Flowserve 50165 Nordstrom Figure - Manual (Page 23)

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Nordstrom Figure 50165 and 50169 Dynamic Balance Iron Plug Valve FCD NVENIM2006-00 – 09/05
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Sealants
Valve sealant is a viscous material that resists chemical attack and the dissolving characteristics of line
media. Sealant performs four specific functions in a lubricated plug valve.
1. Drop-tight Seal To secure an absolutely tight seal, the film of sealant works to form a seal
between the body and plug. This seal is formed by sealant transmitted in a system of grooves
around each port. With proper selection of sealant for your particular service, this tight seal can be
retained over a wide range of temperatures and pressures.
2. Lubrication A protective film of sealant prevents metal-to-metal contact of the bearing surfaces
of the valve by filming over bearing surface irregularities. The film of sealant permits the plug and
body of a plug valve to glide smoothly over each other allowing the valve to operate easily.
3. Renewable Seat Sealant is a structural part of the valve that provides a flexible and renewable
seat. There is no need to disassemble the valve or remove it from the line to repair the seats. Injec-
tion of sealant is all that is required.
4. Plug-Jacking The fundamental operating principal of the traditional plug valve design lies in the
application of Pascal’s Law. Sealant, under pressure developed by the injection of sealant, supplies
the hydraulic means for lifting the plug from its tapered seat in the valve body thus allowing the plug
to float freely in the body and allow easy operation.
A regularly scheduled sealant injection program will allow your Dynamic Balance plug valves to operate
more easily and will extend the service life of your valves. For more information on sealant injection,
refer to Installation, Operation, and General Maintenance Manual for Nordstrom and Dynamic Balance
Plug Valves.
Flowserve Nordstrom Valves supplies many different types of sealant for use in plug valves. When
selecting Sealant for your specific services, please refer to the Nordstrom Valve Sealants brochure, or
consult your Flowserve Nordstrom Customer Service Representative
VXX Valve Purge
VXX Valve Purge, a non-hazardous formulation, was developed for cleaning valves in-line, returning
them to service without disassembly, and eliminating down time. Periodic injection of sealant into a
valve flushes debris from the sealant system and allows sealant to flow more freely. See procedures in
the Troubleshooting section.