Tapping Valve Sacrifice?

[gt5879c]

I was once told by a senior engineer that when you install a tapping sleeve and valve to hot tap a force main, you have to install another valve, like a plug valve, because you have to sacrifice the tapping valve. I can't remember why? Any ideas?

 

[bimr]

There is an isolation valve between the tapping machine and tapping fitting. After you pull the tapping machine away, you have to shut off the isolation valve. See the diagram:

http://www.koppl.com/pdfs/Hottap.pdf

 

[SteveWag]

The “tapping” valve tends to be an AWWA 100% opening gate valve. Most tapping sleeve manufacturers us the latest design, and this seems to be a resilient seat design. If the valve operator (nut) is installed vertically, the valve can be used as any other gate valve. Sometimes a tapping valve is installed with the operating nut horizontal or otherwise not suitable for above ground operation. In this case the valve is shut and opened once and abandoned in place. Your reference to force main and plug valve seems to indicate waste water service. Perhaps your co-worker preferred a plug for that service and did not (as I) feel that the gate was correct for this service.
Steve