	40mm
-48	M48x2.0	48mm	46mm
-60	M60x2.0	60mm	58mm

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Metric Tube Compression (24° Cone)

DIN 2353

Sealing – Sealing takes place between the 24° chamfer in the male connector and the respective sealing areas on the female ball or cone.

Dash Size LL Series Tube OD X (mm)	Dash Size L Series Tube OD X (mm)	Dash Size S Series Tube OD X (mm)	Metric Thread	Male Thread OD	Female Thread ID
-04LL	M8x1.0	8mm	7mm
-06LL	M10x1.0	10mm	9mm
-08LL	M12x1.0	12mm	11mm
-10LL	M14x1.0	14mm	13mm
-12LL	M16x1.0	16mm	15mm
-06L	M12x1.5	12mm	10.5mm
-08L	-06S	M14x1.5	14mm	12.5mm
-10L	-08S	M16x1.5	16mm	14.5mm
-12L	-10S	M18x1.5	18mm	16.5mm
-12S	M20x1.5	20mm	18.5mm
-15L	-14S	M22x1.5	22mm	20.5mm
-16S	M24x1.5	24mm	22.5mm
-18L	M26x1.5	26mm	24.5mm
-22L	-20S	M30x2.0	30mm	28mm
-28L	-25S	M36x2.0	36mm	34mm
-30S	M42x2.0	42mm	40mm
-35L	M45x2.0	45mm	43mm
-42L	-38S	M52x2.0	52mm	50mm

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Japanese Industrial Standard

JIS 30° Flare

Sealing – The male has a 30° nose and a straight thread. The female half has a 30° flare and a straight thread. This connection is similar to 37° flare. Its 30° seat and BSPP thread dimensions differentiate it from the 37° flare. The seal is created by establishing a line of contact between the male nose and the female flare. The threads hold the connection mechanically.

Inch Size	Dash Size	Nominal Thread	Male Thread OD (inch)	Female Thread ID (inch)
1/8	-02	G1/8×28	3/8 (0.38)	11/32 (0.35)
1/4	-04	G1/4×19	33/64 (0.52)	15/32 (0.47)
3/8	-06	G3/8×19	21/32 (0.65)	19/32 (0.60)
1/2	-08	G1/2×14	13/16 (0.82)	3/4 (0.75)
5/8	-10	G5/8×14	7/8 (0.88)	13/16 (0.80)
3/4	-12	G3/4×14	1-1/32 (1.04)	31/32 (0.97)
1	-16	G1x11	1-5/16 (1.30)	1-7/32 (1.22)
1-1/4	-20	G1-1/4×11	1-21/32 (1.65)	1-9/16 (1.56)
1-1/2	-24	G1-1/2×11	1-7/8 (1.88)	1-13/16 (1.79)
2	-32	G2x11	2-11/32 (2.35)	2-1/4 (2.26)

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HIAB

BSPP Flat Face O-Ring

Sealing – The seal takes place by compressing the O-Ring onto the flat face of the female. The threads hold the connection mechanically.

Inch Size	Dash Size	Nominal Thread	Male Thread OD (inch)	Female Thread ID (inch)
1/8	-02	G1/8×28	3/8 (0.38)	11/32 (0.35)
1/4	-04	G1/4×19	33/64 (0.52)	15/32 (0.47)
3/8	-06	G3/8×19	21/32 (0.65)	19/32 (0.60)
1/2	-08	G1/2×14	13/16 (0.82)	3/4 (0.75)
5/8	-10	G5/8×14	7/8 (0.88)	13/16 (0.80)
3/4	-12	G3/4×14	1-1/32 (1.04)	31/32 (0.97)
1	-16	G1x11	1-5/16 (1.30)	1-7/32 (1.22)
1-1/4	-20	G1-1/4×11	1-21/32 (1.65)	1-9/16 (1.56)
1-1/2	-24	G1-1/2×11	1-7/8 (1.88)	1-13/16 (1.79)
2	-32	G2x11	2-11/32 (2.35)	2-1/4 (2.26)

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Komatsu® 30º Flare

JIS Metric

Sealing – The male has a 30° nose and a straight thread. The female half has a 30° flare and a straight thread. This connection is similar to 37° flare. Its 30° seat and Metric thread dimensions differentiate it from the 37° flare. The seal is created by establishing a line of contact between the male nose and the female flare. The threads hold the connection mechanically.

Dash Size	Nominal Thread	Male Thread OD	Female Thread ID
-14	M14x1.5	14mm	12.5mm
-16	M16x1.5	16mm	14.5mm
-18	M18x1.5	18mm	16.5mm
-22	M22x1.5	22mm	20.5mm
-24	M24x1.5	24mm	22.5mm
-30	M30x1.5	30mm	28.5mm
-33	M33x1.5	33mm	31.5mm
-36	M36x1.5	36mm	34.5mm
-42	M42x1.5	42mm	40.5mm

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Kobelco® Compression 24° Cone

Sealing – Sealing takes place between the 24° chamfer seat in the male connector and the respective sealing areas on the female ball or cone.

Dash Size	Nominal Thread	Male Thread OD	Female Thread ID
-30	M30x1.5	30mm	28.5mm
-36	M36x1.5	36mm	34.5mm
-45	M45x1.5	45mm	43.5mm

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