case study:
For Hong Kong, like other densely populated areas, handling sewage is a challenge, especially with an aging infrastructure. The network involves about 900 miles (1,448 km) of pipelines going to 280 treatment facilities, processing over 700 million gallons (2.6 billion L) of sewage per day. Maintenance is critical and ongoing.
Instead of patching existing problems or completely rebuilding manholes and other parts of the system, we proposed a long-term solution using our polyurea spray coating method to stop deterioration and strengthen walls. This entailed working with a contractor who did pipeline repair in the region.
GETTING APPROVALS
To earn approval from government officials, Rob Anderson in our USA headquarters flew to Hong Kong to demonstrate the process and define results. While the contractor had air compressors and generators that were compatible with the local electrical systems, they did not have spraying units needed for this project. We retrofitted and shipped high-speed, high-pressure coating equipment and product from the U.S. facility. It required 380 volt, three-phase wiring and a transformer box. Everything was then mounted on a flatbed truck for mobility.
APPLICATION PROCESS
The two-component polyurea coating involves heating and spraying. Our high-speed, high-pressure HighLine equipment provides the control needed for successful results. The chemical reacts quickly to form a seamless protective barrier. A second coating was applied to yield an approximate total thickness of 120 mils.
HighLine polyurea outperforms other coatings because it does not crack even as the conditions cause the surface to expand and contract. It is extremely resistant to corrosive chemicals and temperature change.
During project approval, Anderson demonstrated processing chemicals and gun operation for maximum control and performance to local applicators. Then they trained by spraying felt samples to gain experience with the equipment before working on a manhole.
Actual spraying of one manhole takes about four hours. The total time for each is one to two days depending on the size and deterioration of the manhole. This allows for all of the steps involved in cleaning, drying, repairing, spraying and curing.
Moving forward, 40 manholes were scheduled for maintenance.
The applicator ended the project by conducting tests on the polyurea applied substrate. This involved affixing 20mm dollies to the surface. After allowing the glue to set for 24 hours, the dollies were then drilled using a 20mm coring hole bit.
“Because sewers are a grid of underground tunnels that carry waste throughout the city to the treatment facilities, there are always a number of challenges facing the task,” says Anderson. “And, Hong Kong was no exception.”
Case Details
Client Details
Drainage Services Department - HK
Service Provided
Stop deterioration and strengthen sewer manhole walls using polyurea.
Project Timeline
One month
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