The Hyperion Water Reclamation Plant is the largest sewage treatment facility in the Los Angeles metropolitan area, treating 450 million gallons per day. When tide and plant hydraulic conditions allow, plant effluent flows with the help of gravity through a 120-inch diameter butterfly valve to the plant’s 5-mile outfall pipeline without the use of pumps. Failure of any of these valves could create a backflow event, which would flood the plant.
During a comprehensive inspection, Hyperion officials discovered deterioration of its primary outfall pipeline, which wasn’t unusual given that the pipeline and pump header were over 60 years old. The inspection also revealed that ten old isolation butterfly valves on the suction and discharge sides of the vertical turbine effluent pumps needed to be refurbished or replaced due to corrosion of the valve body and disc.
Moog Flo-Tork designed an actuator that required 3,200 cubic inches (13.9 gallons) of hydraulic oil per stroke with a rated working oil pressure of 3,000 psi for the Hyperion Water Reclamation Plant’s ocean outfall pipe.
To repair the pipeline, maintenance and construction crews needed to divert the treated wastewater to an emergency one-mile outfall pipeline. The city’s Environmental Engineering Division determined that Hyperion crews and suppliers would need to work around the clock for six weeks to minimize impact on plant operations and the environment.
While refurbishing valves can save money, it can often take longer than installing new products. Existing valves must be inspected to determine if refurbishment is a viable option, and given the location, these valves could not be extracted until the project had begun. This would delay the project’s timeline, as parts would need to be located and ordered when work should already be underway. The Los Angeles Department of Public Works (LADPW) had documented that the five existing 60-inch butterfly valves and the five 78-inch valves were Pratt®-brand valves installed in the early 1970s. Knowing this information meant original project files, parts and replacement valves could be on hand before starting the work.
However, there was one exception: the 120-inch gravity-fed butterfly valve critical to public safety and plant operations. If this valve were to fail in the open position at high tide, ocean water from the bay and effluent would back up the pipe and potentially flood the facility. There was no secondary valve, but rather a redundant cylinder for closing and opening the valve.
The critically important butterfly valve was custom-made with no original manufacturer marking to be found. Given the time constraints, replacing it with a new butterfly valve was the only viable option. This also meant that a new actuation system would be required.
“The available pressure from the hydraulic power units was about 1,200 psi, and we were looking for an actuator that would produce one million inch-pounds of torque,” said Sam Navid, construction manager for the City of Los Angeles’ Environmental Engineering Division.
Moog Flo-Tork designed an actuator that required 3,200 cubic inches (13.9 gallons) of hydraulic oil per stroke with a rated working oil pressure of 3,000 psi. This system would produce up to 3 million inch-pounds of torque from either one of the two rack-and-pinion actuators, which accommodated the need for redundancy. Even though the two actuators are mechanically sandwiched together, they act as independent primary and emergency backup actuation systems.
“The new actuation system worked very well in tandem with the new butterfly valve because Moog Flo-Tork and Pratt worked closely together throughout the design, fabrication, testing and installation,” said Navid. Since the installation, all 11 valves have operated flawlessly, giving plant managers and residents an upgraded level of safety and providing necessary protection of the beautiful Santa Monica Bay shoreline. WW
Mueller Water Products is one of the largest manufacturers and distributors of fire hydrants, gate valves, and other water infrastructure products in North America. For more information, visit muellerwaterproducts.com.
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