System Experience & Training # 1998 Gothenburg
In the UK, jetting of drains and sewers is undertaken mainly for emergency clearance of blockages, rather than planned cleaning as in some other countries. Jetting equipment has been constantly upgraded to produce higher pressures in order to provide a quicker service to customers and better return on investment. Plastics pipes currently constitute a significant percentage of sewers and drains adopted for ongoing maintenance by the UK Utilities, from contractors and housing developers. Over the last three years. press articles have emerged suggesting that plastics pipes were particularly prone to damage by jetting. As a result. a number of UK Water Utilities ceased installing these products. posing a significant threat to this market. But it wasn't just plastics pipes at risk, and WRc initiated a programme to develop an independent Code of Practice to minimise the risk of damage to any sewer or drainage system. The programme was supported by manufacturers of clay. concrete and plastics pipes, together with technical support from jetting contractors and the UK Water Industry. The key purpose was to evaluate all materials on level terms and base the Code of Practice on objective criteria. The Code of Practice focuses on the condition of the pipe and on the material, and is applicable to both new and existing pipelines. Brick, masonry and pitch fibre sewers need to be jetted with care as do sewers and drains in a partially deteriorated condition. For these a maximum jetting pressure of 130 bar (1900 psi) is recommended to reduce the possibility of damase. The maximum jetting pressure is reduced to 80 bar (1 200 psi) for badly deteriorated systems. The Code of Practice thus helps protect all sewer systems from unnecessary damage. Rather than creating 3 problem for water companies and pipeline operators, the plastics pipes industry has highlighted through WRc's work the need for care when jetting all pipelines and has contributed to preparing a robust and practical Code of Practice that reduces the risk of causing damage during pressure jetting operations.