Flowserve 50165 Nordstrom Figure - Manual (Page 21)

21
Nordstrom Figure 50165 and 50169 Dynamic Balance Iron Plug Valve FCD NVENIM2006-00 – 09/05
flowserve.com
improvements were made. However, the basic principle of the use of Pascal’s Law has not changed and
continues to be used in the sealant systems of lubricated plug valves today.
All Nordstrom Lubricated Plug Valves use the same basic principles of design. In the Dynamic Balance
Plug Valve, these principles consist of a body, plug and stem, cover, adjustment member, and sealant.
The function of each of these items is as follows:
1. The Body connects the valve to the pipeline. The body also mates with the Plug to form a pressure
vessel, capable of operation under various pressures and temperatures.
2. The Plug, rotated by operation of the Stem, has a tapered surface designed to mate with the body
taper bore to provide tight shutoff.
3. The Cover prevents external leakage and is designed to allow a finite floating of the plug.
4. The adjustment Member is provided so the position of the Plug can be set in the proper relation to
the Body.
5. Sealant is an integral part of all lubricated plug valves and has three functions:
• To ensure bubble-tight shutoff on hard-to-hold line media by acting as a secondary seal against
seat leakage.
• Provides a flexible and renewable seat, eliminating the need to force fit or replace sealing parts to
obtain a seal.
• Applies Pascal’s Law by providing the hydraulic means necessary to push the plug from its
tapered seat in the body.
Sealant System
Flowserve Nordstrom Valve Sealant functions as an integral part of the lubricated plug valve. Sealant is
the basic improvement over the dry plug cock. In order for sealant to be effective, the valve requires a
system of internal channels - the Nordstrom Sealdport Grooving System.
The Nordstrom Sealdport Grooving System provides complete shutoff of line media regardless of the
flow direction of material through the valve. Nordstrom valves can be lubricated with the plug in any
position while the valve is subjected to line pressure. With the plug in the closed position, the down-
stream port is completely surrounded by a film of Sealant between the body and plug seating surfaces.
When rotating the plug between the open and closed positions, the grooves exposed to the valve flow
passages are disconnected from the sealant system.
By maintaining a periodic sealant injection schedule, the Sealdport grooving system will sustain a pres-
surized sealant system regardless of whether the valve is in the open, closed or throttled position.