High Pressure Water Jetting
This is a commonly used technique that employs high-pressure water jets from a specially designed pressure head that is fed from a surface located pumping unit.
The jetter head is passed through a pipe line at any desired speed and the water jets from the head are designed to hit the inner pipe wall so dislodging any debris attached to it.
The jets also pick up and remove any sediment in the pipe invert combining them into the outflow of water from the pipe. The pressure of the water ensures that all debris and silt are removed from the pipe in the direction of travel of the jetting head. Some water jets are also designed to be powerful enough to cut through root intrusions. Where water jets are insufficient to achieve root removal specially designed robots are available with low volume, very high pressure jets or rotating blades that will make removal possible. Further pressure jetting is then used to remove the debris created.
Recent developments have made these systems much more environmentally friendly with the introduction of Recycling jetters. These units not only operate with the jetter hoses to clean the pipes but also vacuum/suction equipment to recover the waste produced in the cleaning process. This recovered water is then filtered with the detritus being placed in a waste tank on board the jetter rig with the filtered water being returned to the jetter pump for reuse. Ultimately this has two advantages: first there is a much reduced need for a supply of clean water for the operation to successfully complete and second, the potential for waste spillage into the environment downstream of the work site is minimised.
An important aspect of the use of high pressure water jetting as a cleaning technique is that the correct jet nozzle should be utilised for the particular job in hand. Depending on the nature of the cleaning required nozzles are available for simple sediment removal through to hard encrustations and root cutting (as mentioned previously).
It is vital that for most pipes a thorough inspection is undertaken to establish the type of cleaning required before selecting type of cleaning nozzle or even range of nozzles that needs to be used. Consultation with experience contractors and equipment manufacturers will also aid in this selection process.
A wide range of jetter units is available from a number of manufacturers in a range of sizes and capacities to suit most pipe cleaning applications.
It should be noted that high pressure water jetting can be utilised in both pressure and gravity networks. The correct equipment and nozzle selection will depend on the type of network being cleaned as the deposits being encountered will be different for the type of pipe involved. This may also affect the form of disposal that will be required by the regulations depending on the type of waste created by the cleaning processes used.
There is a high pressure water jetting option that places the high pressure jets right against the pipe inner wall where water pipes and other pressure mains require cleaning. This ensures the highest pressure at the point of cleaning instead of a reduced pressure that might occur with a nozzle located in the centre of the pipe diameter.
Pipeline flushing is achieved in one of two ways. The first is the use of high volume/low pressure water where a volume of water is pumped into a pipeline to pick up loose sediments and scale which is passed downstream to a collection point for disposal.