The Yarway Welbond Valve has become an established stop valve for general line service in modern
high pressure power plants worldwide.
The Welbond offers the industry a value-engineered product with minimum maintenance and maximum service life resulting from
its unique in-line renewability feature. The one-piece body eliminates all pressure welds, threads, and their related problems.
The extra thickness of the Stellite seat ring eliminates seat cracking and provides for repeated renewal of the seating surface
with Yarway’s reseating tool. The disc is a Stellite investment casting.
The design of the disc reduces sealing torque for easy operation both manually and with a powered actuator. The body design
allows the disc-stem assembly to retract completely into the body, thus assuring smooth flow and a high Kv characteristic.
Removable Backseat
This design offers the greatest accessibility, thus is the easiest to maintain, especially when complete removal of the stem
packing is desired.
Because the stuffing box bushing is not fastened to the body, the entire stem, disc, and packing assembly can be jacked out
of the body by simply turning the handwheel counterclockwise after releasing the gland. No special tools or picks are required
to extract the packing.
In operation, full opening of the valve exerts an upward force on the stuffing box bushing, thus compressing the stem packing
from below—a maintenance feature frequently used to prevent steam leakage until shut-down can be rescheduled.
Threaded-in Backseat
This design offers accessibility after removal of the threaded stuffing-box bushing by means of a special Backseat Removal Tool.
It requires no seal weld removal for maintenance.
A special packing removal tool, available from Yarway, can be used to remove old packing, quickly, from fixed backseat valves. |
|
Features and Benefits
- Fastest In-Line Repair
Renewable in-line more easily and at less cost than any other valve. Captive gland bolts allow quick release of packing
gland without removal of gland nuts. "Ears" on gland prevent slipping. Stem, disc, and packing can be quickly removed
through the yoke, and the seat fully exposed for "like new" restoration.
- High Dependability
One-piece forged body without pressure welds, seal welds, pressure- containing threads or gaskets, body/bonnet joints,
or any of their related problems.
- Greater Durability
Solid Stellite disc and seat ring all but eliminates cracking. Extra thickness of the seat ring also provides enough
material to renew the seating surface over and over again.
- High Flow Capability
Generous port sizes and disc retraction well beyond that required for optimum flow. These features help to minimize
flow velocities and, therefore, decrease the erosive forces which shorten the life of the seat and disc.
- Convertible Feature
The valve is available with either a loose or threaded in backseat. The complete pre-machining of each Valve body means
one of the backseat designs can be converted to the other, simply by reassembly with alternate back-seat bushing.
|
|
