comprex® - The mechanical cleaning with air and water

Discharge of coarse particles from pipes

The comprex® cleaning process is divided into two phases:

  1. Removal and mobilization of deposits
  2. Complete discharge of the mobilized particles


When cleaning, the main focus is on removing and mobilizing deposits. However, there are also cases in which the focus is on the delivery. Debris can cause damage, especially at low points in pipelines. Abrasion leads to breakthroughs in the sole area. Chips and similar coarse particles can cause blockages if they are not removed in good time.

The patented comprex® cleaning system

Coarse particles in pipes

Debris can accumulate in low-lying areas of wastewater pressure pipes, for example in culverts, if the flow velocity is insufficient. Worksheet DWA-A 113 provides information on the minimum flow velocity required for vertical and horizontal pipes depending on the pipe diameter. If debris remains in low-lying pipe sections, the movement of the particles when the pumps are switched on and off leads to abrasion and ultimately to damage in the invert area. Wastewater enters the soil.

A large, elevated metal pipe is shown leaking water in multiple places into the dirt and rocky ground below, as if neglected after a pig cleaning operation.
Close-up of a damaged pipe with a rusted hole, positioned under a metal ruler showing a measurement scale from 2 to 8 centimeters, highlighting the need for pig cleaning to maintain pipeline integrity.
A close-up view of a corroded and partially buried metal pipe, showing signs of rust and deterioration, indicative of the need for pig cleaning to maintain functionality.

Damage caused by abrasion in the invert area of a wastewater pressure pipe*

Damage caused by abrasion in the invert area of a wastewater pressure pipe*

Wet wipes partially block the openings*

*Prosser, M. (2016): Damage to a wastewater pressure pipe; KA Betriebs-Info (46) October 2016; pp. 2540-2541

Discharge of coarse particles using Comprex® technology

There are also low-lying areas in raw and drinking water pipes. Coarse particles can cause hygiene problems here. Typical coarse particles in drinking water pipes are calottes from house connections that could not be removed with the water flush. However, lime scale can also occur in PE pipes and affect the hydraulics.

Many years of experience have shown that Comprex cleaning not only reliably removes detached deposits, but also reliably removes coarse particles.

Example wastewater pressure pipe

Coarse particles from wastewater pressure pipe after comprex® cleaning:

A close-up of a mesh basket filled with dark debris and a tar-like substance, placed next to a yellow can on the ground, likely remnants from pig cleaning.
A close-up of a black, tar-like substance spread across a textured surface with a red border on one side, resembling the remnants of a thorough pig cleaning session.
A blue-gloved hand holding pieces of dark, tar-like substance is seen, possibly from a pig cleaning task. The background is blurred with greenery.
Close-up of a gloved hand holding several pieces of shiny black material, likely tar or asphalt, reminiscent of the slick surfaces encountered during pig cleaning.

Example raw water pipe

Coarse particles in the bottom area of raw water pipes and discharge in the waterworks:

A sewer pipe interior with text overlay in German stating: "Die Rohrwandungen sind absolut sauber, keine festen Ablagerungen mehr zu erkennen. Die Pig Cleaning Methode hat super funktioniert. Auf der Sohle scheinen nur lockere Einzelteile aufgehäuft zu liegen.
A view inside a pipe shows a clear interior with some loose debris on the bottom, indicating pig cleaning might be due. The image features labeling with technical details and a date (22-03-11) in the upper right corner, along with German text.
Metallic structure in a rectangular water tank with a central circular disc; text in German at the bottom describes the water system and visible components, including references to pig cleaning processes.
A stationary mechanical component shown amidst what appears to be a wastewater treatment process, with a mixture of water and sediments visible, is often essential for pig cleaning operations.

Coarse particles from a culvert in a DN 1000 raw water pipe with a discharge point in the waterworks some 18 m higher up:

Play Video about Austrag nach comprex® Reinigung

Example drinking water pipe

Coarse particles from drinking water pipes: Spherical caps from tapping holes for house connections and limescale shells from PE pipes caused by limescale-removing water, cell phone for size comparison:

A dirty water pump and hose system next to a grime-covered area, used for pig cleaning, with the pump connected to a pipe. Several clumps of mud or dirt are scattered on a nearby concrete surface.
A T-Mobile Nokia phone placed on a concrete surface next to a large, round piece of brown material resembles the aftermath of a pig cleaning session.
A close-up image of a rusted pipe section with a buildup of fibrous material blocking the interior, indicative of the need for pig cleaning, lying on a grassy surface.
A large beige mineral specimen with small crystal formations is placed next to a smaller rock and a mobile phone for scale, reminiscent of the meticulous care seen in pig cleaning.


Comprex cleaning is always advantageous when other methods are not possible. Comprex technology allows pipe sections of several hundred meters in length as well as long culvert pipes to be cleaned. Even culverts in gravity pipes can be cleaned with the help of flow-through pipe sealing bags.

Culvert in wastewater pressure pipes and in gravity pipes:

Diagram depicting a wastewater pressure pipe system with an inverted siphon (Düker). It shows an inflow (Zulauf) from BEV 1, wastewater passing through the siphon, and outflow (Auslauf) to BEV 2, incorporating pig cleaning for maintenance.
Diagram depicting an inverted siphon system, illustrating the flow of water through a depression with inlet (Zulauf) on the left and outlet (Auslauf) on the right. The labeled sections include Dükeroberhaupt and Dükerunterhaupt, designed for efficient pig cleaning maintenance.

While connections for air release valves (BEV) serve as feed points for the Comprex pulses in wastewater pressure pipes, culverts in gravity pipes can be prepared for Comprex technology by installing the flow pipe sealing cushions.

Feeding the comprex® pressure release pulses into the wastewater pressure line:

A view inside a cylindrical manhole reveals two blue valve handles and a connected pipe, ready for pig cleaning. The ground surrounding the manhole is covered with leaves.
A white van and trailer labeled "COMPREX HAPPMANN" are parked by the roadside, engaged in pig cleaning operations at a nearby utility site via blue hoses. Traffic cones are strategically placed around the area.

Installation of flow pipe sealing cushions in gravity pipes:

A schematic diagram showing a cross-section of a tunnel with a railway track and a train entering from the left. The tunnel, possibly designed for pig cleaning processes, is surrounded by a circular area filled with gravel.
Diagram depicting a top-down view of a road cross-section with a vehicle crossing a bridge. The bridge is shown with structural elements extending into the ground below, as if prepared for a meticulous pig cleaning overhaul.

Flow pipe sealing cushion installed in manhole for cleaning a long, low-lying sewer

Flow pipe sealing cushion installed in manholes for cleaning a culvert in a gravity pipeline

Sewers and gravity pipes are often only designed for low pressure levels. Long pipe sections of several hundred meters in length cannot be cleaned with flushing vehicles, or only insufficiently. Video footage from an IKT research project in 2006 shows how even low compressed air pulses of around 1 bar can discharge gravel from transparent plastic pipes.

*Source: IKT (2006): Wastewater pressure pipes – possibilities and methods for cleaning. Institute for Underground Infrastructure (IKT), Gelsenkirchen.


In the metalworking industry, pipelines also transport chips from the processing machines to the processing system together with the cooling lubricant emulsion. It is important that the pipe cross-section and thus the flow and pressure are maintained during operation. Residual chips can impair the hydraulics and even lead to blockages. Extensive studies at Hammann and in metalworking companies have shown that regular prophylactic Comprex cleaning can make a significant contribution to quality assurance. Even if the pipelines are only designed for low pressure levels, Comprex pulses can maintain the systems. Not only mobilized biofilms, but also chips and other coarse particles are reliably transported to the preparation for the cooling lubricant emulsion.

With our comprex® process, we offer an effective, sustainable and resource-saving cleaning alternative.

Let us advise you and we will be happy to convince you with a test cleaning at your site.

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