DIN EN 13566 / ATV-DVWK-M 143-11
Lining with close-fit pipes

Lining with close-fit pipes:
Lining with a continuous pipe for which the cross-section is reduced to facilitate installation and reverted after installation to provide a close fit to the existing pipe [DINEN13566-1:2003].

Deformation process

Reduction process

Lining with close-fit pipes

• PE- or PVC-lining pipes are used in particular.
• Pulling-in a plastic continuous pipe (lining pipe), whose cross-sectional dimensions have been reduced by predeformations, into the section to be rehabilitated.
• Subsequent expansion until it clings to the interior wall of the sewer.
• Minimising the cross section reduction of the section that has to be rehabilitated compared to the lining with continuous pipes with annular …

The preparatory works of lining with continuous pipes without annular space contain:

• Taking out of operation of the old sewer (securing the drainage capability)
• Cleaning of the old sewer
• Optical inspection of the old sewer
• Removal of roots, deposits and other drainage obstacles
• Probable sealing of groundwater infiltrations
• Measurement and calibration of the section that is to be rehabilitated

To secure the drainage capability within the scope of the employment of cured-in-place lining processes, the following possibilities are at hand:

• Interruption of the drainage capability by limiting backwater in the sewer above the section that is to be rehabilitated
• Maintaining the drainage capability by measures external of the sewer that is to rehabilitated

The following aspects are to be considered during inspection:

• Deviations in the inner diameter
• Direction changes
• Displaced joint
• Laterals
• Ground water infiltrations
• Flow obstacles
• Deformations
• Cracks, fragments, break

Removal of obstacles

Obstacles which may lead to damages when the lining pipes are pulled in or especially when they are redeformed or which may put the operating safety at risk have to be removed.

Calibration

For the correct use of lining processes, it is necessary to obtain information on the minimum inner diameter of the damaged sewer (e.g. by means of calibration measuring tools etc.) [RSV2] [RSV3].

In this group of processes, the respective plastic continuous pipes of PE or PVC specially modified for this process are predeformed into a U- or C-shape by supplying heat at the site or immediately before being pulled in so that, depending on the string diameter compared to the original cross section, a cross-sectional reduction of up to 40% [FI-Rehau] is achieved.

HD-PE-pipes have a specific internal structure due to their chemical and physical composition.

Stresses are deliberately integrated into the pipe by predeforming it, and thus a new structure is created.

The quick cooling of the deformed pipe serves to freeze this new structure.

By re-heating the predeformed pipe, it changes back to a preferably stress-free state, namely the round shape before the folding …

Factory-predeformed lining pipes are delivered to the construction site on pipe drums.

The continuous pipe is directly pulled in by the drum or by the coiled bundle (only with shorter rehabilitation sections).

Should a pulling-in excavation be necessary during the deformation process, the dimensions depend on the minimum bending radii of the predeformed pipes.

In the Subline process developed in Great Britain, the deformation of the continuous pipe is integrated into the insertion process, i.e. it is carried out in-situ with the aid of a hydraulically acting deforming and insertion device. When leaving the device, the temporary C-form of the PE continuous pipe is held by manually applied, thin, PP straps so that a cross sectional reduction …

After the pulling-in of the predeformed lining pipes, the pipe ends are sealed and the pipes are set up

• by superheated steam and/or
• internal pressure
• by using a calibre tool, if necessary.

Working steps for redeformation by means of superheated steam under internal pressure:

• Heating of the predeformed lining pipe up to the temperature that is required for the material while the internal pressure is slightly increased.
• Increase of the internal pressure while the temperature is slowly reduced.
• Maintenance of the maximum internal pressure until the lining pipe is sufficiently recooled.

Swage-Lining
Thermo-mechanical deformation of continuous pipe

In order to guarantee a smooth and continuous reduction, the external welding beads must be removed within the range of the welded joints.

In the reduction process, the length of the excavation depends on the bending radii of PE-pipes recommended by the pipe manufacturers.

In this connection, the temperature-dependent change of the permissible bending radii must be considered (cp. lining with continuous pipes with annular space).