A Comprehensive Guide for Operating and Maintaining Butterfly Valves

A butterfly valve is a flowing regulated device which includes a rotational disk to operate the flowing liquid in a process. On a perpendicular location of the butterfly valve, there is a metal-based disc which operates the closing technique of the fluid flowing. The operation of closing off of this valve is quite same as that of a ball valve. The advantages of using it over a floating ball valve are:

• It is light weight; hence it don’t require much support
• It is less costly as compared to other similar valves with different designs.

Parts Of A Butterfly Valve

A rotatable actuator helps to operate the disc sideways or sometimes in a perpendicular position to the flow. Whereas in the ball valve, the disc is located within the flow which generates a pressure fall, even when it is open. One of the best options is the XHVAL butterfly valve which works excellent in many types of industries.

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A butterfly valve consists of 4 main parts- the body, the valve, seat, and a disk.

1. Body

The body is in between 2 pipe edges. There can generally be two designs based on which butterfly valves are made up of – Lug and Wafer.

Lug butterfly valves, as the name suggests, contains extended lugs which can join the valves. These valves are again attached to the edges of the pipes at the end. This helps easy replacing and removing the process of the pipe length.

A Wafer body doesn’t contain any extendable lugs. The wafer body is placed centrally between the pipe edges, and the bolt surrounds the whole body.

2. Seat

The seat of the strong seated butterfly valve works as an interference between the disk rim and the seat. The material of the seats can be of polymers or varied elastomers. The seat can either be joined or pressed or locked inside the body.

For high performance, the shut off can work as an interference -fit seat design or a line seat design. This is to increase the pressure in the pipeline and at the border of the disc. Because of different compatibility and temperature variations, the seat material used is mainly polytetrafluoroethylene (PTFE). Metal-based seats are also great for high performance of the butterfly valves.

3. Disk

A disk is designed to stop the fluid flow. There are variations in the designs of the disks depending on the operation and improvement of the flow.

4. Valve

The valve is designed to get safe protection from the media. It also allows a well-organized selection of materials. The valve can be either one-piece design or two (spilled) designs.

Operation of Butterfly Valve

 The disc of the butterfly is centrally positioned, and a rod infiltrates through the disc. The disc is again attached to a regulator known as an actuator, situated at the outer surface of the valve. To begin with the operational feature, we have to understand the pre-installation and installation of the butterfly valve to get a clear picture of it.

Installation Of Butterfly Valve

There are a few installation key points and a checklist to follow:

1. Be assured about the working conditions, i.e., temperature and pressure within the designated capacity of the product getting installed.
2. The construction material of the valve should be compatible with the chemicals of the media/fluid flowing through the pipeline.
3. The valve ends, pipelines should be clean and defect-free. This should be investigated well.
4. The sufficient clearance for installing the value is an important thing. For that, check the distance between the pipeline edges.
5. To lift the larger valves, the material of the butterfly valve should be complete and appropriate.
6. The pipe sizes should match with the inlet and outlet size measurements and dimensions of the unit which is getting installed. Important note: If you notice any strain in the pipelines (which happens due to the weight) then add extra support to it.
7. A six diameter from the upper end and about four diameters from the lower end of a butterfly valve is advised for safe installation.

How to Install Butterfly Valve

1. For manually operated valves, you need to install a lever and use a hand-wheel technique for a geared system valve.
2. After fitting the lever/hand wheel accordingly, you have to rotate the valve clockwise to make sure it is airtight. The alignment of the disc should be done parallel to the ends.
3. If you find the disc alignments are not parallel then follow the steps-

For Lever Mechanism

•   Release the top plate slightly.
•   Open the two bolts loose.
•   Then you can rotate the lever clockwise.
•   Check the alignment of the disc parallel to the ends.
•   Fit it.
•   Then you can tighten the top plate again.

For Geared Valve 

•   Simply adjust and bolt the nuts situated on the gearbox.
•   Open it completely.
•   Then close the disc again and do it a couple of times.
•   Until the alignment is done perfectly parallel to the end, repeat the process.

4. Install the valve into the pipe. For wafer style butterfly valve, place it directly at the center in-between the flanges at the two ends of the pipe. Secure it with bolts to pass through the fluid. For Lug Butterfly valve install at the center of the flanges just like the wafer style but secure the screws at both inlet and outlet sides of the valves.
5. Remove the foreign particles if found obstructing the pipe flanges.
6. Please ensure that the technique is properly done and then tighten the bolts placed on the flanges.
7. You can apply pressure the pipe towards the valve to check if there is any leakage or no. If leakage persists, then you have to again clean and tighten the bolts by using the criss-cross method. Make sure that the bolts are lubrication-free and dirt free.

Maintenance of Butterfly Valves

To take precaution against rusting and grease the butterfly valves should be maintained well.

1. At the top of the valve, there is grease fitting. This may not be observed at the arrival of the valve. Make sure to apply grease at an interval to the neck of the valve till the excess grease flows out.
2. At the gearbox, you can apply lithium based grease for its maintenance.
3. You can clean all the parts of the valve easily by using any silicon-based product/lubricant.
4. Try rotating or cycling the butter valve once a month if it’s not used regularly.

Conclusion

A butterfly valve is a reliable, tight fit, the bi-directional valve which is used in various industries like food, ship, etc. Fitting a butterfly valve is absolutely a cost-effective way as compared to other valves. Butterfly valves also serve the purpose of directing the flow and shutting off the liquid/gas brilliantly by closing the valve disc.