August 23, 2017

Sewer coatings built to last

As Australia’s critical water infrastructure ages, water authorities are looking for ways to rehabilitate and maintain existing assets. The method of rehabilitation needs to be durable so that it does not require regular touching up to remain effective which keeps downtime and maintenance costs low. With this in mind, Hychem’s durable epoxy system TL5 is a product that is built to last for decades.

Originally developed at the request of Melbourne Water in 1995, Hychem TL5 was formulated to suit Australian conditions. It was specifically designed to meet the needs of water utilities; long-term, fast turnaround protection of water and wastewater industry assets.

More than 20 years on, TL5 has had a hugely successful track record across all of Australia with water authorities reporting little change to linings installed 15 to 20 years ago. In comparison, water authorities noted that sacrificial coatings such as Calcium Alumina Cement (CAC) were performing as expected and had lost about 15mm of coating thickness in a five year period.

A long-lasting solution

Colin Murphy, Product Manager for Hychem, said epoxy liners such as TL5 are ideal for the harsh conditions of wastewater assets because they are chemically resistant.

“Epoxy liners have excellent chemical resistance and will stay in place with minimal erosions for years or decades. In comparison, other liners such as CAC’s will erode over time with the rate of erosion dependent on the level of hydrogen sulphide it is exposed to,” Mr Murphy said.

“We have installed TL5 on numerous assets, and our clients in the water industry have been very impressed with the long-term performance of the liner in their systems.

“The product has an attractive price point, holds up well to the rigours of the harsh sewer environment, and can last the distance. We have clients who have reported minimal change to the lining, even 20 years after installation.”

TL5 also has other advantages that make it ideal for the wastewater industry.

“Being a one-coat solution, asset owners like the fact that their asset is back in service with minimal downtime.

“TL5 is typically spray applied at thicknesses from 1mm to 6mm, and the asset can be rehabilitated and back in service in as little as six hours. This reduces asset downtime, saving clients time and money.

“It also complies with industry specifications and standards.”

For assets in areas where there is a lot of movement, Hychem’s TL5 IRF provides the same level of durability, while also providing increased flexibility to prevent cracks from forming.

20 years of installations

Hychem is routinely applied to both new and damaged structures across the nation by numerous water authorities.

Hychem TL5 was used extensively for Melbourne Water in the mid 1990s, with the Sportswood North Drop Structure one of the largest rehabilitation projects at the time. The structure was coated with TL5 at 2mm in 1995.

In July 2013, 17 years later,  Melbourne Water commissioned a coating inspection report from a National Association of Corrosion Engineers (NACE) inspector of the Spotswood drop structure. The inspector found the coating had held up well in the aggressive environment, and had seen little reduction in the thickness of the coating.

The report stated that in the highly aggressive hydrogen sulphide locations on the roof and walls of the shaft the high build coating TL5 was in good condition with no visible cracking, delamination, general breakdown or deterioration.

In another project, in 1995 Hychem TL5 was used to coat a 300 square metre section of the Geelong outfall sewer for Barwon Water.

The 2.4m outfall pipe was coated in Hychem TL5, providing excellent protection in the highly aggressive environment.

It was recently inspected by a local contractor involved in the original installation who found the coating to be in the same condition as when it was installed.

Lasting the distance

“Since it was developed over 20 years ago, Hychem TL5 has been successfully installed on numerous assets, and proven itself to be durable in the harshest wastewater environments,” Mr Murphy said.

“Water authorities can be assured that when they choose TL5 to coat their asset, they are choosing a product that will last well into the future.”

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