A client approached Dalco, one of Resimac’s Distributors in Canada with specialist coating and lining experience, regarding a sump that had been compromised. Its caustic contents were leaking into the ground and contaminating the surrounding groundwater.
The sump was located in the ethylene production area of a petrochemical plant close to Red Deer, Alberta. The sump, used to store drain-off from a wide variety of vessels, needed some urgent attention. Local regulators required a solution to seal the sump and stop process fluid from entering the surrounding ground water. If a solution was not implemented quickly, the plant was facing some hefty fines.
The client required Dalco to provide an economical solution that would line the underground sump and would resist further corrosive and erosive attack from the hot caustic contents. The caustic operating temperatures made the repair more challenging as they ranged from 40̊C to 80̊C.
A NUMBER OF OPTIONS
The client had to consider a number of options for the repair, which had to take into account its effectiveness, its cost and the length of time it would take. One option considered by the client was adding two inches of concrete to all internal surfaces. However, they were concerned about the timeframe and that the concrete would be too porous resulting in fluid egress over time, and so it was discounted. Another option was to line with a high build polyurethane elastomer, but this was similarly discounted on the basis that it did not offer the required temperature resistance.
To add to the plant’s expense, during the period that the tank was out of commission, a rental storage tank and booster pumps were installed. This meant that the plant manager was under pressure to come up with a solution to repair and complete the sump in the shortest time possible in order to minimise the equipment shut down time.
Dalco worked with the client’s engineers and the polymeric coating manufacturer, Resimac, to design a trench liner which would prevent loss of the corrosive media from the tank. The trench liner also needed to have the necessary chemical resistance to ensure a long-term extension to the service life of the concrete sump. After the sump was power wash cleaned and dried over-night, Dalco abrasive blast cleaned the substrate with Sponge-Jet dustless blasting technology. As an added complication, it was found that the sump had trace amounts of benzene derivatives.
This caused safety concerns which necessitated a full-time rescue team of four personnel to monitor all blasting and coating activities and ensure that all work was carried out safely.
The prepared concrete was then primed with Resimac’s moisture tolerant 505 Dampseal before application of Resimac 511UCEN, a highly chemically resistant epoxy novolac, in two coats at a total thickness of between 625-750 microns. The system was then heat cured with forced hot air at 60̊C. This was an important part of the process as it reduced the repair schedule by six days, significantly reducing downtime costs, whilst also ensuring optimum chemical resistance was achieved. The final result is a completely lined sump that was installed and returned to service in a total of 10 days. The sump is still performing well, five years on and, as a result, the method of using Resimac’s highly chemically resistant product 511UCEN with forced curing has since been used to repair a further two sumps at the petrochemical plant.■