LNGターミナルにおけるゲートバルブのTOVへの置き換え方法

You see many LNG Terminals stop using gate valves. They now pick トリプルオフセットバルブ（TOV） instead. This change happens because TOVs last longer. TOVs also work better in hard situations. The special triple offset shape helps seal better. The metal-to-metal design keeps the disc from rubbing the seat. TOVs also do well in very cold LNG transfer systems. At JHバルブ, we have pioneered this transition for major terminals, delivering solutions that enhance safety and reduce lifecycle costs.

Here are some main features:

You need to know the reasons and steps for this change. This helps you make smart choices.

Why LNG Terminals Switch to TOVs

Gate Valve Limitations

Gate valves have problems in LNG Terminals. They have many sealing points. Each point can start to leak, especially when it is very cold. The body and actuator can get bigger or smaller at different speeds (thermal expansion/contraction). This causes stress from the temperature changes. Over time, this stress can make the valve break more than other valves.

When you use ゲートバルブ in LNG, you face some problems:

• You need no leaks, even with high pressure and very cold temperatures.
• The valve must work with both liquid and gas phases.
• The valve must still work when pressure and temperature change fast (Thermal Shock).
• You need a design that keeps the actuator safe and stops liquid from getting trapped in the body cavity (Cavity Relief).

These problems make gate valves not as good for modern LNG Terminals. You may have to spend more time and money fixing leaks or changing broken valves.

Gate valves in LNG service break more often than other valves. Their design makes them not as good when you need a tight seal and for them to last a long time.

TOV Advantages in LNG

Triple offset valves (TOVs) fix many problems you have with gate valves. The special triple offset shape gives a tight seal. The disc does not rub the seat, so there is less damage. This means the valve lasts longer and you do not need to fix it as much.

Here are some things about TOVs that help in LNG Terminals:

You also get these good things with TOVs:

• Better sealing because of the three-offset shape.
• Can handle big pressure changes and still work well.
• Less chance of damage from bubbles or fast-moving liquid, so you do not have to fix it a lot.

The triple offset butterfly valve works well even when it is very cold. You can trust it when pressure changes fast or when you need to stop leaks. This is why more LNG Terminals pick TOVs now. For more details on flow direction, check our guide on TOV Flow Direction.

The industry is picking TOVs because you need safer and better valves. Many countries want clean energy and are making their LNG places better. This makes LNG Terminals use new valves like TOVs for better work and safety.

Replacement Process in LNG Terminals

Planning and Assessment

You need a clear plan before you replace a gate valve with a TOV. Start by checking the type of gate valve you have. Look at the material of the valve, seat, and disc. Make sure these match the needs of your LNG Terminals. Finish all welding work before you install the new valve. Let the flange cool down to room temperature. Clean the pipe to remove any dirt or debris. This step helps you avoid problems later.

You should also check the alignment of the valve and the flange. If you do not align them, you may have leaks or damage. When you install the valve, tighten the bolts in stages. This gives you an even seal. After you install the valve, operate it several times. This test checks if the valve moves smoothly. You must also test the valve in the field. Make sure it can hold the pressure you need. Plan for regular maintenance. Cycle the valve every month and release system pressure before you do any work.

Step-by-step planning checklist:

1. Check the material of the old gate valve, seat, and disc.
2. Finish all welding and let the flange cool.
3. Clean the pipe to remove debris.
4. Align the valve and flange (Check Flange Ratings).
5. Install the valve and tighten bolts in stages.
6. Operate the valve several times to check movement.
7. Test the valve for pressure holding.
8. Plan for monthly maintenance and safe pressure release.

TOV Selection Criteria

You must pick the right TOV for your LNG Terminals. Look at the technical details. The valve must meet international standards. This keeps your system safe and reliable. The TOV should work in very cold and normal temperatures, from -196°C to +80°C. It must handle high pressure and sudden temperature changes. The actuator, which opens and closes the valve, should work well in cold conditions.

Pick a TOV that matches these needs. This helps you avoid problems and keeps your LNG Terminals running well. Learn more about Cryogenic Valve Selection.

Safety and Preparation

You must focus on safety before you start the replacement. Use a valve design that can handle thermal shock. This prevents the valve from breaking when temperatures change fast. Check the seals and seats for wear. If you find damage, fix it before you install the new valve. Use lubricants that work in very cold temperatures. This keeps the valve moving smoothly. Do not over-tighten bolts or move the valve too fast. This can cause stress and damage.

Tip: Always inspect and maintain your valves before and after replacement. This step helps you find problems early and keeps your system safe.

Gate Valve Removal

You need to remove the old gate valve with care. First, make sure the system is not under pressure. Wear the right safety gear. Use tools that fit the bolts and nuts. Loosen the bolts in stages to avoid stress on the pipe. Lift the valve out slowly. Check the flange and pipe for damage or debris. Clean the area before you install the new TOV.

TOV Installation

You can now install the TOV. Align the valve with the flange. Make sure the gasket is in place. Tighten the bolts in stages, using a cross pattern. This gives you an even seal. Connect the actuator and check that it works. Move the valve open and closed a few times. This test checks for smooth movement. If you see leaks or problems, fix them before you move on. For installation tips, read our TOV Installation Guide.

Testing and Commissioning

You must test the new TOV before you use it in LNG Terminals. Fill the system and check for leaks. Test the valve at the pressure you need. Open and close the valve several times. Watch for smooth movement and a tight seal. If the valve passes all tests, you can start normal operations. Plan for regular checks and maintenance. This keeps your system safe and working well.

Note: Good testing and regular checks help you find problems early. This step saves you time and money in the long run.

Technical Factors

System Compatibility

You need to make sure the new TOV fits your LNG system. TOVs are smaller and lighter than gate valves. This makes it easier to put them in, but you may need spacers if the face-to-face dimensions differ. You can often use the same spot as before. TOVs work with both liquid and gas in LNG. They do well with high pressure and quick temperature changes. Always check if the valve lines up with the pipeline. This helps stop leaks and damage.

Tip: Look at your system drawings before you start. This helps you see if you need to change anything.

Material Requirements for LNG

LNG needs special materials for valves. Valves must work in very cold places. You need metals that stay strong and do not break (avoid 脆性破壊). Most LNG valves use stainless steel, nickel alloys, or titanium. These metals do not rust and keep their shape in the cold.

Look for these things in your TOV:

• Austenitic stainless steels like 304, 304L, 316, and 316L work well when it is cold.
• Extended bonnets keep the packing above freezing. This helps the valve work better.
• Pressure relief parts stop leaks if the pressure gets too high.
• Stem seals use both soft and hard materials for a tight seal.
• Materials must handle shrinking from cold and weld easily.
• The valve must meet BS 6364 rules for cryogenic safety.

簡単な比較を以下に示します。

メンテナンス

You will need to fix TOVs less often. The non-rubbing design means less damage. You do not have to fix leaks as much. TOVs use a built-in seat for a tight seal. This keeps LNG from leaking out. You save money because TOVs last longer and cost less to put in. Gate valves need more repairs because they are more complicated. TOVs handle shrinking and growing from cold better, so you see fewer problems.

Note: Regular checks and easy fixes keep your TOVs working well for a long time.

Challenges and Solutions

Common Obstacles

You may face several challenges when you replace gate valves with TOVs in LNG terminals. The first challenge is system downtime. LNG operations need to run all the time. Any shutdown can cost a lot of money. You also need to handle very cold temperatures. Not all valves work well in cryogenic service. Sometimes, you find that the old pipeline does not match the new TOV (face-to-face dimensions). This can cause leaks or fitting problems.

You may also worry about safety. LNG is very cold and can be dangerous. If you do not follow the right steps, you can have leaks or even accidents. Another challenge is training. Your team may not know how to use or fix TOVs. You need to teach them new skills. Some operators also worry about the cost of new valves and actuators. They want to know if the investment will pay off.

Tip: Always plan for extra time and resources when you switch valve types. This helps you avoid surprises.

Overcoming Issues

You can solve these problems with smart planning and the right tools. Many LNG terminals use intelligent design and maintenance for their flow control systems. This makes your work safer and more efficient. You should choose TOVs that are made for LNG service. These valves are built for tightness and safety. The world’s largest LNG project used over 2000 triple offset valves. This shows that TOVs work well, even in tough conditions.

You can also pick electric actuators. These reduce emissions and can save money over time. Some sites use high-capacity pilot-operated relief valves. These valves help cut product loss and lower emissions. One facility saved over $260,000 in installation costs by using these valves. For emergency shutdowns, you can use pneumatic actuation systems. These close valves quickly and keep your site safe.

• Train your team on new valve types and systems.
• Use regular checks and smart maintenance to catch problems early.
• Pick valves and actuators that match your system’s needs.

Note: When you use the right solutions, you can make your LNG terminal safer, more reliable, and more cost-effective.

Benefits After Replacement

Operational Performance

You see a big change in how your system works after you switch to triple offset valves. The valves open and close faster. You get a tighter seal, so you stop leaks. The valve handles both liquid and gas without trouble. You can trust the valve to work in very cold places. The system runs smoother and you spend less time fixing problems.

Key operational benefits:

• Quick valve response
• Reliable sealing in cryogenic service
• Smooth operation with liquid and gas
• 故障の減少

Tip: When you use TOVs, you help your team work faster and safer.

Safety Improvements

You make your site safer when you use TOVs. The valve design stops leaks, even when pressure changes fast. You lower the risk of accidents because the valve does not get stuck. The metal-to-metal seal works well in cold and high-pressure jobs. You protect your workers and equipment.

Always check your valves for damage. Regular checks keep your LNG Terminals safe.

Cost and Maintenance Savings

You save money when you use TOVs. The valve lasts longer, so you buy fewer replacements. You spend less on repairs because the valve does not rub and wear out. The smaller size makes installation cheaper. You use less energy to operate the valve (lower torque).

Ways you save:

1. Fewer valve replacements
2. Lower repair costs
3. Cheaper installation
4. Less downtime

You can use your budget for other upgrades when you spend less on valve maintenance.

You now know the key steps for replacing gate valves with TOVs in LNG terminals. You must plan, select the right materials, and follow safety checks. TOVs give you better performance, safer operation, and lower maintenance costs. JHバルブ is ready to support your transition with engineering expertise and high-quality manufacturing.

Best practices for your upgrade:

• Train your team on TOV use.
• Schedule regular valve checks.
• Choose valves that meet LNG standards.

Take time to review your system. You can find ways to improve safety and save money.

よくある質問

What is a triple offset valve (TOV)?

A triple offset valve uses three offsets to help the disc seal tightly. You get a metal-to-metal seal that does not rub. This design works well in very cold LNG systems.

Why should you replace gate valves with TOVs in LNG terminals?

You should replace gate valves because TOVs last longer and seal better. TOVs handle cold temperatures and pressure changes without jamming or leaking. You spend less time fixing leaks.

How do you know if a TOV fits your LNG system?

Check the size and pressure rating of your pipes. Make sure the TOV matches these numbers. Look at your system drawings. Note that TOVs are often shorter (face-to-face) than gate valves, so you may need spool pieces.

What maintenance do TOVs need?

You should check TOVs every month. Look for leaks or damage. Move the valve open and closed a few times. Clean any dirt you find. Regular checks help your valve last longer.