Butterfly Valve Leakage: Inspect, Avoid, and How to Fix

Home Butterfly Valve Leakage: Inspect, Avoid, and How to Fix
29/01/2022
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Butterfly Valves

Source: Depositphotos

When it comes to using butterfly valves, leakage issues and how to deal with them is one of the most frequently asked questions by the plant staff. We know how irritating it is to have an issue like this, mainly if the item was recently bought and you expected it to work perfectly. Even a few millimeters of leaking can lead to huge losses. Also, make sure to buy one from a leading industrial valve manufacturer.

Don’t be afraid if this is the situation; several butterfly valve issues can be readily fixed. However, some leakage issues may need a total valve repair, so keep in mind that no two cases are alike.

Expert companies work towards refining their design and production methods for their high-performance butterfly valves. However, certain issues still persist. We’ve reviewed various methods for repairing a leaky butterfly valve in this article.

Before choosing how to repair a leaky butterfly valve, consider the following issues. This will help you decide whether repairing the leak is even needed or if it will cost you unduly large sums of money that are not worth it.

Please Check Beforehand

Proper Butterfly valve

Source: Image

Proper Butterfly valve type

Butterfly valves such as concentric butterfly valves come in a variety of styles, including lug style, wafers, and double-flanged, as well as different materials. Check that you’re using the correct type for your project. Some valves are designed to handle grit and sand, whereas others are designed to handle gasses. Make sure you follow the owner’s manual on how to use it. 

Leakage tolerance

A butterfly valve has maximum leakage limits, which vary depending on the design. While no leakage might sound fantastic, it is not usually the case, and also, many butterfly valves can leak at a certain point.

This is especially the case when the channel is a gas like helium.  Per FCI 70-2, metal-seated butterfly valves have permitted leaking rates (Class VI). Bubble snug cutoff valves are the valve family’s most robust sealing valves, yet they also allow a sufficient number of bubbles to pass through.

Operating pressure limit

One of the most prevalent reasons valve leaks create severe losses in the plant is a failure to stick to maintenance plans and procedures. Your plant’s valves should be tested regularly and repaired, if needed. This is to detect whether the leaking is severe enough to cause damage to the device. This is also done to see if the stem has broken or if the seat has cracked.

Test the valve position to see if it is suitable. You can find this information in the owner’s manual. If a butterfly valve is fitted in a horizontal tube built for a vertical pipe, its y-axis will be heavily loaded. Leakage might occur if the vessel is positioned wrongly.

Common Butterfly Valve Leakage And solution

Gate valve

Source: Instrument Forum

Butterfly valves or gate valves are often used as shutdown or flow control valves. In its closed state, it acts as a shutdown valve, blocking the flow of fluid and preventing leaks. In such a condition, it should not only tightly cover the pipe and rail to avoid inner leakages within the pipe network but also reduce fleeing leakages that escape from its valve to the outside.

Butterfly valves leak for a variety of causes. This could be one of the following options:

  • The valve seat is dirty, or the valve stem and disk are rusty.
  • The seat is scored.
  • The seal has been broken.
  • Inadequate actuator motion.

The following are some of the most common reasons for leaking into the atmosphere:

  • Stem packing deterioration
  • The gasket between the valve body and the bonnet has been damaged.

If possible, try one of these methods first.

There can be several possibilities for a leaky control valve, and there is no certainty that one issue can be handled with a broad remedy, but we give the most common problems with a few treatments you can do to fix the problems here.

If there is a leak between both the actuator and the butterfly valve, cleanse the packing hole and change the packing as needed. If the valve is difficult to actuate or work, apply lubricant to the actuator and wipe and replace the seat and stem. Moreover, while tightening the bolts, use thread vault or Loctite.

If the butterfly valve cannot open or close properly and leakage happens, use an air hose to directly blast air into the pneumatic system to see if it runs typically. If it is okay, the control valve may be failing. Change the control valve. 6 kg of airflow is needed. The actuator should be replaced. Resetting the air actuator end stop position should resolve the issue.

If the automated valves do not open, test the power supply; replace any burned or damaged fuses; and reset the device. Check the actuator’s signal peptide and then replace the existing motors, switches, or solenoid valves.

If there is still a leakage in the seat seal, ensure that the valve is tightly sealed, that the actuator locks at load torque, that the valve is open/closed under force, and that the torque is increased. Repair the seat seal if the valve keeps leaking. 

If the leaking continues in a more severe case, a more analytical study should be done to solve the problem. When replacing the butterfly valve, check the quality of the new parts. Make sure to use only the best quality materials. 

Leakage between Actuator and Valve

Actuator and Valve

Source: Image

Description

When you find score markings on the disc’s surface, this could indicate that the disc was not correctly fitted from the beginning. When closing, this gives a scraping effect on the lining seat layer, resulting in leaks. Solid particles flying into the air may have caused repeated hits on the leaky surface to make the problem worse. This finally limits the butterfly valve’s life span.

If the level of leakage exceeds the fixed limit and the seat has many flaws, the butterfly valve seat liners should be changed. Ensure that the seat (O-ring) produces a high pushing motion in your setup for tight sealing. To prevent mismatch, ensure the actuator end-stops are placed right this time.

The pneumatic actuators have now been compact for tight mounting settings and low air usage. The gap-free shape gives extra cleanability and meets the utmost hygiene standards.

Torque max at both ends allows for use on both normally closed and normally open valves. Metallic grips ensure that the disk is precisely positioned. There are two types: air-to-spring and air-to-air.

Possible cause

Some fitted butterfly valves are oversized or undersized, which could be the source of the leak. Make sure the valves you place are the right size and volume grade for the purpose. Any mismatch upon installation may change the valve’s force rating ability, resulting in valve leakage.

How to fix

If the broken seat can be repaired, a small actuator change can level the disc and prevent the leak.

#1 Take out the Actuator

To begin, disconnect all power sources from the pneumatic or electrical actuator. After that, loosen the bolt nuts and screws.

#2 Put Together the New Seat

Replace the seat if you see it is broken. Replace the disk first, then the seat. Before turning the disc into the open spot, detach the nut and its cap. Squeeze the seat to separate it from the covering, then gently peel it off the spindle.

Unclog the stem as well as the seat before installing the new seat. Put the stem into the seat slot with the butterfly valve open. Then, in its open position, wedge the disk and seat by two flanges. After that, replace the bushing.

Run a visual check to ensure that the proper closing torques are used.

#3 Reinstall and fine-tune the Actuator

Put the actuator once the bolts have been installed, and check that the butterfly valve opens and closes smoothly with the allowed resistance. Check that the proper valve body type, liner, and nut alignment is used. Lastly, attach the power supply or pressurized air and check the butterfly valve to see if it works properly.

Shut-off Failure

Shut off Failure

Source: Image

Description

Shut-off valves, which are used in various areas, provide for the safe operation of compressed gas in pneumatic systems. A shut-off valve, for instance, placed over a dead leg flow, lets any water flow out at that place so that repairs can be done.

Possible cause

The primary cause of shut-off valve breakdowns (seizing) is aging internal parts such as rubber gaskets. Many plumbing parts and household appliances in your home need a shut-off valve that lets you switch off the water fast and efficiently in the case of a plumbing issue. 

How to fix

Plumbing line shutoff valves below toilets or even under basins can spend years without it being switched off and restored. Lack of activity can lead neoprene gaskets to become stiff or coated with mineral deposits, losing their ability to stop leaks. Repairing the valve is often quite simple if you know what to do.

#1 Adjust the Packing Nut if needed.

To plug a leakage around the screw, twist the sealing nut on the sewage shutoff valve one-eighth degree clockwise.

Tie linen or sticky tape around the forceps’ jaws to secure the nut’s finish. To avoid ruining the water mains, use light, constant pressure.

#2 Remove the Shutoff Valve.

Remove the shutoff valve while keeping the toilet and supply routes in place. Using a wipe, clean the washers. Try flexing the neoprene to have it flexible again.

Avoid clogging inside the shutoff valve by not using pipe grease or plastic wrap on the valve stem’s screws.

Before removing the toilet shutoff valve, shut off the primary water supply.

New screws for the correctly sized shutoff valve are found from plumbing supply shops and larger hardware stores that keep an extensive stock of repair items.

If this does not stop the leak, you will have to replace the entire valve.

Leaks when closing

Description

Because cut-off (shut-off) valves are hardly used, the gasket within the valve might harden or become coated in mineral wealth with time. Once you close and reopen the valve, the gasket on the valve stem might not always seat well, creating leakage around the valve seat screw.

Possible cause

Some fitted butterfly valves are oversized or undersized, which could be the source of the leak. Ensure the valve you place has the right size and volume rating for the work. Any mismatch during setup can change the valve’s pressure rating capabilities, resulting in valve leakage.

How to fix

  1. Turn off the primary water supply to the faulty valve.
  2. Unscrew the cap nut on the leaking shut-off valve using a torque wrench.
  3. Take the screw back to reveal the twisted spindle of the valve.
  4. Cover the spindle in Teflon wrapping, and hand-tighten the cap nut back into position.
  5. Lock the nut with the tool, and don’t ever over-tighten it.
  6. Reopen the pump water valve.
  7. Now, carefully open the mended shut-off valve and ensure it is no more leaking.

Leaking from seat seal

Description

The flow of fluid through a valve set to the ‘off’ position is known as valve leakage. The impact of valve leakage is regulated by what the valve controls. Under those settings, Class III valves allow no more than 0.1 percent leakage; they might need soft valve seats or split metal surfaces.

Possible cause

When no liquids are present to lube the seal, it becomes dry, causing extra frictional heat. The seal will melt or burn and then become cracked, allowing fluid to flow due to the pressure. Merely a few seconds of dry operation can result in heat splits or burns, resulting in a leaking motor shaft seal.

How to fix

  1. To use a wrench, remove the supply line from the shutdown valve. 
  2. Check that the valve is shut and that the toilet is empty.
  3. Peel off the curved covers that top the closet screws, then detach the hex nuts with a tool.
  4. Pull the toilet by the seat, not just the tank, and place it on an old sheet or cardboard sheet.
  5. Remove the old wax seal from the closet lip. It is worth noting that a portion of the flange has been broken off.
  6. After releasing the nuts that hold the closet flange to the ground, put a repair strap beneath it.
  7. Make sure the new waxed seal is placed on the closet flange. Take note that both closet nuts are in position.
  8. Attach the new water-supply tubing to the base of the sewage tank’s attached fill-valve stem.

Leaking from Stem

Description

The stem valve might be fragile and broken with time, increasing the chance of air seeping through it. Once the stem valve fails, the damaged tire loses its capacity to keep air. The valve should be changed in both cases.

Possible cause

A valve stem leak might act similarly to a crack, slowly letting air escape through the bottom of the valve body. Leakage in the valve stem can arise for various reasons, the most common of which are road chemicals and rust.

How to fix

1. Confirm whether or not the valve stem is leaking.

Of course, you must verify whether or not your valve stem is leaking. You can do so by wiping a solution of water and dish detergent over the open valve stem with your fingers. If you notice bubbles forming, the air is escaping from the valve.

2. Take Care of the Required Tools.

You will need a few things for this repair process. You will need a valve stem tool (formed like a “+”) and a new valve core, both of which are affordable. These products should be easily accessible at any local auto supply store.

3. Take off the tire.

After verifying that the valve is faulty, the tire should be taken and deflated. While it is possible to undertake these minor repairs while the tire is still tied to the car, it is advisable to detach it as it will be easier and safer. Once the tire has been taken and inflated, use the valve stem device to detach the valve and replace the old stem.

Keep in mind that you must thoroughly empty the tire when removing the existing core, as any air inside it can allow the core to blast out and possibly injure any part of your body. It’s also a good idea to use safe eyewear.

4. The Valve Stem should be cleaned.

Use the tapering edge of the valve core tool to wipe the valve stem, making sure to keep the area free of dust and dirt. If the main core screws are rusted, use the tapping end of the valve core tool to polish the inside screws of the valve stem. Moreover, now use a valve stem cover to keep dirt away, which can be the source of the issue in the first place. Remove any obstacles from the region around the valve and within the tire.

5. Install the updated core.

To complete this stage, use a valve stem device. To put in a new core:

  1. Use the same side of the tool used to remove and replace one.
  2. Adjust by hand, but don’t over tighten it or break, causing the substitute valve to leak.
  3. Remove the valve cap and re-inflate your tire after fitting.

Working Condition for Butterfly Valve

Butterfly valves or check valves  come in a variety of styles, such as quick cut-off as well as constant adjustment. Companies like Dombor produce pneumatic and electric butterfly valves. They are often used for low-pressure, large-diameter fluid and gas pipes. It is suitable for low-pressure drop situations, flow control is needed, and the open or closed needs are fast. Typically, the temperature is below 300 °C, and the pressure is below 40 kg (butterfly valves, like home ones, use low pressure). CL600 is a rare achievement). The channel is mainly used for gas and water, and it is not taxing. It is also possible to use a grainy medium.

Water, condensation, flowing water, wastewater, seawater, wind, gas, fluid natural gas, dry powder, dirt, fruit pulp, and mixes with suspended solids are all media that the butterfly valve may carry and control.

Storage Condition for Butterfly Valve

The dual plate check valves should be stored on the floor in a tidy, dry indoor environment. Protect the valve against excess heat and humidity and extreme dust, wetness, vibrations, deflections, sunshine, and ozone—temperature: under 25°C storage, above 0°C preferably below 15°C.

Maintenance Tips

After working in multiple settings for an extended period, butterfly valves such as high-performance butterfly valves require frequent repair and maintenance. Minor repairs, moderate repairs, and extensive repairs are the three types of general maintenance.

The pipeline’s ecological factors determine the exact analysis. Since different industries demand varied repair and maintenance methods. For instance, in petrochemical company pipeline repair, the pipeline pressure must be less than PN16MPa, and the average temperature must be less than 550°C. Various chemical and physical pipeline transit mediums need specific maintenance conditions.

You should maintain butterfly valves to avoid rusting.

A lube oil fitting is located at the top of the valve. This may go unnoticed when the valve comes. Apply oil to the valve’s steam regularly until the extra grease falls.

For maintenance, you can use lithium-based lubricant in the gearbox.

To readily clean all valve sections, use any silicone-based product/lubricant. Also, rotate or cycle the butter valve once each month if you don’t use it often.

The Bottom Line

Butterfly valve separation to avoid leakage is impossible to happen. The best way to extend the life of your butterfly valve is to check it regularly and do regular maintenance. Also, deal with the leakage as soon as possible. If needed, “kill” the line to clear the wrapping and valve parts of any dirt. For more such information, you can contact us.

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