Rolldown - Tight-Fit Polyethylene Lining
PIM Corporation's Rolldown system uses standard polyethylene (PE) pipe to create a close-fitting liner within an existing pipeline. Rollers reduce the diameter of the PE pipe and allow it to be pulled through the host pipe. The liner is then pressurized to revert it to its original size. Rolldown can be designed as a stand-alone, fully rated pressure pipe, or as a thin-wall liner used to eliminate leaks in an otherwise sound pipeline.
Cold Process: No heating equipment required. The entire process is carried out at ambient temperatures.
Minimal Elongation: Low winching forces minimize residual stresses after installation.
Start-Stop Capability: The process may be stopped at any point in the installation process and then safely started again.
- Available for 4' through 20' pipe
- Wall thicknesses from 1/4' to 1 1/8' (SDR > 11)
- Installation lengths up to 3,000' in single pulls are possible
- Can negotiate bends up to 11.25° Stops leaks and internal corrosion
- Tight fit and smooth bore maximizes flow capacity
- Uses standard PE pipe with known physical properties and design life
- Holds reduced diameter indefinitely prior to reversion, allowing flexibility of installation
- Installation does not harm adjacent utilities
The patented Rolldown process can reduce the outside diameter of polyethylene pipe significantly without affecting the long-term characteristics of the pipe in any way. Unlike other diameter-reducing processes, Rolldown does not stretch the polyethylene nor weaken the pipeline material.
A polyethylene pipe which has been reduced by the Rolldown process will hold its new diameter for several days unless deliberate steps are taken to revert it to its original size.This allows much more control over the installation schedule than is possible with other processes.
As a result of the reduced diameter of the new pipe, conventional sliplining techniques are used to insert it into the original pipeline. Since winching loads are very low, neither pipe is subjected to harmful stress, even when large diameters or long lengths are installed.
After insertion into the old pipe, hydrostatic pressure is used to trigger the molecular memory of the polyethylene. This causes the new pipe to attempt to return to its original diameter. As a result, it presses tightly against the inside of the old pipe, virtually eliminating all annular space.
- Rehabilitate 4-inch through 20-inch diameter pipe
- SDR 42 through SDR 11 thin- or thick-wall, MDPE or HDPE pipe may be used
- Single installations greater than 3,000 feet have been achieved
- Normal Rolldown rate is 6 to 8 feet per minute
- Installation speed of 18 to 20 feet per minute is common
- Pipe may be butt-fused before or after rolldown
- Tests prove rolldown has no negative effect on polyethylene
- Rolldown reduces diameter without elongating pipe
- Pipe is reverted with pressurized water at ambient temperatures
- Over 300 miles of pipeline have been rehabilitated with the Rolldown process