Steel Pipe Swivel Adapters
Conformance
- SAE J514
- 30° Chamfers. Most of Tompkins NPSM pipe swivel union fittings have 30-° chamfers on NPTF male end of fittings. This chamfer is optional per SAE J514. If chamfer is mandatory, consult with our customer service department to verify chamfer exists on item you are requesting.
Materials
- Steel - Trivalent chrome plating per ASTM B633-98 (Type II SC-2).
- Download the Trivalent MSDS:
Trivalent MSDS
- Stainless - Type 316 (When ordering stainless, include the prefix SS at the beginning of the part number).
Working Pressures
The following table lists the recommended working pressures for steel NPSM pipe swivel union hydraulic
fittings made in accordance with SAE standard J514. Many factors such as impulsing, vibration, mechanical
shock and overtightening may affect the integrity of the fitting and swivel union connection. Tompkins
and SAE recommend sufficient testing be conducted to assure that performance levels will be safe and
satisfactory, especially if installed in systems operating at elevated pressures or in severe conditions.
When using fittings with different size or thread type, use the lower pressure rating of the two threads.
CAUTION: NPSM pipe swivel unions are not designed to provide structural support for other components.
SAE J514 NPSM Pressure Ratings
| Dash Size |
Flared Thread Size(Inches) |
4 To 1 Minimum Burst PSI |
| -2 |
1/8-27 |
5000 |
| -4 |
1/4-18 |
5000 |
| -6 |
3/8-18 |
4000 |
| -8 |
1/2-14 |
3500 |
| -12 |
34-14 |
2250 |
| -16 |
1-11 1/2 |
2000 |
| -20 |
1 1/4-11 1/2 |
1625 |
| -24 |
1 1/2-11 1/2 |
1250 |
| -32 |
2-11 1/2 |
1125 |
See SAE Straight Thread O-Ring Section for assembly instructions and torque values for installation
of NPSM Swivel Unions with O-ring straight threads.
See NPTF Pipe Section for assembly instructions and proper thread engagement for NPSM Swivel Unions with pipe threads.
Torque Values The torque values provided by Tompkins Industries are to provide benchmarks that we
believe give optimum results for leak free connections. Actual torque values should be based on individual applications.
Recommended NPSM Swivel Union Assembly Instructions
- Step 1. Inspect male pipe fitting connecting to swivel and confirm that it has an internal 30-degree
chamfer. Do not install into union if chamfer is missing.
- Step 2. Lubricate the threads and the entire chamfered area of male fitting with hydraulic fluid or
other light weight lubricant.
- Step 3. Install lubricated pipe fitting into swivel nut and turn nut until finger tight.
Step 4. Place wrench on hex of male fitting to prevent male fitting from turning, and torque
swivel nut to the values in the following table.
CAUTION: When torquing swivel nut on straight swivel union fittings, it may be necessary to also place a third wrench on the fitting wrench pad to prevent the fitting from backing out of its port while torquing
the swivel nut.
| Dash Size |
Flared Thread Size(Inches) |
Torque Foot/Lbs |
| -2 |
1/8-27 |
13 |
| -4 |
1/4-18 |
20 |
| -6 |
3/8-18 |
25 |
| -8 |
1/2-14 |
47 |
| -12 |
3/4-14 |
84 |
| -16 |
1-11 1/2 |
129 |
| -20 |
1 1/4-11 1/2 |
152 |
| -24 |
1 1/2-11 1/2 |
152 |
| -32 |
2-11 1/2 |
300 |
Alternate Assembly Method
- Step 1. If torque method not possible, follow steps 1-3 above, then proceed to the steps below.
- Step 2. Place wrench on hex of male pipe fitting and consider this wrench in the 12 o’clock position.
- Step 3. Lightly wrench tighten the swivel union nut until there is firm resistance.
- Step 4. Place second wrench on swivel union nut so that the wrench is as near the 3 o’clock position
as possible.
- Step 5.. Rotate wrench in 3 o’clock position counter-clockwise to no less than the 1 o’clock position,
but no more than the 12 o’clock position.
Why Wet Torque?
Due to differences in plating types and thicknesses, materials and
thread quality of components, the coefficient of friction
can vary widely on any given assembly. Lubrication not only
produces a more consistent coefficient of friction, it increases
clamping force on sealing area with less torque on the threads.
Over-tightening causes threads to yield, deform and therefore lose the
ability to maintain an adequate load or clamping force on the
seating area. Extended operation and severe conditions cause
further yielding which promotes possibility of leaks. Improper
installation is the primary cause of leaks in hydraulic
connections.
Tompkins firmly recommends the application of the wet-torque method during installation. When you choose not to wet-torque, consistency and quality are compromised for the sake of convenience.
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