Hycote is a breakthrough product in the field of pipeline rehabilitation. It has been developed as a rapid-setting high build polymeric lining system that will confer structural properties to water mains. Based on its UK track record, this spray lining system will provide water authorities with a cost-effective alternative to conventional watermain renewal in Australia.
The product is sprayed into the host pipe (nominally 3 mm thickness) by purpose-built lining rigs. Spray lining enhances the original pipe structure and is designed to maintain its continuity in the event of most pipe failure modes typically found in small diameter pipes.
One of the key advantages is that during spraying the product does not block service connections, meaning that following the application there is no need for any secondary work to re-establish the connection or reopen the ferrule with a same day return to service. In addition, no temporary supply works are required. The product has been fully tested and evaluated in the UK to establish its mechanical performance and properties.
The spray lining system can be applied to cast or ductile iron, asbestos cement and previously coated or repaired pipes. It is now recognised as a true alternative to pipeline replacement, and the same-day return to service benefit means that spray lining is now considered to be the way forward for water companies.
Rehabilitation strategies for water mains are generally based on either burst history or a condition assessment of the pipeline to be renovated. Internal and external corrosion pit depth measurements made on exhumed pipe samples, allied to a simple corrosion model, enable predictions to be made regarding the residual asset life. This fairly simplistic approach inevitably results in mains being renewed, which are essentially sound, but may be likely to sustain only local damage during their lifetime. Extensive field trials have proven that spray lining confers structural properties when used in composite with host pipes that are merely aged, have localised damage, or have burst histories, thereby offering longitudinal continuity to the pipe and resistance to future transverse pipe fracture, with full carrying capacity maintained for a minimum period of 50 years.
Since its availability in late 2004, over 180 km of semi-structural lining has been installed in the UK and is experiencing a rapid growth in market share over traditional rehabilitation techniques. Users of the spray lining process include: Yorkshire Water, South West Water, Bristol Water, Northumbrian Water, Northern Ireland Water Services and Thames Water (about to start). Yorkshire Water has been an advocate of the spray lining process using both the structural and non-structural lining system within their renewals program. When a pipe is lined with Hycote, Yorkshire Water assumes that it has the full 50-year asset life. They are now looking at rehabilitation projects from the perspective of “is it possible to spray line this pipe” to “why can’t we spray line this pipe.” In addition, through the adoption of spray lining in their renewals program, one UK Water Authority has realised a bottom line improvement in their capital expenditure of å£20million to date. Spray Lining is now becoming recognised as a true alternative to pipeline replacement; an environmentally suitable, less disruptive, lower cost method of pipeline rehabilitation to conventional replacement / PE technologies.
Summary – Product Attributes
* Certified under AS/NZS 4020
* Rapid setting polymeric lining, 1 hour cure period before commencement of return to service
* Same day return to service
* Obviates reinstatement of service connections (does not block service connections)
* Structural properties (within normal operating parameters) enhancing original pipe structure
* High build capability – linings of up to 5 mm thickness in a single application
* Restores hydraulic capacity with a minimum 50-year design life
* Corrosion void spanning capability (up to 8 mm)
* Tough, ductile material with high abrasion resistance that at 3mm lining thickness can withstand operating pressures of 100 m head
* Maintains longitudinal continuity in the event of transverse fracture
* Cost-effective environmental alternative to conventional renewal techniques
* Lined pipe can be drilled, tapped and connected to mains using standard equipment.
Sydney Water Corporation – Spray Lining Field Trial
CLM Trenchless is the first Certified Licensee for the delivery of the spray lining system in Australia. It has acquired a purpose built spray lining rig from the UK. An experienced crew has also been employed to ensure that the technology is successfully introduced into the Australian water industry. A program of field trials was begun with Sydney Water in mid October 2007. Sydney Water has been very interested and supportive of the technology given the potential community and cost benefits that can be realised. This trial (as well as others planned in South Australia for SA Water) will validate both the technical and commercial performance requirements and benefits of the spray lining technology from the perspective of both CLMT and the Water Authorities.
Project Overview
What
Rehabilitation through spray lining of more than 1,500 metres of 100mm and 250mm CICL watermains in some of the busiest locations in metropolitan Sydney. The works will be performed by CLM Trenchless as a turnkey project which includes renovating the selected watermains through spray lining, installation of new valve connections and refurbishment of hydrants. The length of the spray lining run is typically determined by the location of valves, bends and traffic hazards.
Results
Much has been learned through this first project, which is the major objective of a trial, to address the key differences between water networks in the UK and those in Australia (and specifically Sydney Water). For example, unlike the UK, most watermains in Sydney are cement lined (some in situ). For a 100 mm diameter main this means a smaller diameter (90 mm) that typically is not uniform increasing the drag resistance of the umbilical hose used in spray lining. As part of our commitment to continuous improvement we are investigating adapting the skid design to better accommodate the cement lining, differential diameters as well as poorly installed joints.
Pipe samples taken during the trial including a main tap verified the lining quality and the ability of spray lining to successfully not block service connections. Ultimately, the key objective is to ensure that spray lining is considered an integral part of any ongoing watermain renewal strategy and program in Australia as it has successfully done in the UK.