Polyethylene Pipe Squeeze-off Procedure

To prevent possible pipe damage, it is important to control the rate (speed) of squeeze off.  A rate of 1 minute per diameter inch (i.e. 2 minutes for 2-inch pipe) is conservative and easy to remember. Any squeeze-off method must be addressed with properly designed tools and operating procedures. A suggested procedure for using Mustang Double-Bar Squeeze Tools is as follows:

Before using any squeeze tool, familiarize yourself with its construction, operation and design features.

Operation instructions for mechanical and hydraulic operated tools vary. Training in the correct use of these tools is essential if safe and efficient results are to be achieved.

The PE pipe size should be identified and the proper gap stop on the jaw positioned.

Inspect the pipe for surface damage and remove any dirt from the squeeze zone. If possible, inspect the inside surface of the pipe. A smooth finish will permit better squeeze-off than a rippled or rough texture.

The squeeze tool should be grounded to prevent static electric discharge before positioning it on the pipe.

A thorough understanding of the phenomenon of external and internal static electric discharge should be included in the training session on the use of squeeze tools. Mustang Manufacturing offers a Static Electric Grounding device that adapts to all Mustang tools.

Visually center and square the squeeze tool on the pipe and then partially squeeze 10-15%.

Determine that the upper jaw is parallel, or level, with the lower jaw and that equal space exists between the tool frame and the sides of the pipe. If the upper jaw is sloped or tilted to one side, the tool is not properly centered and should be adjusted.

After the tool is properly centered, squeeze the pipe until the hand torque on mechanical tools is “tight”.

Allow one minute per diameter inch of pipe size for cold flow relaxation. Double this time for temperatures below freezing. After relaxation, re-torque the screw approximately one-quarter turn. Hydraulic tools will achieve a “tight” level at a prescribed gauge pressure. After relaxation the pressure gauge will show a drop of 150-200psi and must be re-pumped to the original pressure. Complete squeeze-off should be achieved at this point.

Hydraulic and large mechanical tools use a pair of saddle clamps as mechanical locking devices, locking the jaws in place in the event of hydraulic failure.

Saddle clamps should be installed immediately as explained in the operation instructions for each tool. Saddle clamps can be used on mechanical tools to achieve a more precise squeeze-off by asserting additional clamping force adjacent to the squeezed pipe folds.

Release the Squeeze

Just as the rate of squeeze is important, so to is the rate of release. Rapidly retracting the tool may allow the pipe to quickly spring open and cause undo stress on the outside edges of the pipe. A release rate of ½ inch per minute is recommended.

Mark the pipe with a clamp or tape to indicate the squeeze-off area.

To avoid re-squeezing the same area in the future, the squeezed area should be permanently identified by usage of a clamp or wrapping the area in identifying tape.

Helpful Hints

When using Mustang tools in a trench or bell hole, positioning the tool 45° to the pipe permits the lower jaw to be inserted or removed with minimal side excavation of the trench wall.

Re-rounding of the pipe can often be assisted by rotating the tool 90° and pushing the pipe to a near round shape. The use of a re-rounding tool or two-piece clamp will also aid in this operation.