Обратный клапан NAB C95800 Globe: принцип действия, материалы и руководство по выбору
A NAB C95800 globe stop-check valve combines
manual shutoff and flow regulation with automatic protection
against reverse flow. Its nickel aluminum bronze body makes it
suitable for selected seawater, marine cooling-water and shipboard
utility systems.
manufactured according to the project specification.
What Is a NAB C95800 Globe Stop-Check Valve?
A globe stop-check valve uses a globe-pattern body and a movable
disc to provide three functions: manual isolation, controlled flow
regulation and automatic reverse-flow prevention.
When the handwheel is set to the open position, forward pressure
lifts the disc and allows the fluid to pass through the valve. If
the flow reverses, the disc moves back toward the seat and helps
prevent backflow. Turning the handwheel downward forces the disc
onto the seat for positive isolation.
This design can replace a separate globe valve and check valve in
some piping systems. However, flow direction, pressure drop,
installation position and disc movement must be confirmed before
ordering.
Globe Valve vs. Globe Stop-Check Valve
| Особенность | Standard Globe Valve | Globe Stop-Check Valve |
|---|---|---|
| Manual shutoff | Yes | Yes |
| Flow regulation | Suitable with correctly selected trim | Possible, depending on disc and stem design |
| Automatic non-return action | No | Yes, when the valve is set open |
| Typical function | Isolation and throttling | Isolation, throttling and backflow protection |
Why Use ASTM B148 C95800 Nickel Aluminum Bronze?
UNS C95800 is a cast nickel aluminum bronze containing copper,
aluminum, iron, nickel and manganese. ASTM B148 includes
requirements for aluminum-bronze sand castings such as UNS C95800.
For marine valve bodies, C95800 is commonly considered because it
combines useful mechanical strength with corrosion resistance in
many seawater environments. It can also provide useful resistance
to erosion and cavitation when the valve is correctly designed and
operated.
Material selection should not be based on the alloy name alone.
Seawater velocity, temperature, aeration, sulfide contamination,
stagnant conditions, chlorination and galvanic contact with other
metals must also be evaluated.
Technical references:
Copper Development Association C95800
и
ASTM B148
.
Типичные области применения
- Shipboard seawater piping systems
- Marine cooling-water lines
- Offshore equipment-cooling systems
- Marine firewater networks
- Pump discharge and equipment-protection lines
- Selected condensate and utility-water systems
- Selected low-temperature steam service after technical review
For steam service, the specified pressure-temperature rating,
packing, seat, trim material and applicable design code must be
checked. Pressure class alone is not enough to confirm suitability.
Available Project Configuration
WDL Valve supplies
NAB C95800 globe valves
with project-selected connections, trim and operating methods. A
globe stop-check version should be confirmed against the
purchaser’s datasheet and approved manufacturing drawing.
| Пункт | Available Project Selection |
|---|---|
| Body material | ASTM B148 C95800 or project-specified NAB grade |
| Функция | Isolation, throttling and automatic non-return action |
| End connection | С фланцами, резьбой, для сварки в муфту или встык |
| Эксплуатация | Handwheel, gearbox, pneumatic or electric operation, depending on the stop-check mechanism |
| Проектные условия | API 623, BS 1873, ASME B16.34 or project specification |
| Documentation | Material certificates, pressure-test reports, inspection records and approved drawings |
ASME B16.34
covers areas including pressure-temperature ratings, materials,
dimensions, examination, testing and marking for applicable valve
constructions.
Important Selection Considerations
1. Confirm the flow direction
A globe stop-check valve normally has a specified inlet and outlet.
Installing it against the marked flow direction may prevent the
disc from operating correctly.
2. Check the pressure drop
The globe-pattern flow path usually creates more resistance than a
straight-through gate or ball valve. Required flow coefficient,
normal flow rate and permitted pressure drop should be provided.
3. Review installation orientation
The disc must move freely for automatic check action. Horizontal
or vertical installation should follow the approved manufacturer
drawing.
4. Select compatible trim
Body, disc, seat, stem, packing, fasteners and adjoining piping
should be reviewed together. Incorrect material combinations may
increase galvanic corrosion or lead to premature seat damage.
5. Define shutoff requirements
The required leakage class, seat construction and test standard
must be specified. Do not assume that every globe stop-check valve
provides the same shutoff performance.
What Information Should Be Included in an RFQ?
Providing complete operating information allows the manufacturer
to verify the C95800 material and stop-check mechanism.
- Valve size and pressure class
- End-connection and flange standard
- Fluid name and complete chemical composition
- Рабочее и расчетное давление
- Рабочая и расчетная температура
- Normal, minimum and maximum flow rate
- Required flow coefficient or permitted pressure drop
- Required shutoff performance
- Installation position and flow direction
- Body, trim, packing and fastener materials
- Testing and third-party inspection requirements
- Drawing, certificate and document requirements
Common Selection Mistakes
- Treating it as a normal check valve:
stem position and disc movement directly affect automatic operation. - Ignoring pressure loss:
a globe-pattern valve normally produces a higher pressure drop
than a straight-through valve. - Only stating “seawater”:
water temperature, velocity, chlorination, sulfides and stagnant
periods can change material suitability. - Mixing incompatible materials:
the body, trim, fasteners and piping should be reviewed as one
complete galvanic system. - Not checking orientation:
flow direction and installation position must follow the approved
drawing.
Часто задаваемые вопросы
Can a globe stop-check valve replace two separate valves?
It can combine isolation and non-return duties in one body when the
system design, pressure drop and project specification permit it.
Final approval should come from the piping system designer.
Is every NAB C95800 globe valve a stop-check valve?
No. A standard globe valve does not automatically prevent reverse
flow. The valve requires a disc and stem arrangement specifically
designed for stop-check operation.
Is ASTM B148 C95800 suitable for every seawater condition?
No material should be approved from the alloy designation alone.
Water chemistry, temperature, velocity, contamination, galvanic
contact and operating pattern must be evaluated.
Can a C95800 globe stop-check valve be used for steam?
It may be used when the body rating, trim, packing, seat,
pressure-temperature limits and applicable design code match the
steam conditions. Written manufacturer confirmation is required.
What must be confirmed before ordering?
Confirm the complete datasheet, flow direction, installation
position, face-to-face dimension, flange dimensions, materials,
shutoff criteria, testing requirements and documentation package.
