Accurate documentation of pipeline locations within the network is a vital prerequisite for efficient operation of a water supply network according to the state of the art. If exact plans and documentation are lacking, then pipeline location is the proper recourse. Both metallic and non-metallic pipelines can be located.
Location of metallic pipelines and cabling
Pipeline location using the transmitter/receiver system is a low-cost method and essentially the standard for pipeline location. However, it can only locate metallic pipelines.
A transmitter is connected to the pipeline at a suitable position and induces a current. A ground stake is placed at a distance away from the pipeline to be located. A magnetic field forms along the pipeline the nature of which can be measured using a receiver on the surface of the ground.
Live cabling can also be directly located this way.
The position and depth of the located pipeline run is noted for subsequent analysis.
Pig immersion method
The pig immersion method is used for locating non-metallic pipelines such as PE, PVC or AZ.
Pipelines made of such materials cannot be located using conventional electromagnetic location methods.
For pig immersion, a device called pig is introduced into the pipeline under pressure through a launching station (tapping sleeve at a flange, bleeder valve, bypass or similar).
In the water flow, the pig opens up like a parachute and tows a locating cable into the pipeline through a pressure-tight lock.
Once the desired distance is reached, a trigger mechanism is actuated to turn out the parachute.
After location, cable and parachute are then drawn back out with ease. Once the pig is back in the tapping sleeve, it can be removed from the pipeline through the lock during normal operating state under pressure.
During pig location, sediments or incrustations can be loosened, so it can be necessary to flush the pipeline according to the standard operating procedures once the locating is finished.
Advantages of the pig immersion method:
- Immersion during normal operating state
- The pipeline need not be taken out of commission
- Ranges of up to 1500 running metres achievable
- Only one access point / tap required thanks to reversal of the flow direction
- Pipeline diameters of DN80–DN400
- Exact position and depth location