Thread Identification

International Connections

 

Guide

 

Tapered verses Parallel Threads

The first step in thread identification 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.

tapered-threads-vs-parallel-threads

 

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.

BSPP-PORT-600

Metric PORT 2

 

 

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.  

flared-seat-vs-ball-seat

 

24° Metric Compression Fittings24DEG-metric-compression-fitting

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 FittingsO-Ring-Face-Seal

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 ThreadsID-metric-threads

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

 

ID-BSP-threads

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.

 

measure-threads-calipers

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)

BSPP-600

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)

BSPT-600

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

BSPP-PORT-600

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

Metric-60-600

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

Metric-PORT-600

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

Metric PORT 2

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

Metric Compression - 600

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 (mm)   Dash Size   L Series Tube OD (mm)   Dash Size   S Series Tube OD (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

JIS-600

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

FF-600

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

Komatsu-600

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

Kobelco Compression - 600

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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