No waste, no panic
No-dig solutions are becoming increasingly popular, but they can run into difficulty. Now, with the development of a new range of epoxy resins, operators have greater choice – and control – over the lining process.Digging up drains is an expensive and bothersome business. Streets may have to be closed while excavators break up the road, and at the end of the operation, the road has to be restored to its original condition. A company that does that needs to have not only drain specialists, but also construction teams.
So it is no surprise that no-dig solutions are catching on. Using cameras and flexible fabric lining hardened with resin, drain repairs can be carried out through a manhole. The lining is soaked in resin and fed into a drain, and the resin is then allowed to cure until a pipe-within-a-pipe is formed.
The usual resin used is polyester-based and is cured at ambient temperatures. After it has been mixed it remains workable for 20 minutes to an hour. But that can be a problem.
In Britain, the name Dyno-Rod is almost synonymous with drain clearage. Although the company has its own operators, most of the Dyno-Rod vans on Britian's streets belong to franchise holders.
Machmade, founded in 1987 by Dave Illingworth and his brother Neil, is one of these and holds the franchise for the Merseyside. Dyno-Rod has accepted the EPROPOX range of epoxy resins for use by its franchise holders, and Machmade has been one of the first to try it out.
"We're always looking for the latest innovation, but it has to be balanced with the cost, and this will save us money," Dave Illingworth says.
Alan Carolan is excavations and relining manager with Machmade, the Liverpool franchise-holder for drain company Dyno-Rod. His staff hit the limits of polyester-based resin in last year's long hot early summer.
"We had a freak period of weather here," he says, "with temperature in the high 20s Celsius. Some of the lads were using polyester, and the liner was curing too fast. They didn't have to time to fit it before it was no longer usable."
Trelleborg has developed a range of epoxy resins that won't harden as soon. Each product in the range has a different pot life, so that operators can choose the right one for the job. When the lining is in place, curing can be started using steam or hot water, making the process more controllable.
"It's a way of minimising risk," says Machmade managing director Dave Illingworth. "There's no wasted material and no panic since it gives you plenty of time to work on it."
Carolan has been using EPROPOX HC120, which remains usable for about two hours. "It takes about one and a half to two hours to cure using hot water, and that works out well," he says.
The EPROPOX range includes resins with a wide range of pot life - from 60 minutes to 44 hours at 25°c. The resins with the longer pot life are useful for large sewers, where the liner may be impregnated at the factory or depot, thus reducing disruption on site. But Machmade mainly works on smaller pipes of 10cm to 15cm in diameter.
"There's not much room for error, and we find we get a very good finish on the liner, without any creases," Carolan says.
One of the main advantages is the reliability of the new resin. "You can tell better how long a job is going to take," says Carolan. "With ambient cure you can never quite be sure."