Wessex Water, Durleigh Reservoir – Pipeline Cleaning Case Study
Pipe Descaling: A Look at the Pipeline Cleaning Services by RGL
• Sector: Water – Utilities
• Task: Descaling of clean water pipeline
• Location: Wessex Water, Durleigh Reservoir, Somerset
• When: November 2013 Client: Wessex Water
• Client: Wessex Water
• Pipe Descaling sub-contractor: RGL
• RGL plant: High pressure portable diesel driven water jetting unit (20-30 litres per min. /400-600 bar) with hand held low recoil safety lance and rotary nozzle, and rotating pipe cleaning head, wheeled nozzle centraliser and remote control foot pedal
RGL’S PRESSURE CLEANING SERVICES : PIPELINE CLEANING
Wessex Water provides water and sewerage services to an area of south west England. It is responsible for providing water to Bath, Dorset, parts of Somerset and Wiltshire. As such it has multiple sites situated in the south west including 200 water sources and water treatment works, 200 pumping stations, 340 service reservoirs and more than 11,000 km of water mains.
Due to the crucial nature of the service Wessex Water provides, it is essential that maintenance work is planned in advance, and does not affect the service it offers to its customers. RGL were contacted regarding a requirement to descale a section of pipework in a clean water line. Due to a shutdown at another plant the work was required within a tight timescale. RGL was selected having previously carried out similar work for Wessex Water.
The work involved descaling sections of critical pipework. Wessex Water removed a heavily scaled mixer tube with baffles and lifted it to an adjacent lay down area ready for descaling. This gave access to the inlet pipework which was also heavily scaled up.
RGL started with descaling the inlet pipe while insitu and undertook this work using a high pressure diesel powered jetting unit and rotating pipe cleaning head. The jetting unit ran at a pressure of 600bar providing a flow of up to 30 litres of water per minute. The head was fitted with two 90 degree jets and two 45 degree rear facing jets. It was thus able to pull itself up the pipe whilst cutting the scale and flushing the removed debris simultaneously.
The operator controlled the jet via a foot pedal and eliminated the need to be positioned close to the work face. It is possible to use this method on pipes with bends ranging in diameter from 12.5mm to over 2000mm.
Once this inlet pipe had been cleaned the jetting unit was relocated to undertake the removal of the scale from the mixer tube with baffles. This work was undertaken with the jetting unit operating at 400bar and using up to 20 litres of water per minute while connected to a hand held low recoil safety lance and rotating nozzle. RGL decided to implement the use of a safety gun to remove the scale from this section due to the awkward shape of the mixer tube. This allowed the operator greater flexibility to manoeuvre the jet to ensure all areas were thoroughly cleaned, even behind baffles.
A lower pressure was selected on the mixer tube with baffles as the lining of the pipe had to be left intact. By using the safety lance the jet itself was closer to this lining than in the previous operation completed with the pipe cleaning nozzle. The descaling work was completed within 4 hours of RGL’s arrival in site, providing adequate time for the mixer baffle to be reinstalled to the clean waterline and for the plant to resume functionality before the closure of another site was implemented.
This scale is particularly difficult to remove without damaging the protective coating system. The use of two spinning high pressure water jets, proved to be an ideal solution.