Customer-friendly quick fix
Using spray-on epoxy resin linings is a proven method of renovating water mains, but long curing times can disrupt water supplies. Now, however, a fast-drying alternative is availableSpray-applied epoxy resin linings have long been accepted by water companies as a cost-effective way of maintaining water quality and flow characteristics in ageing water mains. Although less disruptive than replacement, resin re-lining typically means water supplies will be interrupted for around 36 hours to renovate lengths of main - a 16-hour resin curing time followed by CCTV inspection, chlorination and flushing.
Pressure to reduce mains renovation time is increasing as water competition forces utilities to pay greater heed to their customers, and legislation coming into force next year makes it financially desirable to minimise periods of roadworks. In conjunction with coatings manufacturer E Wood, pipeline specialist Pipeway has sought to speed the process up by developing a spray lining with a shorter curing time. Their work gave rise to Copon Hycote 169 (169), a solvent-free polyisocyanate lining based on interpenetrating polymer network (IPN) technology, which cures in 30 minutes.
The new coating meets Drinking Water Inspectorate requirements, complies with the Water Regulations Advisory Scheme (WRAS) and BS6920 and also has DETR Reg 25 (1)(a) approval for use with potable water. The product has been used by Yorkshire Water, Severn Trent, South East Water, South West Water and Essex and Suffolk Water.
The liner is centrifugally spray applied and gels within 30-40 seconds. After 10 minutes CCTV inspection is possible and after 30 minutes the main can be sterilised, flushed and returned to service following the same procedures as an epoxy lined pipe. The result is typically a 12-hour break in water supply and a lining which should last for around 50 years. According to Pipeway's commercial manager Steve Webber, water companies have noticed "a significant reduction in customer contact with call centres" during jobs which have utilised 169.
Because the disruption of supply is shortened the need for rider mains and temporary water supplies is greatly reduced, the cut in curing time makes it possible for up to three lengths of main to be lined during a 12-hour day. Pipeway believes a large market for 169 will be in the rehabilitation of large-diameter trunk mains. Sections of the main can be isolated, cleaned, lined and returned to service overnight, negating the need for rider mains. Yorkshire Water is currently undertaking trials with 1.5mm 169 coatings on 33in cast iron mains.
Although Steve Webber believes the rapid-curing lining will never totally replace traditional epoxy resin products, he feels uptake is likely to grow as utilities slowly become more convinced of the product's benefits. At £9.50 per litre 169 is more expensive than epoxy resin, but Webber believes this is offset by the increases in lining production.
Pipeway's role in 169's development was to ensure E Wood's rapid setting product was acceptable from an application point of view, and although other contractors are accredited to use the product, Pipeway is the sole supplier of the application rigs and conversions allowing conventional rigs to deliver 169. The equipment to apply 169 is similar to that currently used to deploy two-part epoxy resin products and consists of an air-driven positive displacement metering pump with monitoring equipment calibrated to give a mix ratio to ± 5%. Lining hoses, in-line static mixers and application heads are all specially designed for 169.
Whilst Pipeway takes care of the rigs and training of its own and other companies' crews to use the new lining system, a company called Pipeline Polymers promotes 169 to the water companies. Steve Webber does not bemoan the fact that his company is not the only contractor accredited to work with the new lining system because he feels water companies would not look favourably on a single company having a monopoly on 169. "Water companies always want five to six contractors to go to in order to get the best price, they want to make sure they get value for money," he said. "Pipeway," he added, "also wants to be seen as a provider of equipment and technical support."
Steve Webber believes there is a significant market for a spray-on lining which can provide structural integrity. Because 169 is rapid setting it is possible to quickly overline and build up the lining in layers, and in a bid to expand the range of applications for the product Pipeway is looking at taking advantage of its current approval agreement which allows the company to apply 169 to a thickness of up to 6mm. Meanwhile, Pipeway and E Wood are continuing in their research and development programme to produce a product that will bridge gaps and fill holes but can still be used with standard pipe couplings and fittings.