What is a tilting disc check valve?
A tilting disc check valve is a type of valve meant for preventing reverse fluid flow. The flow of fluid in the reverse direction can damage piping fixtures like pumps, and boilers or cause contamination of the fluid. The tilting disc check valve is designed with a disc as the opening and closing member. The disc is made to rotate about a pivot and it is offset from the seating plane. The disc is forced onto the seat when it closes and it lifts off the seat when it is opened. These valves close very fast because the center of gravity at the disc halves. Tilting disc check valve manufacturers also use a spring mechanism to help the valve in quick opening and closing. One of the main challenges of tilting check valves is that they are difficult to repair and also more expensive relative to other valves like swing check valve. As such, tilting disc check valve manufacturers recommend use of these valves where swing check valves cannot be used. Tilting disc check valves operate automatically and they do not need a valve handwheel or actuator common in other valves like a ball, gate, or globe valves. Tilting check valves depend on pressure difference whereby they open when there is high suction pressure and they close automatically when the suction pressure reduces or when there is a backflow of fluid.
Figure: Tilting disc check valve.
Components of tilting disc check valve
Valve body
This is the part of a tilting check valve used to contain all internal parts of the valve. The body needs to be very strong to withstand internal pressure as well as protect internal parts against impact damage. As such, tilting disc check valve manufacturers design these valves with strong metallic materials such as ductile iron, carbon steel, and stainless steel to ensure the valve body has high strength. The valve body also contains the valve ports which connect the valve to the pipe to allow fluid transmission.
Valve cover/bonnet
This is the component of a tilting check valve which is placed on top of the valve body. The bonnet/cover is connected to the valve body using bolts and nuts or by welding. The cover and body are also made of the same metallic material to ensure uniformity when being tightened.
Disc
This is the part of a tilting disc check valve that is used to open and close fluid flow. The material used to make the disc depends on the indented application of the tilting check valve.
Seat
This is the part where the disc seats when the valve is closed. The seat material just like the disc depends on the intended application of the valve. The seat can be soft seated or metallic seated. The soft seats are made of plastic or rubber material and tilting disc check valve manufacturers recommend such seats for low-temperature applications. The metallic seats can withstand high temperatures and thus they are used in high-temperature applications.
Gasket
This is the material placed between the valve port and the pipe to enhance a tight seal with zero fluid leakage. Also, the type of material used to make the gasket depends on the expected application of the tilting check valve.
How does a tilting disc check valve work?
A tilting disc check valve operates by employing pressure difference. This makes the valve operate automatically without the use of a valve actuator or valve handwheel/lever. The pressure difference is the principle in which the valve disc opens when the suction pressure is more than the outlet pressure and it is high enough to produce energy sufficient to push the disc open. The fluid pressure is provided by the pump of the piping system. Once the valve is opened by the suction fluid pressure it keeps flowing through the valve until when the suction pressure reduces to be less than the outlet pressure or when there is backflow. At the instance of low suction pressure or backflow, the valve disc reverts to the seating position automatically. Tilting disc check valve manufacturers also use spring to help the disc is returning to the seating position immediately after fluid pressure reduces. Such a valve can be installed in either vertical or horizontal positions.
Figure: Working of a tilting disc check valve.
Types of tilting disc check valve
Split body tilting disc check valve
This is a tilting disc check valve with two pieces of the body. The two pieces are oriented horizontally to each other and collinearly to the pipe. The two pieces of the tilting disc check valve are connected using bolts and nuts. A gasket is placed between the two pieces to ensure there is a tight seal and zero fluid leakage. Split body disc check valve manufacturers recommend this type of valve for use in high-pressure applications. This is because the bolted connection of the two pieces of the body makes the valve very strong enough to withstand high-pressure levels. However, the strong body and the number of bolts and nuts and flanged ends make the valve very heavy relative to other types of tilting disc check valves. One advantage of this tilting disc check valve is that inspection, cleaning, and repair of the valve can be done easily after opening the two pieces of the body.
Figure: Split body tilting disc check valve.
Tilting disc check valve with a pressure seal
This is a tilting disc check valve in which the bonnet and body are connected using a pressure seal. A pressure seal is a method of connecting the bonnet and the body for valves meant for use in high-pressure applications. A tilting check valve with a pressure seal is such that the body-bonnet seal becomes tighter as the fluid pressure increases. Tilting disc check valve manufacturer design these valves for use in applications such as petrochemical, oil, and gas, steam, and boiler circulation among others.
Figure: Tilting disc check valve with a pressure seal.
Wafer tilting disc check valve
This is a tilting disc check valve that uses a disc-like plate to close and open fluid flow. The design employs two half discs or plates which are pivoted on a center post that is a hinge pin. Torsion springs are used to hold the half discs in the seating position against the valve body. A pin parallel to the hinge pin is used to restrain the plates from free turning. Fluid flow force on the plates is transmitted to the valve springs. This makes the springs stretch forward as they allow fluid to flow through the valve. The extent to which the valve plates open depends on the amount of fluid force. The more the fluid force the more the plates will open. To make the valve close faster, tilting disc check valve manufacturers use stronger springs making them more sensitive to slight suction pressure reduction and thus close faster. However, the very high strength of the springs can make it hard for the suction pressure to open the plates. So tilting disc check valve manufacturers aim to balance the suction pressure and the spring strength.
Figure: Wafer tilting disc check valve.
Welded body tilting disc check valve
This is a tilting disc check valve that is made by welding the body and body together. Tilting disc check valve manufacturers design this type of valve for use in areas where the valve is transporting high pressure or hazardous fluids. The valve is taken through non-destructive testing to ensure it is free from any defects which may cause leakage or any malfunction when in use. Welded body tilting disc check valves are very reliable since they are free from fluid leakage despite high fluid pressure. However, these valves cannot be inspected, cleaned, or repaired while in the field. In case the valve develops a problem, the weld has to be removed before inspection or repair.
Applications of tilting disc check valve
- Tilting check valves are used in the treatment and distribution of water.
- They are used in heating, ventilation, and air-conditioning systems.
- They are used in fire-fighting systems.
- Tilting disc check valves are used in oil and gas applications.
- These valves are used in mining industries.
- They are used in drilling and shipbuilding applications.
- Tilting disc check valves are used in the manufacturing of petrochemicals and chemicals.
- They are used in food and beverage processing.
- They are used in the paper and pulp industries.
Advantages of tilting disc check valve
- Tilting check valves operate quickly thus saving time and ensuring no reverse fluid flow which may cause contamination.
- These valves are automatic which reduces the need for a valve actuator.
- Tilting disc check valves have high efficiency because they have a low-pressure drop.
- These valves can maintain working pressure.
- They have no fluid leakage.
- These valves can be used in both low and high-temperature applications.
- Tilting check valves are versatile as they are used in different industries.
- They are durable as they can be repaired for reuse in case they break down.
Disadvantages of tilting disc check valves
- Tilting disc check valves tend to cause water hammer and associated effects.
- They cannot be inspected while in use.
- They are difficult to repair relative to the other check valves.
Troubleshooting tilting disc check valves
Tilting check valve producing noise while in operation
- It is normal for a tilting disc check valve to make minimal noise. However, if the noise becomes loud like a hammering problem it could be due to cavitation due to dropping high pressure. Ensure the fluid velocity is as recommended by the tilting disc check valve manufacturer.
Valve does not close
- Solid particles interfering with valve disc. Open the valve and remove any foreign material inside. Clean the valve interior.
The tilting check valve does not open
- Low differential pressure. Ensure the inlet pressure is more than the outlet pressure.
- The downstream valve is closed. Open the valve downstream.
- The pipe connected to the tilting check valve is blocked. Check the valve for any foreign materials causing blockage and remove them.
Fluid leakage when the valve is closed
- Debris in the valve. Open the tilting disc check valve and clean any debris.
- Worn out seat. Replace the valve seat.
- Worn out or damaged O-rings. Replace the O-rings.
Fluid leakage through flange mating faces
- Loose connection. Tighten the bolts and nuts.
- Worn out gasket. Replace the gasket.
Summary
A tilting disc check valve is a type of check valve that uses a tilting disc to open and close the fluid flow. These valves are meant to prevent reverse fluid flow which occurs due to low suction pressure than the outlet pressure or due to backflow of fluid. Tilting disc check valve manufacturers use springs or may not use springs depending on the design of the valve. A spring is used to help in reverting the disc to the seating position immediately after fluid attempts to reverse flow direction. Tilting disc check valves without spring depend on the backflow of the fluid to close the valve preventing reverse flow. Tilting disc check valve manufacturers design these valves with strong materials to make them suitable for use in both high pressure and high temperatures. The body is made of strong metallic materials such as carbon steel, stainless steel, and ductile iron among others. Tilting disc check valves operate automatically without using a valve handwheel or actuator. They depend on suction fluid pressure to open and close. There are various types of tilting disc check valves which include split body tilting disc check valve, wafer tilting disc check valve, tilting disc check valve with pressure seal, and welded body tilting disc check valve. Applications of these valves include oil and gas, petrochemicals, chemical manufacturing, foods and beverages, water treatment and distribution, and steam power plants among others. Advantages of using tilting check valves are automatic operation, versatility, zero leakage, high efficiency, ability to maintain pressure, fast operation, and no reverse fluid flow.