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Flange Butterfly Valve Installation & Maintenance Manual - Part Two

- Jan 26, 2018 -

²  The Main Parts Material



Part Name




Steel backing F4






Ductile Iron,   Stainless Steel, Carbon Steel


Body Seal Seat

Stainless Steel, Cu   Alloy


Disc Sealing Ring

NBR, EPDM, Stainless   Steel


Stuffing Ring

Ductile Iron, Carbon   Steel, Stainless Steel,



Ductile Iron, Carbon   Steel, Stainless Steel,


Taper pin

Stainless Steel



NBR, EPDM, Flexible   Graphite


²  Characteristic Curve

      Head Loss Curve                                                               Flow Curve





Flow Characteristic Curve

 flow CV.png

Note: The flow characteristic curve shows the relationship between the open degree of the valve and the flow rate. 

In general, the butterfly valve is suitable for flow control, but when the valve opening angle is below 20 , it is not recommended to control the flow rate.


²  Installation And Maintenance

- The valve can be installed at any angle on the pipeline.

- The arrow on the body is the main pressure direction and the reverse pressure is 50% -60% of the main pressure.

- Valve installation position should be guaranteed to use, and easy maintenance.

- The valve should be installed before the completion of the following tasks:

1)      Check carefully to ensure that the use of the valve in line with its performance specifications.

2)      Must be the valve body, valve plate seal with the clean parts, or not allowed to open the valve.

3)      The valve should be stored in a dry place in the room before installation and the valve plate should be opened 4-5 °


- When the valve is installed in the pipeline, the flange bolts on both ends must penetrate from the outside of the flange and be evenly fastened.

- After the valve is installed, the pipe must be in the open position for strength testing.

- After the valve is installed and used, it needs regularly to check the valve effect.


²  Malfunction and Elimination Methods

Possible   Failure

Reason   For The Failure

Troubleshooting   method

Sealing   Surface Leakage

Seat   ring is scratched;

Seat   has the debris;

The   pressure ring fastener is not tightened

Replace,   repair sealing seat;

Clean   the body cavity;

Tighten   the fasteners

Shaft   Leakage

The   nut on the shaft packing gland is not tightened;

The   gland of the shaft is not pressed;

Filler   failure;

Tighten   the nut;

Tighten   the gland fasteners;

Change   the packing

Leakage   of the flange ends between the valve and the pipeline

The   connection bolts is loose, bolts tightening is uneven, rubber gasket is aging

Tighten   the connecting bolts evenly;

Replace   the rubber pad