Torque/Tighten recommendations for hydraulic hose, pipes and fittings

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Tapered Thread Ports (NPT (ANSI B1.20.1), NPTF (SAE J476, ANSI B1.20.3), BSPT (BS21, JIS B 0203, ISO 7) or JIS “PT”, M-Keg (DIN 158))

The sealing is carried out through the threads. They have cone shape with and angle of 1º 47'. They use to be damaged due to overtightened. So it is recommended to be torqued with TFFT (Turns From Finger Tight). See recomended values below. Also it is recommended to apply anaerobic liquid pipe sealant around the male threads leaving the 2 first threads free of it in order to prevent system contamination. If TEFLON tape (PTFE) is used apply 1-1/2 to 2 turns in clockwise direction when viewed from the pipe thread end (the table below comes from Parker catalogue
Tapered Pipe
Thread Size
BSPT
NPTF
TFFT
1/8-28
1/8-27
2-3
1/4-19
1/4-18
2-3
3/8-19
3/8-18
2-3
1/2-14
1/2-14
2-3
3/4-14
3/4-14
2-3
1-11
1-11 1/2
1.5 - 2.5
1 1/4-11
1 1/4-11 1/2
1.5 - 2.5
1 1/2-11
1 1/2-11 1/2
1.5 - 2.5
2-11
2-11 1/2
1.5 - 2.5

JIC (Joint Industry Council) 37° flare fittings

Assembling this fitting results in a metal-to-metal seal made by the cone on the female adapter or tube flare seating onto the 37° flare on a male adapter. This metal-on-metal contact can deform the fitting’s nose over time and threaten reusability. If over-tightened, the problem can be compounded. That’s why FFWR (Flats From Wrench Resistance) is recommended in this assembly according to Parker Supplier (Parker catalogue). Other suppliers as Eaton Aeroquip recommends torque as it is showed in the following table (Eaton Aeroquip)
37º
Tube O.D. (in.)
Thread Size
Tube/hose Dash Size
Tube Connection FFWR (Parker)
Swivel Nut or Hose Connection FFWR (Parker)
Jam nut or straight fitting torque Nm (Eaton Aeroequip)
1/4
7/16-20
-04
2 1/2
2
15-16
5/16
1/2-20
-05
2
2
20-22
3/8
9/16-18
-06
2
1 1/2
24-28
1/2
3/4-16
-08
2
1 1/2
52-58
5/8
7/8-14
-10
1 1/2
1 1/2
77-85
3/4
1 1/16-12
-12
1 1/2
1 1/4
108-119
7/8
1 3/16-12
-14
1 1/2
1 1/4
-
1
1 5/16-12
-16
1 1/2
1
148-154
1 1/4
1 5/8-12
-20
1
1
173-182
1 1/2
1 7/8-12
-24
1
1
216-227
2
2 1/2-12
-32
1
1
334-352

Ferulok Flareless Bite Type Fittings

When properly assembled, the wedging action of the Ferulok design will cause the end of the tube to press firmly against the seat in the body. This action will cause the tube to develop a small indentation circumferentially on the bottom of the tube. This indentation serves as a good post assembly inspection criterion. Sealing occurs between the 24° cone of the fitting body and the hose swivel as shown. FFWR (Flats From Wrench Resistance) is the recommended method for all bite-type fittings. That’s because rebuilds can become a factor if the fittings are over-torqued.
24ºFerrule
Type
Turns
Already preset ferrule
1/6 to 1/4 from wrench resistance (lubricated)
Swivel nut assembly procedure (R6BU, C6BU and S6BU)
3/4 from finger tighten
Ferrule set
1-3/4 from finger tighten

Ermeto EO Metric Bite Type Fittings

The EO progressive ring fitting is a flareless metric fitting (for metric tube)that consists of a body, a progressive ring (ferrule) and a nut. On assembly, two cutting edges of the progressive ring “bite” into the outer surface of the tube ensuring the necessary holding power and seal for high operating pressures.
24ºFerrule
Type
Turns
Already preset ferrule
1/12 turn or 1/2 flat (30°) from wrench resistance (lubricated)
Ferrule set
1½ turns if using the fitting body (1-1/2 turns if using the hardened pre-assembly tool), oiled, from finger-tight or light wrench-resistant position.

EO-2 Metric Bite Type Fittings

The common feature of all EO-2 fittings is elastomeric seals on all joints. This assures leakfree operation without retightening — even under severe working conditions. Another breakthrough in bite-type technology is the simple assembly and cost-saving handling of the unique EO-2 Functional Nut. EO-2 is a true metric design according to 24° bite-type standards such as: ISO 8434-1, DIN 2353 or DIN 3861. It covers all three series (LL, L and S) of the broad EO tube fitting program.
24ºSealing RingRetaining RingEO2 Functional Nut
Type
Turns
Already set retaining ring
1/6 to 1/4 turns (= 1 to 1-1/2 flats) from wrench-resistant position.
Set retaining ring
1 to 1-1/2 turns from wrench-resistant position (Oiled)

O-Ring Face Seal Fittings

O-ring face seal fittings can, and should, be torqued to the recommended specifications. This is because the connection seal is made by an elastomeric seal against metal. The lack of metal-on-metal contact means that only the O-ring is being deformed in assembly and reassembly. This sealing method is very forgiving and, when assembled to the recommended torque specifications, will create a leak-free seal every.For brass, aluminum (and other soft metals) decrease torque value of the table below by 35%, however F.F.W.R. is the same. time.
O-ring