NIBCO Bronze, Globe and Angle Valves 1/ to Class 175 WWP - Manual (Page 4)

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1.3 DETAILED DESCRIPTION
The globe and angle valves listed above and covered in these instructions are bronze
valves made of ASTM B62 material for Class 125, 150, and 175 WWP valves and from
ASTM B61 material for Class 200 and 300 valves.
The valves are operated with the handwheel and are used to start, stop or throttle the
flow of fluids in piping systems. Globe and angle valves are rising stem type only. Non-
rising stem globe valves are not available. The disc is closed through a clockwise turning
direction of the handwheel.
The screwed bonnet type body and bonnet are held together by threads of the male and
female type; male threads being on the bonnet section and female threads being within
the body. There are no gaskets between the body and bonnet to affect seals. This is
strictly a metal-to-metal seal as required by standards. This general arrangement is used
on the Class 125 globe and angle valves only.
The union bonnet arrangement on 150 and 300 class has male threads on the body. The
bonnet has no threads at all; however, a union nut is placed over the bonnet to fasten it
to the body. Here the seal between the body and bonnet is also metal-to-metal without a
gasket.
Flow through globe or angle valves is stopped by forcing the disc down onto the valve
body seat. Throttling is accomplished by carefully turning the handwheel to some
position between full open and full closed. The disc is either of bronze construction
directly connected to the stem or in some cases where a soft seat is desired, the disc is
made out of PTFE or Buna-N. On bronze globe valves the disc is held in place on the.
stem by retainer bushings or in the special non-return models (N.R.) the disc is so
arranged that it travels up and down within the valve body through the use of guides on
the disc itself and it is not attached to the stem. This valve is a directional valve operated
by gravity to prevent backflow. It may also be used as a globe or angle valve; however,
the non-return feature will only operate in the direction of the flow arrow on the side of
the valve.
All valves have back seats between the shoulder of the stem and the valve body. This
was a requirement of standards so that the valve may be repacked while it is under full
pressure. CAUTION: This is dangerous and could result in serious injury. It is not
recommended by NIBCO. In addition, standards organizations, and governing societies
today do not encourage valves to be repacked while the valve is transmitting a fluid at
full pressure and/or temperature.
The stuffing box is formed by the annular space between the stem and the bonnet and is
filled with non-asbestos packing. The packing is compressed in the stuffing box by a
gland bushing and/or the packing nut draws down against the packing by turning the
packing nut clockwise.