Cast Steel Pressure Seal Valves - Overview
Class
600 - 2500
Class
600 Venturi Design
Class
600 - 2500
Class
600 - 2500 Non-Return
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Class
600 - 2500 Horizontal
Class
600 - 2500 Swing Check
Class
600 - 2500 Tilting Disc
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Design
and Construction
Powell
Pressure Seal Valves are intended for high pressure,
high temperature applications in all types of fluid
except where severe coking is a factor.
The
design and materials selection provide excellent service
in fossil and nuclear steam generating stations, industrial
and chemical plants, and refineries.
The
Powell design Pressure Seal Valves provide the most
efficient flow passage and sealing features possible
resulting in significant weight savings, ease of installation
and maintenance features.
Manufacturing
and quality assurance procedures include extra controls
on dimensional, non-destructive examination and testing
of critical areas such as the gasket seating, welding
end and stellited seating surfaces.
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1.
Accurately machined Acme threads prolong the life of the
stem and bushing.
2.
Tapered
roller bearings for ease of operation.
3. Lilting lugs facilitate handling the valve during
erection and maintenance. Also provides means for supporting
the weight of the valve.
4. Swing eyebolts and gland shelves facilitate
repacking.
5. Inner row of studs establish the Initial seal
of the Pressure Seal Joint.
6. Outer row of studs secures the yokearm to the
body,
7. The bonnet joint remains tight under all operating
conditions as the sealing pressure Is always many times
greater that the pressure of the fluid in the line, thereby
eliminating leakage. The higher the Internal pressure,
the greater the sealing pressure.
8. Streamline contour of body simplifies application
and reduces cost of insulation, and effects marked savings
in space and weight.
9. Stellited back seat area provides accurate guiding
of stem.
10. Streamlined passage makes possible maximum
flow with minimum turbulence.
11. Stellite faced flexible "H" type wedge prevents
sticking due to temperature changes and pipe line stresses.
12. Seal rings are Stellite faced and securely
welded in place.
Pressure
Seal Valve Components
BODY
- Flow areas are designed for minimum turbulence and
pressure drop. Casting and forging quality requirements
are considered in the design of Powell Pressure Seal
Valves.
BONNET
- Ample stuffing box and stellited stem guide and back
seat shoulder are provided for accurate guiding of the
stem and back seating.
WEDGE
(Gate Valves) - Flexible wedge design on 4" and
larger sizes provide flexibility to prevent sticking.
Wedges are stellite faced and have machined guides for
control of alignment during valve operation.
DISC
(Globe & Check Valves) - Globe and check type discs
are accurately fitted and guided to minimize vibration.
Seating surfaces are stellited One piece stem and disc
design are furnished on larger sizes.
SEAT
RINGS - Seat rings are stellite faced, accurately fitted
and seal welded in place.
YOKE
DESIGN - Studs fasten the yoke directly to the valve
body. The bolting and internal design features eliminate
heavy clamp rings and provide rigidity, accurate alignment
of the valve internal parts and operating mechanism.
Lifting lugs on large size valves aid in installation
and maintenance operation.
STEM
- Threads are accurately machined. Packing area is polished
to reduce stem friction and packing wear.
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Delta
Pressure Seal Design
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Standard
Pressure Seal Design
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Delta Seal Design is used in valves for pressures
2500 pound and higher and services which have drastic
temperature variations. This exclusive double gasket
design provides three sealing surfaces that contract
and expand uniformly with the valve body eliminating
body leaks. The 5° seat taper eliminates surface
contact and possible damage to the gasket and seating
surface of the valve during removal of the gasket.
The Delta Seal Gasket can be easily removed for
valve maintenance, reducing downtime appreciably.
This results in more reliable operation of Powell
Pressure Seal Valves. |
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The
segmental thrust ring absorb all the thrust applied
by internal pressure. A hardened stainless steel
protective ring prevents deformation of the top
surface of the soft metallic gasket. The 5°
seat eliminates surface contact and possible damage
to the gaskets and internal surface of the valve
during removal of the gasket. The gasket can be
removed freely without damaging the sealing surface
of the body. The gasket seat surface in the body
may be lapped, if required. |
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