Managing HDPE pipe stretch
Pipe Bursting machines may use 70 tons or more of pulling force to install a municipal sewer or water main. During a pipe replacement project, the polyethylene (HDPE) pipe may stretch. This stretching can be due to friction. Ground conditions may force the old pipe to put pressure onto the HDPE pipe.
Friction may also occur when replacing homeowner sewer laterals with smaller pipe bursting equipment. Pressure is applied to the pipe when navigating a number of 45 degree bends through bell and spigot connections in a line. The operator can detect pipe stretch or pipe drag by noticing a spike, increased psi, on the pressure gauge. This spike reveals increased tonnage required to insert the pipe during the project. Because of this, it may be wise to set up a temporary connection in the line after the pipe has been fully inserted.
Pipe stretch in some cases may retract up to 6 inches overnight with municipal pipe replacements. Temporary connections will prevent a re-excavation later to repair a leak or break in a permanent connection.