Flowserve Nordstrom Dynamic Balance Plug Valve and Double DB Plug Valve - Manual (Page 13)

Flow Control
Nordstrom Valves
FCD NVENIM2005-01 Dynamic Balance ® Plug Valve and Double DB ® Double Isolation Plug Valve 13
5.7 Video Training
It is often difficult to schedule training in one place and time suitable
for all of the people who need to attend. Flowserve Sulphur Springs
has solved this logistics problem by offering a series of training ses-
sions on video and DVD. For your Dynamic Balance Plug Valves, we
suggest the following titles:
• Operation and Maintenance of Nordstrom 400-D Handgun and
Hypregun-Plus
• Maintenance of High-Pressure Nordstrom Plug Valves
To obtain copies, contact your Flowserve Sulphur Springs sales
representative or customer service representative.
5.8 Introduction
The maintenance procedures outlined in this manual are designed to
help you re-establish quick and easy operation, drop-tight shutoff,
and a long service life for your Dynamic Balance Plug Valves.
a CAUTION: Some procedures listed in this manual can be
performed with the valve in-line and under pressure; others
require that the valve be removed from line pressure before
performing. Those procedures that require the valve to be
removed from line pressure will be so noted.
Pressure can become trapped in the valve body cavity even after line
pressure has been removed.
Before removing pressure-retaining parts, be sure to:
• Cycle the valve after line pressure has been removed.
• Stand away from the valve when removing the Gland and Cover.
A number of procedures in this manual may cause flying debris that
may cause eye injuries. Safety glasses should be worn at all times
while repairing and maintaining Dynamic Balance Plug Valves.
The procedures described in this manual are intended only for
Dynamic Balance Plug Valves. They are inappropriate for any other
brand or type of valve.
5.9 Earlier Designs
The “First Generation”
First generation Dynamic Balance Plug Valves were primarily
designed for oil field applications. They differ slightly from the valves
discussed in this manual, but function in the same way and are
serviced in the same manner.
The first generation and design Dynamic Balance Plug Valves are
identified by the 76 in the Figure Number on the Nameplate and have
a maximum temperature rating of 250ºF.
First generation valves differ from later design valves in two ways:
1. The bottom Cover Weatherseal is a stainless steel band that
protects the cover bolting from corrosive agents by enclosing
sealant in the area between the Body and Cover. The Weatherseal
is fastened in a manner similar to the metal strapping used on
shipping cartons and is difficult to replace on-site. To repack the
cover-to-body joint without replacing the band-type Weatherseal,
the bottom Cover must be removed and the area between
the Cover and Body must be filled with a good-quality silastic
compound.
2. The Stem Packing is a set of molded elastomeric seal rings.
Relief Fitting
Dynamic Balance Plug Valves manufactured through early 1988 had
a Relief Fitting. The Relief Fitting was located above the Sealant Fit-
ting (when viewed from the side of the valve). Dynamic Balance Plug
Valves that have the Relief Fitting function the same and are serviced
the same as the valves in this manual.
Figure 2 – Location of Relief Fitting
4&"-"/5'*55*/( 3&-*&''*55*/(
5.10 Basic Construction Principles
To develop a plan of proper maintenance, it is best to understand the
basic principles involved in Dynamic Balance Plug Valves.
The lubricated plug valve was invented by Sven Nordstrom in
1914, and essentially represented an application of Pascal’s Law
of Hydraulics to the dry plug cock. Mr. Nordstrom created a valve
sealant system to prevent taper lock in plug valves and to enable
the valve closure member to be operated easily. As valve services
became more severe and as technology improved, several design
improvements were made. However, the basic principle of the use of
Pascal’s Law has not changed and is used in the sealant systems of
lubricated plug valves today.
All Flowserve Nordstrom Lubricated Plug Valves use the same basic
principles of design. In the Dynamic Balance Plug Valve, these prin-