×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!
  • Students Click Here

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

Jobs

Lubricated & Non-Lubricated Plug Valves?
5

Lubricated & Non-Lubricated Plug Valves?

Lubricated & Non-Lubricated Plug Valves?

(OP)

As far as I know there are Lubricated Plug Valves & Nun-Lubricated Plug Valves.

According to my short experience Non-Lubricated Plug Valves are mainly used in process industries like petrochemical or refining & Lubricated Plug Valves are used in Crude Oil Pipelines.

Can anyone tell my why?

Thanks,

Nerio.

RE: Lubricated & Non-Lubricated Plug Valves?

Nonlubricated plug valves are used in Chemical and process services.  They actually ARE lubricated: The plug rides in a PTFE sleeve or liner.  

Lubricated plug valves are used in applications where the lubricant will not render the process contaminated.  Mining, gas, petroleum are reasonably typical.  To cycle a nonlubricated plug valve, it is appropriate to first exercise the lubricator, forcing sealant between the plug and the body.  This "floats" the plug clear of the body so it can be turned.  Sealant (frequently called "grease" is specially formulated for the intended application, and the sealant selected should not be washed away nor react with the process fluid.

Take a look at the Flowserve.com website under "Durco" for nonlubricated plug valves and for "Nordstrom" for Lubed valves.   

RE: Lubricated & Non-Lubricated Plug Valves?

2
The petroleum refinery I worked at uses lubricated valves, plug or otherwise.  However, they are bad-mouthed because the "don't work."  The irony is that they don't work because nobody lubricates them, properly if at all.

Too much or not enough grease can cause problems and we could never get the operations & maintenance folks to do the right thing, even with training.  Debating union job duties came into play.

RE: Lubricated & Non-Lubricated Plug Valves?

(OP)
It would be too bad if I mount a Non-Lubricated Plug Valve on Crude Oil Service?

Thanks,

RE: Lubricated & Non-Lubricated Plug Valves?

There are those of us that feel that the only reason to use plug valves is if ball valves have not yet been invented (they were a huge improvement over gate valves in the 1960's).  

I spent a lot of time and money ripping them out of a natural gas gathering system I operated because we simply did not have the attention span to keep them properly lubricated.

David

David Simpson, PE
MuleShoe Engineering
www.muleshoe-eng.com
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.

The harder I work, the luckier I seem

RE: Lubricated & Non-Lubricated Plug Valves?

Non lubricated plug valves are used for RO plants. Contamination of the mebranes cannot be tolerated and hence a lubricated plug valve is of no use. Butt welded plug valves up to Class 600 are common in RO plants. MTs from Spain are a key manufacturer.

Geoffrey D Stone FIMechE C.Eng;FIEAust CP Eng
www.waterhammer.bigblog.com.au

RE: Lubricated & Non-Lubricated Plug Valves?

>>It would be too bad if I mount a Non-Lubricated Plug Valve on Crude Oil Service?
<<

Not a problem as long as the crude oil service is within the published ratings of the plug valve.  

zdas04, One big difference between plug valves and ball valves: If the plug valve leaks, it can be adjusted to restore shutoff. This is particularly true of nonlubricated plug valves.   If a ball valve starts to leak, you shut down the line, pull the valve, strip out the guts, and replace the seat(s).  

RE: Lubricated & Non-Lubricated Plug Valves?

I've seen few "properly maintained" plug valves in upstream service.  One that was greased on schedule and exercised quarterly started leaking through.  We tried all the adjustments available and finally pulled it out.  The plug was badly gouged by trash and had a significant leakage path.

In upstream, if a ball valve leaks through and injecting grease doesn't fix it, we replace the whole valve--the downtime to kit it is worth more than the savings.

David

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members!


Resources