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Encapsulation Method Keeps Valve Functioning, Seals Leaks
Trouble in underground infrastructure often occurs in difficult-to-access areas where making necessary repairs has the potential for disrupting normal activities.
That certainly was the case when the Public Service Electric and Gas Co. (PSE&G) discovered a leak in a 36 inch flange valve in its gas distribution system in Kearny, NJ. The valve was buried under about four feet of cover beneath a residential street.
PSE&G initiated a proactive approach to permanently fix the problem, said Vincent Guariglia, supervising engineer for the company's Harrison Gas District.
Evaluation of the problem revealed three options, said Guariglia.
"We could have replaced the valve which would have required road closures for an extensive excavation and could have caused various municipal problems," he said. "This solution also would have been very costly.
“The second option would be to cut the valve completely. However, this would have removed a critical point of control from the system, resulting in reduced system reliability in a critical situation."
Course of action
The third option – and the one PSE&G decided to take – was to encapsulate the valve while maintaining system control and valve functionality. With this process, a two part polyurethane mixture surrounds and permanently seals leaking joints, compression couplings and distribution fittings.
"There were many benefits to this approach for this situation," said Guariglia. "Sizes of excavations were minimized which reduced the expense of the project. It also left the
town content because it minimized road repairs and reduced the number of complaints from the public. However, in order to use the encapsulation method, valve functionality had to be maintained during construction."
Guariglia explained that PSE&G has successfully used the encapsulation technique in the past, but the 36-inch valve is the largest ever done.
The project contractor the project was Miller Pipeline Corp. which used its Encapseal Safe-T-Seal system on the project. Guariglia said Miller Pipeline previously completed several encapsulation projects for PSE&G.
In order to encapsulate the valve, a mold had to be designed and fabricated. The first step in that process was to uncover the leaking valve. Steve Kasmin, Miller district manager, went on site, pinpointed the location of leaks, and obtained fitting measurements and other information to design the mold which would contain the flange valve but also one innertite joint.
After measurements were completed, the excavation was covered with plates.