русский
简体中文
In many industrial systems, controlling the movement of liquid or gas is a daily task. Valves make this possible by opening, closing, or adjusting flow. Among different valve types, the trunnion mounted ball valve is often chosen for large pipelines and heavy duty conditions.
A ball valve uses a round ball with a hole in the center to control flow. When the hole lines up with the pipe, fluid passes through. When the ball turns, the hole is blocked and flow stops. This turning action only needs a quarter turn, which means ninety degrees.
The word trunnion refers to how the ball is held. In this design, the ball is supported by two shafts, one at the top and one at the bottom. These shafts keep the ball steady. Because of this support, the ball does not move much when pressure in the line becomes strong.
The main parts of a trunnion mounted ball valve include:
Are Trunnion Mounted Ball Valve Bidirectional?
Can this kind of valve control flow from both sides? In real projects, flow direction is not always fixed. During cleaning, testing, emergency operation, or system change, liquid or gas may move in the opposite way. If a valve cannot handle this, leakage or safety risk may appear.
So the idea of bidirectional use is not only technical. It is closely linked to daily operation, maintenance cost, and safety control.
What Bidirectional Really Means
Bidirectional means the valve can stop flow and seal properly no matter which side the pressure comes from. In simple words, it can work the same way even if inlet and outlet change roles.
Some valves are built mainly for one way flow. They seal well only when pressure comes from a certain side. If pressure comes from the opposite side, sealing may become weak.
Others are designed so that pressure from either side can help create a tight seal.
For users, the difference is very important.
General Answer for Trunnion Mounted Ball Valve
In many common designs, a trunnion mounted ball valve can work in both directions. This is mainly because of two structural ideas:
When pressure comes from one side, it pushes the seat on that side closer to the ball. This helps close the gap and stop flow. If pressure comes from the other side, the same thing happens on the opposite seat.
So in normal designs with two moving seats, bidirectional sealing is possible.
However, not every product on the market is built in the same way. Some are designed mainly for one direction, based on special system needs.
How Sealing Changes With Flow Direction
To understand this clearly, imagine pressure coming from the left side.
Now imagine pressure comes from the right side.
Because the ball itself does not move much, sealing depends on how the seats react. This moving seat design is the key reason why many trunnion mounted ball valves support two way use.
Single Seat and Double Seat Design
Not all trunnion mounted ball valves use the same seat structure.
Some use single moving seat
Some use double moving seat
| Type | Sealing From Left | Sealing From Right | Common Use |
|---|---|---|---|
| Single seat | Yes | Limited | One way systems |
| Double seat | Yes | Yes | Two way systems |
If a system never changes flow direction, a single seat design may be enough. But if reverse flow can happen, double seat design is safer.
Why Bidirectional Ability Matters
In many systems, flow does not always stay in one direction. Examples include:
If a valve cannot seal well in reverse flow, it may cause:
So choosing a valve that matches real working conditions is very important.
How to Know If a Valve Is Bidirectional
Do not rely only on the product name. It is better to check:
Some valves have arrows showing flow direction. This often means they are mainly for one way use. If there is no arrow, it may support two way flow, but it still needs confirmation.
Installation and Flow Direction
Even if a valve can work in both directions, correct installation still matters.
Some designs have:
So during installation:
Correct fitting helps parts last longer.
Effect of Reverse Flow on Wear
When flow direction changes often, internal parts face different force patterns. Over time this may cause:
So in systems with frequent reverse flow, maintenance should be more careful. Regular checks help find early signs of leakage.
Industries That Need Two Way Flow
Bidirectional trunnion mounted ball valves are often used in:
In these places, operation modes change often. Valves must handle different working states safely.
Double Block and Bleed Structure
Some trunnion mounted ball valves use a design with two sealing points and a middle cavity that can be released. This is often called double block and bleed.
This structure allows:
Such valves are usually bidirectional, but again, each design must be checked before use.
Simple Example
Imagine a gate between two roads. If it can only block cars from one side, then cars coming from the other side cannot be stopped. That would be unsafe.
A bidirectional valve is like a gate that can stop cars no matter which side they come from. This makes control easier and safer.
Limits and Special Uses
Even though many trunnion mounted ball valves support two way use, there are still special designs made mainly for one direction.
This may happen when:
So the design goal always comes first.
Maintenance and Inspection Tips
To keep bidirectional performance stable:
Early inspection helps avoid big repair work later.
Key Points to Remember
In real plants and pipelines, valves face pressure change, temperature shift, frequent opening and closing, and sometimes rough handling. A design that looks good in theory must also survive these challenges in practice.
What Makes Trunnion Design Different
The key idea of trunnion design is simple. The ball is supported at the top and bottom. It does not float freely. Instead, it stays in a fixed position, held by two support points.
This small change in structure leads to several real life effects:
These effects may not sound dramatic, but in long term use, they make a clear difference.
Daily Operation Experience
In real factories, operators often judge a valve by how it feels when they turn it. If a valve becomes hard to move, it usually means something inside is under too much stress.
With trunnion design:
This means operators do not suddenly find a valve becoming very hard to turn after months of use.
In large systems, this also means gear boxes or powered units do not need to fight against heavy internal force all the time.
Effect on Sealing Stability
In real use, pressure is not always smooth. It can rise, fall, or change direction. In floating ball designs, this often causes the ball to shift slightly, pressing harder on one seat.
Over time, this uneven force can lead to:
With trunnion design:
This makes sealing behavior more balanced. Even when pressure changes often, the contact between ball and seat remains more controlled.
Wear Pattern in Long Term Use
No mechanical part lasts forever. But the way parts wear can decide how long a valve can stay in service.
In many real projects, engineers have seen that:
Trunnion design helps reduce these problems because:
This does not mean no wear happens. It means wear happens in a more predictable and manageable way.
Maintenance in Real Plants
Maintenance teams often prefer designs that are easy to inspect and repair.
In real use, trunnion design offers some practical benefits:
This can reduce downtime. In large plants, stopping a system just to change a valve can be costly, so any design that reduces this need is welcome.
Energy Use During Operation
When a valve needs high force to turn, it also means more energy is needed, especially when using electric or pneumatic actuators.
With trunnion design:
Over long periods, this can help reduce running cost, especially in systems with many valves that open and close often.
Behavior Under High Pressure
In real pipelines, pressure is not only high but also changes suddenly at times.
If a ball moves under pressure:
Trunnion design avoids this because the ball is held in place. Pressure mainly pushes the seats, not the ball. This makes behavior under high pressure more controlled.
Installation in Real Conditions
In theory, every valve is installed perfectly. In real life, space is limited, pipes are not always straight, and working time is short.
A stable internal structure helps in these cases:
This does not mean installation can be careless. It means the design is more tolerant to small real life imperfections.
Use in Systems With Flow Change
Many real systems face flow change:
In such cases, pressure may come from different directions.
Because trunnion design uses moving seats and fixed ball:
This helps the valve survive systems where flow direction is not always the same.
Comparison in Real Use
| Aspect | Trunnion Design | Floating Ball Design |
|---|---|---|
| Ball movement | Fixed | Moves under pressure |
| Turning feeling over time | More stable | Can become heavy |
| Wear pattern | More even | Often uneven |
| Reaction to pressure change | Calm and steady | More sensitive |
| Long term sealing | More predictable | Depends on pressure side |
Cost View in Real Projects
At the beginning, trunnion design may cost more. But in real use, cost is not only about purchase price.
Real cost includes:
If a design reduces repair frequency and keeps operation smooth, it can reduce total cost over years of use.
Safety in Daily Operation
In many industries, safety is more important than speed or price.
Stable shut off function helps:
Because trunnion design handles pressure more calmly, it is often used where safety rules are strict.
Real Example for Easy Understanding
Think of a heavy gate in a windy area.
If the gate is only supported on one side, wind can push it hard, making it shake and wear fast. If the gate is supported at both top and bottom, it stays more stable even in strong wind.
Trunnion design works in a similar way. The ball is supported from two sides, so pressure cannot push it around easily.
When Trunnion Design May Not Be Needed
Not every system needs this design.
In small pipelines with low pressure:
Using trunnion design in such cases may not bring much extra benefit.
So the design matters most in:
Future Use in Real Industry
As industries grow and systems become larger, the need for stable and durable valve design increases.
Trunnion design is likely to stay important because:
Materials and seat shapes may change in the future, but the idea of fixing the ball firmly is likely to remain.
Trunnion design matters in real use because it changes how a valve behaves under pressure, during operation, and over long periods of service. By holding the ball in place and letting the seats handle pressure, this design reduces internal stress, keeps operation smoother, and makes wear more even.
In daily plant life, this means:
Understanding why this design matters helps users choose the right valve for their system, not just by name, but by how it will really perform after years of work.
When it comes to trunnion mounted ball valves, picking a manufacturer you can rely on matters. Naishi makes valves designed to be stable and durable, able to handle demanding industrial conditions without causing unnecessary downtime.
Working with a factory like this brings practical advantages:
A valve from Naishi runs smoothly, stays reliable over time, and reduces the effort needed for operation and maintenance, helping systems work safely and efficiently.
nce@cnnsv.com
+86-15727968392 / +86-15397375798
+86-577-67091815
+86-577-67091815
Dongou Industrial Zone, Oubei Street, Yongjia County, Wenzhou City, Zhejiang Province, China
Contact Us