8-Steps to Safer Hydraulic Squeeze-Offs
Be sure to observe your company’s safety procedures concerning static electricity and controlled release rate for the PE Pipe being used.
Know Your Tools
Before using any manufacturer’s hydraulic squeeze tool, familiarize yourself with the Operations Manual for that tool as well as your company’s procedures for using that type of tool. Inspect the tool and the hand pump/hose assembly for leaks and/or damage. Examine the hoses for cuts, crimps and evidence of abuse. Clean both quick-disconnects, then couple them together to check for complete threaded collar make-up.
Unscrew the filler plug on the top of the pump reservoir and check the oil level. It should be within 1/4” to 1/2” from the top. If needed, add Hydraulic Medium Oil; ISO 32 of SUS 159 viscosity.
NOTE: On pumps supplied prior to 09/1988, the air vent-filler plug on the top of the pump reservoir must remain open, two or three turns, to permit breathing.
Couple the Quick-Disconnects to the Squeeze Tool
Couple the quick-disconnects to the squeeze tool, making certain the threaded sleeve on the female coupling has been completely screwed onto the male coupling, or it will result in a partially open coupler and block the flow of oil to, or from the cylinder.
Remove Lower Jaw
Remove Lower Jaw before proceeding to this next step. (Failure to do so will result in severe damage to the squeeze tool). Operate the squeeze tool through a complete compression and retract cycle. This will bleed any existing air out of the hydraulic circuit.
Know Your Pipe
Identify diameter and SDR number of the PE pipe to be squeezed so you can properly position the lower jaw of the squeeze tool to utilize the correct gap-stop need for the diameter and wall thickness of the pipe you are about to squeeze. Inspect the pipe for surface damage. Remove any dirt from around the “squeeze zone” of the pipe. If possible, inspect the inside surface of the pipe. A rough, textured interior pipe surface is much more difficult to squeeze-off than a glassy smooth interior surface.
Protect Yourself from Static Electricity
Never position any metal tool on PE pipe until the tool is properly grounded. Static electricity can exist on the outside surface of PE pipe, and separately on the inside of PE pipe. A static electric discharge from the inside surface could burn a pinhole through the pipe and/or spark a dangerous gas fire. NOTE: Mustang SEG-30 Static Electric Discharge Assembly can be adapted to any Mustang Squeeze Tool manufactured since 1972. The solid copper and brass components are designed for the high-voltages possible during the squeeze-off procedure.
Line-Up & Square the Tool
Visually center and square the squeeze tool on the pipe before you start squeezing. Insert the lower jaw, with the proper gap stop facing up, until the cross-bar contacts the frame for proper gap stop position. Pump the hand pump until you achieve a partial squeeze-off of 10-15%, then stop and visually check that the tool’s lower jaw is parallel with the upper jaw. Next, visually verify that equal space exists between the frame of the tool and both sides of the pipe. If the upper jaw is tilted to one side, the tool is not centered and you will not achieve an effective squeeze-off. Maintain a squeeze rate of between 1-2 minutes per pipe diameter-inch, depending on the pipe’s physical characteristics (i.e. 6 min. to squeeze a 6” pipe)
Pump to a Gauge Pressure of 3750 psig – then STOP
Upon reaching 3750 psig, allow 1-2 minutes per pipe diameter-inch for cold flow relaxation of the PE pipe. A pressure drop will indicate that cold flow relaxation has taken place. Re-pump to 3750psig; an effective squeeze-off should now be achieved.
Install the Saddle Clamps
Immediately upon completion of squeeze-off, evenly torque the hex nuts until a drop in hydraulic pressure of 150-200 psig is observed. Be sure to loosen or remove the saddle clamps before releasing the hydraulic pressure. Please put the following for #9: 9. Controlled Squeeze Release Rate Controlled squeeze release rate is VERY important! DO NOT rush retraction of the upper jaw. The squeeze release rate for large diameter PE pipe (6-24”) should be controlled using 1-2 minutes per diameter inch to achieve upper jaw contact release. Slow release of the saddle clamps can assist in the release rate or a flow control valve can be installed on the retract hydraulic quick disconnect block.