SAE BOSS Fitting

 

O-ring Ports are the preferred port connection for use in hydraulic systems on industrial equipment and commercial products.  The adjustable O-ring fittings described in this section provide a variety of options for connections between tube, hose and pipe ends.   

 

Specifications:

  • Thread conforms to ISO 263 and ANSI B1.1 Unified
  • Port conforms to ISO 11926 and SAE J1926
  • Commonly called straight thread o-ring fittings
  • Pitch and diameter are measured in inches
  • Threads are parallel and requires o-ring for pressure tight connection
  • Thread angle is 60°

 

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

 

Torque Specifications

Adjustable Straight Thread

These Fittings include Elbows or Tees, which can be oriented toward a mating member, such as tubing, before tightening.

Unlike non-adjustable O-ring Boss connectors, the adjustable O-ring Boss connector utilizes a back-up washer which forces the O-ring into the cavity as the lock nut in tightened.

Thread Size Assembly Torque
(in-lb)
Assembly Torque
(ft-lb)
2 85 – 95 7 – 8
3 160 – 180 13 – 15
4 205 – 235 17 – 19
5 245 – 275 21 – 23
6 300 – 340 25 – 29
8 545 – 595 46 – 50
10 1010 – 1100 85 – 95
12 1250 – 1350 105 – 115
14 1675 – 1825 139 – 151
16 1895 – 1945 154 – 166
20 2550 – 2850 213 – 237
24 2850 – 3150 238 – 262
32 3700 – 4100 310 – 340

 

Assembly

Assembly

For assembly purposes, there are two main categories of parallel port ends: adjustable and non-adjustable.  Adjustable port ends are commonly found on shaped fittings to allow for proper orientation of the fitting.  Besides the elastomeric seal, adjustable port ends are assembled with a locknut and a backup washer as shown in Figure 3.  Non-adjustable port ends are found on straight fittings.

The general assembly procedure for all adjustable parallel thread port ends is the same.  Likewise, the assembly procedure is the same for all non-adjustable parallel thread port ends.

 

Adjustable Port End Assembly

    1. Inspect components to ensure the male and female port threads and sealing surfaces are free of burrs, nicks, and scratches, or any foreign material.
    2. Install o-ring on port end of fittings, if it is not pre-installed, taking care not to nick the o-ring.
    3. Lubricate o-ring with light coat of system fluid or a compatible lubricant to help the o-ring slide smoothly into the port and avoid damage.
    4. Back off lock nut as far as possible.  Make sure back-up washer isn’t loose and is pushed up as far as possible.
    5. Screw fitting into port until the back-up washer or the retaining ring contacts face of the port.  Light wrenching may be necessary.
      Over tightening may damage washer.
    6. To align the tube end of the fitting to accept incoming tube or hose assembly, unscrew the fitting by the required amount, but not more than one full turn.
    7. Using two wrenches, hold fittings in desired position and tighten locknut to the proper torque value.
    8. Inspect to ensure that o-ring is not pinched and that washer is seated flat on face of port.

SAE Figure 3
Fig. 3 Adjustable Port End AssemblySAE Step 4Step 4SAE Step 5Step 5SAE Step 6Step 6SAE Step 7 & 8Step 7 & 8

 

Non-Adjustable Port End Assembly

  1. Inspect components to ensure that male and female port threads and sealing surfaces are free of burrs, nicks, and scratches, or any foreign material.
  2. If o-ring or seal is not pre-installed to fitting male port end, install proper size o-ring or seal, taking care not to damage it.
  3. Lubricate o-ring with light coating of system fluid or a compatible lubricant to help the o-ring slide past the port entrance corner and avoid damaging it.

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