12" butterfly sticky issue 3

[Rakesh2560]

We have 12" butterfly valve which has sticking issues this butterfly valves are triple eccentric with pneumatic actuators and are used in cyclic regeneration service when at the end of each cycle the butterfly valve is closed it often sticks we are looking forward to investigate the issue the service does have carbon as the steam is used for washing a carbon bed would appreciate the suggestion from fellow engineers as I am still new to learning about valves

 

[btrueblood]

What kind of seals? Can you fit a larger (higher breakaway torque) actuator?

 

[btrueblood]

Oh, and materials of construction for the valve seat, and piping? Condensate drain system for the steam piping? Any corrosion inhibitors used? And why pneumatic actuators? Finally, you say it sticks at the end of cycle when the valve closes - do you mean it sticks open? Or is it "stuck" and not opening at the next cycle?

 

[btrueblood]

Oh, and why were these types of valves chosen?

 

[Rakesh2560]

Thanks for your reply btrueblood .The valves were choosen since long time back I am not sure what was the intent behind choosing this valves I think they were choosen for isolation purpose of the steam line as they have to get the acid gas started after closing the steam line which are upstream and downstream of the drum the inlet steam valve is an AOV but is not having any problems for the material I would let you know the exact details in my next post.

 

[gerhardl]

What do you mean by sticky?

Either the valve has to be tested for exact correct closing position, limit and torque switches adjusted to give a 100% correct closing position. Most often this is the issue. Other causes could be that the opening force is higher than expected and/or higher than new. In case of multiturn actuator, check if an extra gear (1-2?)can be added. The extra closing/opening time are most often not critical.

If the valve is sticky because of incompatibel sealing / fluid or because of fluid that gives sticky residues in the pipeline the case is somewhat other. Then you have to look at precleaning or oter type of sealing and/or valve.