FLUID POWER Steel, Stainless & Malleable Fittings 3
FITTINGS — IDENTIFICATION CHART
Fitting Thread Size Comparison Chart
The male connections have (Male unified thread class 2 fit) UN-2A specification threads and the female connections have (Female unified thread class 2 fit) UN-2B specification threads. The exceptions are male and female pipe threads. Tube Fittings
There are four basic types of tube fittings: Flare, Flareless, Straight Thread O-Ring, and Flat Face O-Ring Seal (FOR-SEAL™). Tube fittings seal in two ways. Flare and Flareless fittings use metal to metal contact joints. Straight Thread O-Ring and Flat Face O-Ring fittings use a rubber o-ring. Where extreme vibration is present, use Flareless, Straight Thread or Flat FaceO-Ring Seal fittings. SIZING: For accuracy, it is recommended the male thread be measured. Measure the outside diameter. For our example use 7/16” Next measure the threads per inch – use 20. Our fitting size measures 7/16-20. Refer to the thread chart on this page for appropriate tube size and illustration. Pipe Fittings Nominal pipe sizes do not agree with either the I.D., O.D., or thread sizes. To determine pipe size (up to 1-1/4”) measure the diameter of the threads and subtract 1/4” For example, subtract 1/4” from a 1” pipe to obtain the nominal pipe size of 3/4”. Pipe sizes can also be given in ‘dash numbers.’ A dash number is always the numerator of an inch over 16th. For instance, if the pipe O.D. measures 1/2” that would be converted to 16ths (8/16), but be written as -8.
1/2”
3/8” 1/4”
OUT IN
Flat Face O-Ring
37° Flare Flare-Twin
Ermeto 7000 Series
Straight Thread Oring SEA
45° Flare
Inverted Flare
Size
Pipe
7
1/8
1/8-27
5/16-24
5/16-24
5/16-24
5/16-24
5/16-28
3/16
3/8-24
3/8-24
3/8-24
3/8-24
3/8-24
1/4
1/4-18
9/16
7/16-20
7/16-20
7/16-20
7/16-20
7/16-24
5/16
1/2-20
1/2-20
1/2-20
1/2-20
1/2-20
3/8
3/8-18
11/16-16
9/16-18
9/16-18
9/16-18
5/8-18
5/8-18
7/16
11/16-16
11/16-18
1/2
1/2-14
13/16-16
3/4-16
3/14-16
3/14-16
3/14-16
3/14-18
5/8
1-14
7/8-14
7/8-14
7/8-14
7/8-14
7/8-18
3/4
3/4-14
1-3/16-12
1-1/16-12
1-1/16-12
1-1/16-12
1-1/16-14
1-1/16-16
7/8
1-3/16-12
1-3/16-12
1-3/16-12
1-3/16-16
1
1-11-1/2
1-7/16-12
1-5/16-12
1-5/16-12
1-5/16-12
1-5/16-16
1-1/4
1-1/4-11-1/2
1-11/16-12
1-5/8-12
1-5/8-12
1-5/8-12
1-1/2
1-1/2-11-1/2
2-12
1-7/8-12
1-7/8-12
1-7/8-12
2
2-11-1/2
2-1/2-12
2-1/2-12
2-1/2-12
2-1/2
2-1/2-8
3-12
3
3-8
3-1/2-12
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7-3-1
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