JIC Torque Specifications
Align the tube on the flare (nose) of the fitting body and tighten the nut using one of the two methods below.
- Flats from Wrench Resistance (FFWR) or “Flats” method
- 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.
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:
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.
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. Check out this hydraulic fitting torque chart.
|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|