How to Use a Swagelok Multihead Hydraulic Swaging Unit to Preswage Your Tube Fittings

The Multi-Head Hydraulic Swaging Unit comes in a kit that includes multiple dye heads, chamfer blocks, and gap gauges, as seen in the instruction manual.

Remember not to tamper with or alter the MHSU while it is in your possession. If there is visible fluid leakage from the MHSU, please contact your local Swagelok Sales and Service center before proceeding.

Before we get started, remember to put on your safety glasses. Ensure that your tube has been cut squarely and thoroughly, and verify that both the inside and outside of the tube have been deburred. Also, verify that your tubing meets minimum wall thickness recommendations.

For sizes 1 in. and smaller, we recommend that you take the correct sized chamfer block and slip it over the edge of the tube. Strike the chamfer block firmly one time with a hammer. This helps ensure that the tube fully bottoms in the preswaging tool.

Before beginning, confirm that you are using the correct MHSU tool size for the tubing that is to be preswaged. Insert the retaining ring pliers into the retaining ring holes and squeeze to remove the retaining ring. After removing the retaining ring, the current dye head should pull straight out of the MHSU head.

Choose the correct dye head based on your tubing size. There are markings on the back of each dye head illustrating the sizes. Before installation, inspect the dye head to ensure it is in good condition and free of gouges and dents, which could lead to ineffective preswaging.

The inner portion of the dye should move freely within the outer portion. Locate the groove on the outside of the selected dye head and align it with the pin inside of the MHSU head. Insert the dye head and rotate it until it drops in and sits fully as shown.

At this point, reinsert the retaining ring using the pliers from earlier. Make sure the retaining ring seats fully in the groove before releasing.

Refocus your attention to the prepared tube and corresponding fitting. Insert the tube into the fitting. Back the nut off of the fitting body and place the fitting body to the side. Inspect to ensure that you have both the front and back ferrule and make sure both ferrules are correctly positioned, pointing them towards the end of the tube.

At this point, you can insert your tubing with the nut and ferrule assembly into the MHSU head. Close the nut onto the MHSU head until it is finger tight. Once the nut is finger tight, press the indicator knob completely until the green band is hidden to confirm the indicator knob is fully compressed. Check to make sure the back of the indicator knob is flush with the back of the MHSU head.

Tighten the pump bypass valve until it is finger tight, and begin pumping the unit until the indicator knob is released. Do not use the hand pump after the indicator knob has been released. You do not need to finish the stroke. Further pumping could impact fitting performance and damage the preswaging die.

Before continuing, mark the tubing at the back end of the nut. This mark will be used later to ensure the nut has been sufficiently hand tightened when assembled to the fitting body. You can now open the pump bypass valve by turning the handle 1/2 to 1 turn counterclockwise. This will return the hand pump back to the original position.

Unthread the Swagelok nut and remove the preswaged assembly from the housing. If the tubing does not come out, make sure not to twist the tube, but rather gently rock it back and forth.

Now that the preswaging is complete, you should notice that the ferrules are captive. The ferrules may be able to move slightly, but they will not be able to be removed. Inspect the tube end for a radial indentation bottoming mark. This indentation indicates the tubing was properly bottomed in the MHSU.

If there is not a visible indentation, the preswaged assembly should not be used. This is critical to ensure fitting performance success. The MHSU should only be used to preswage a set of ferrules one time. If the ferrules were insufficiently preswaged, they should be discarded and the process started again with a new set of ferrules.

For fittings over 1 in. or 25 mm, lubricant must be applied when installing the Swagelok tube fittings. A packet of lubricant is provided with the fitting. You apply the lubricant sparingly to the Swagelok tube fitting body threads, and you also apply a similar amount of lubricant to the rear surface of the back ferrule.

You are now ready to install the preswaged assembly into the fitting body. Turn the nut onto the fitting body until it is finger tight. The line marked on the tubing earlier in the process should now be visible. If it is not, tighten the nut with the wrench until the line is visible.

Mark the nut at the 6 o’clock position. Hold the fitting body stable and tighten the nut 1/2 turn until the mark on the nut reaches the 12 o’clock position. Keep in mind that for 3/4-in. medium-pressure tube fittings, the nut needs to be tightened 1/3 turn until the mark reaches the 10 o’clock position.

Select the appropriate gap gauge included in the MHSU kit based on tubing size and position it adjacent to the gap between the nut and body hex as shown. If the gauge will enter the gap, additional tightening is required. If the gauge will not enter the gap, the fitting is sufficiently tightened.

For troubleshooting techniques, please reference the manual included in the MHSU kit or contact your local Swagelok sales and service center.