JIC Flared Fitting

Male JIC Union

 

This connection is widely used in hydraulic systems. When the straight threads are engaged, the 37° male seat seals on the 37° female flare seat.

A 37° fitting body will accept both inch and metric tube by changing the sleeve. The 37° adapter body are available in a variety of port end configurations.

 

 

Pressure Ratings      

SAE Dash Size Nominal Tube OD (inch) Thread Size 37° Flared Tube Ends (psi) 37° Female Swivels (psi) SAE BOSS Studs (psi) SAE Boss Adjustable Studs (psi)
-02 1/8 5/16 24 UNF 5,000 5,000 5,000 5,000
-03 3/16 3/8 24 UNF 5,000 5,000 5,000 5,000
-04 1/4 7/16 20 UNF 5,000 4,500 5,000 4,500
-05 5/16 1/2 20 UNF 5,000 4,000 5,000 4,000
-06 3/8 9/16 18 UNF 5,000 4,000 5,000 4,000
-08 1/2 3/4 16 UNF 4,500 4,000 4,500 4,000
-10 5/8 7/8 14 UNF 3,500 3,000 3,500 3,000
-12 3/4 1-1/16 12 UN 3,500 3,000 3,500 3,000
-14 7/8 1-3/16 12 UN 3,000 2,500 3,000 2,500
-16 1 1-5/16 12 UN 3,000 2,500 3,000 2,500
-20 1-1/4 1-5/8 12 UN 2,500 2,000 2,500 2,000
-24 1-1/2 1-7/8 12 UN 2,000 1,500 2,000 1,500
-32 2 2-1/2 12 UN 1,500 1,125 1,500 1,125

 

SAE Dash Size Nominal Pipe OD (inch) Thread Size NPTF & NPSM Fittings w/ NPTF Pipe Threads (psi) Fittings w/ NPSM Female Swivel (psi)
-02 1/8 1/8 27 5,000 5,000
-04 1/4 1/4 18 4,000 5,000
-06 3/8 3/8 18 3,000 4,000
-08 1/2 1/2 14 3,000 3,500
-12 3/4 3/4 14 2,500 2,250
-16 1 1 11-1/2 2,000 2,000
-20 1-1/4 1-1/4 11-1/2 1,150 1,625
-24 1-1/2 1-1/2 11-1/2 1,000 1,250
-32 2 2 11-1/2 1,000 1,125
NPTF – Dryseal American Standard Taper Pipe Thread
NPSM – American Standard Straight Pipe Thread for Mechanical Joints

 

JIC Fitting Tube Assembly

For leak-free performance, the JIC Fitting requires these steps:

1: Cutting, deburring, and cleaning of the tube
2: Flaring
3. Flare inspection
4: Installation

 

Flaring
Several flaring methods, ranging from simple hand flaring to hydraulic/electric power flaring, are available.  Power flaring is quicker and produces more accurate and consistent flares compared to hand flaring. Therefore, it is a preferred method of flaring.  Hand flaring should be limited to places where power flaring tools are not readily available.  Prior to flaring, determine the tube length allowance using Table 1.  This tube length allowance should be added to the cut tube length to allow for the “loss” of tube caused by flaring.

Nominal Tube
O.D.
A
Inch Metric
1/8 0.07
3/16 0.08
1/4 6 0.09
5/16 8 0.08
3/8 10 0.08
1/2 12 0.12
5/8 14, 15, 16 0.13
3/4 18, 20 0.15
7/8 22 0.15
1 25 0.15
1-1/4 30, 32 0.20
1-1/2 38 0.18
2 42 0.28
Table 1 – Tube Length Allowance
Fitting Diagram

 

Flare Inspection
Inspect flare for dimensions and surface quality. The sleeve can be used for a quick check of the flare dimensions as shown in Figure 2.

Figure 2

Figure 2 – Comparing flare O.D. with sleeve seat and O.D.

Underflaring (see Figure 3) reduces contact area causing excessive nose collapse and leakage; or, in extreme cases, tube pull out under pressure.
Overflaring (see Figure 3) causes tube nut thread interference, either preventing assembly altogether, or giving a false sense of joint tightness resulting in leakage.

Figure 3

Figure 3 – Underflaring & Overflaring

The flare must be reasonably square and concentric with the tube O.D.; and it’s surface must be smooth, free of rust, scratches, splits, draw marks, weld beads, burrs, embedded chips, or dirt. If the flare does not meet these requirements, cut it off, take corrective action, and reflare.

 

Installation
Improper flaring or installation causes over 1/2 of the leakage problems with flared fittings. Therefore, proper installation is critical for a trouble free operation.

Figure 4
Figure 4 – Improper bend and short tube

Torque Specifications

 

Align the tube on the flare (nose) of the fitting body and tighten the nut using one of the two methods below.

  1. Flats from Wrench Resistance (FFWR) or “Flats” method
  2. Torque method

Note: Do not force an improperly bent tube into alignment (Figure 4) or draw in too short a tube using the nut. It puts undesirable strain on the joint eventually leading to leakage.

 

Flats Method
Tighten the nut lightly with a wrench (approximately 30 in.lb.), clamping the tube flare between the fitting nose and the sleeve.  This is considered the Wrench Resistance (WR) position.  Starting from this position, tighten the nut further by the number of flats from the Torque Chart.  A flat is referred to as one side of the hexagonal tube nut and equates to 1/6 of a turn.  This Flats Method is more forgiving of the two.  It circumvents the effects of differences in plating, lubrication, surface finishes, etc., that greatly influence the torque required to achieve proper joint tightness or clamping load.  Therefore, it is recommended to use this method wherever possible, and especially where the plating combination of components is not known, and during maintenance and repair where components may be oily.

Condition Recommended Tightening Method
Plating of all components is the same Either method will work
Plating is mixed Use FFWR Method
Plating of nut and sleeve/hose end is unknown
Parts are oily
Stainless or brass components

It is recommended that wherever possible, the step of marking the nut position relative to the body should be done.  This step serves as a quick quality assurance check for joint tightening.  To do this, at the initial wrench resistance position, make a longitudinal mark on one of the flats of the nut and continue it on to the body hex with a permanent type ink marker as shown in Figure 5.  Then, at the properly tightened position, mark the body hex opposite the previous mark on the nut hex.

 

Figure 5 – Make a reference mark on nut and tube body These marks serve 2 important functions:

  1. The displaced marks serve as a quick quality assurance check that the joint has been tightened.
  2. The second mark on the body serves as a proper tightening position after a joint has been loosened.

 

The flats method is slower than the torque method, but it has the 2 advantages described earlier, namely, circumvention of plating differences and a quick visual check for proper joint tightening.

 

Torque Method

With proper tube flare alignment with the nose of the fitting, tighten the nut to appropriate torque value.  This method is fast & accurate when preset torque wrenches are used.  Consistent component selection is recommended so that the effects of dissimilar plating is not an adverse factor in joint integrity.  This makes it desirable for high production assembly lines.  However, a joint assembled using the torque method can only be checked for proper tightening by torquing it again.

Note: This method should not be used if the type of plating on the fitting and mating parts (sleeve & nut/hose swivel) is not known. The torque method should not be used for lubricated or oily parts as improper clamping forces may result.  Over-tightening and fitting damage may occur as a result.

Thread Size Assembly Torque (in-lb) Assembly Torque (ft-lb) Tube Connection FFWR Swivel Nut or Hose FFWR
2 35 – 45 2 – 4 N/A N/A
3 65 – 75 5 – 7 N/A N/A
4 130 – 150 11 – 13 2 2
5 165 – 195 14 – 16 2 2
6 235 – 265 20 – 22 1.5 1.25
8 525 – 575 43 – 47 1.5 1
10 650 – 750 55 – 65 1.5 1
12 950 – 1050 80 – 90 1.25 1
14 1200 – 1300 100 – 110 1 1
16 1400 – 1500 115 – 125 1 1
20 1900 – 2100 160 – 180 1 1
24 2250 – 2550 185 – 215 1 1
32 3000 – 3400 250 – 290 1 1

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