Butterfly valves Fault diagnosis - WordPress.com · 17|Butterfly valves | Fault diagnosis Findings...

© InterApp AG | www.interapp.net

Butterfly valvesFault diagnosisInterApp AGApril 2017 / H. Bayrhuber / O. Notz

© InterApp AG | www.interapp.netButterfly valves | Fault diagnosis2 |

Index

• Valve control

• Piping installation mistakes

• Valve installation mistakes

• Operating failures


Operating failures

Water hammer

Findings Valve not operating

Explanation /Avoidance

Deformation or breaking of shaft and disc

Water hammer can be avoided by closing thevalves slowly by means of gear boxes(instead handlevers) and air flow regulators onpneumatic actuators

Non-synchronized pump start and valveoperation as well as trapped air in the pipingcan create water hammer. Use air relief andpressure relief valves or bursting discs

TroubleshootingReplace the valve

Install suitable devices

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Valve installation mistakes

Valve disc jammed, additional rubber gasket in use



Never use additional rubber gaskets

Additional rubber gasket increases the volumeof rubber around the disc

Torque increases!

Troubleshooting

Dismount valve from pipe

Remove gaskets

Replace damaged parts





Valve disc jammed, additional rubber gasket in use


Findings Shaft end twisted or broken


Never use additional rubber gaskets

Additional rubber gasket increases the volumeof rubber around the disc

Torque increases!

Troubleshooting


Remove gaskets

Replace damaged parts




Valve disc jammed, liner displaced from body groove




Ensure enough space during inserting valvebetween flanges.

Troubleshooting


Replace damaged liner

Install valve ensuring enough space betweenflanges.




Valve disc jammed, liner displaced from body groove


Findings Shaft end twisted or broken


Ensure enough space during inserting valvebetween flanges.

Troubleshooting


Replace damaged liner

Install valve ensuring enough space betweenflanges



Piping installation mistakes

Valve disc jammed due to too small inside diameter of flanges




Consider Installation & Maintenance Manualof valve

Consider disc hits the piping flange, especiallywhen installing in plastic piping

TroubleshootingCheck valve disc edges, replace if damaged

Reinstall valve using chamfered stub flanges




Valve disc jammed due to offset mounting between flanges





Consider dics hits the piping flange

Ensure proper centering of valve betweenpipe flanges

TroubleshootingCheck valve disc edges, replace if damaged

Reinstall valve properly centered




Missaligned piping or flanges not parallel


Findings Valve leaking on pipe flange


Missaligned piping creates unevencompression of liner on flange surface

Ensure proper allignement of pipe and flange.

Troubleshooting

Dismount valve, check liner and replace ifdamaged

Refit the piping




Sealing surface of counter flange


Findings Valve leaking on pipe flange


Not smooth surface creates unevencompression of liner on flange surface

Troubleshooting

Dismount valve, check liner and replace ifdamaged

Refit the piping




Use of flanges with too big inside diameter


Findings Valve leaking in flow direction


To achieve maximum pressure rate of thevalve a correct compression of liner ismandatory

Consider Installation & Maintenance Manualof valve.

Troubleshooting Use flanges with correct inside diameter




Insufficient compression of liner downstream


Findings Valve leaking in end of line use


To achieve maximum pressure rate of thevalve a correct compression of linerdownstream is mandatory


Troubleshooting Use correct counterflange downstream orreduce pressure to next lower pressure class




Flange bolts too long or too high tightening torque


Findings Broken body on LUG type


Too long bolts splits the lugs of the body

Too high bolt tightening torque damages thethreads

Troubleshooting

Replace the valve

Use correct screw length

Refere to tightening torque table of screwprovider




Use of U-section body as flanged body type


Findings Broken flange on U-section body


When used as flanged body type, U-sectionbody requires flat face flanges

Tightening raised faced flanges bend or breakthe flange of valve body

Refer to Installation & Maintenance Manual ofvalve

TroubleshootingReplace the valve

Install valve with passing through bolts or useflat faced flanges



Valve control

Too low air supply pressure and flow


Findings Valve is slamming when opening


Power to operate the actuator insufficient

Actuator selection has to consider theavailable air supply pressure

Orifice of air supply system to small

Use air flow regulators on exhaust ports ofsolenoid valve

Troubleshooting

Increase air supply pressure and/or orifice ofall air supply system

Install air flow regulators



Valve control

Working conditions not considered


Findings Valve is slamming when opening


Temperature influences hardness of rubberliners, torque might increase

Consider severe conditions for actuatorselection

TroubleshootingUse correct actuator

Increase air supply pressure on pneum.actuators



Valve control

Chemical attack on liner


Findings Valve is slamming or not opening


Incorrect selection of rubber material leads toswelling of liners

Refer to ValveFinder, material resistancecharts or ask technical support

Troubleshooting Replace liner or valve considering the workingand fluid condition



Valve control

Too high working temperature


Findings Valve is slamming or not opening


Rubber liners are hardening and torqueincreases

Use liners within specified temperature range

Select liner to effective working temperature

Troubleshooting Replace liner or valve considering the workingand temperature condition



Valve control

Power and air supply?


Findings Valve is not operating


Air supply at the actuator missing or air supplypressure too low

Sizing of solenoid valve and / or air supplypiping too small for size of actuator

Power supply missing or wrong voltage

Troubleshooting

Ensure that air supply pressure is according tospecification

Use a bigger solenoid valve and / or air supplypiping according to Installation Manual

Use the correct voltage



Valve control

Solenoid valve in manual mode



Findings Valve is not operating


Manual override of solenoid valve in thewrong position (manual mode activated)

Troubleshooting Put the manual override on automatic (manualmode deactivated)

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Butterfly valves Fault diagnosis - WordPress.com · 17|Butterfly valves | Fault diagnosis Findings...

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