×
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

Relief valve by-pass??

Relief valve by-pass??

Relief valve by-pass??

(OP)
Hello,

I would like to know fi you have ever seen by-pass lines on relief valves?
Could you please tell me their purpose? and how to size them?

Thank you in advance

"We don't believe things because they are true, things are true because we believe them."
"Small people talk about others, average people talk about things, smart people talk about ideas and legends never talk."
 

RE: Relief valve by-pass??

You would probably have to narrow down your question to get a sensible answer, as a 'relief valve' cover a fairly vast area of valves and applications. The reason for the bypass would also have to be defined:

I can think of at least one example:

If you start with a pressure reduction station in a water supplying net, you would ideally have pressure reduction valve with filter in front, isolating valves upstream and downstream, and a bypass string of all, with a manual throtteling valve, to secure water supply downstream at downtime of the reduction valve.

The pressure reduction valve station would ideally have the same layout if you replace the pressure reduction valve with an overpressure control valve, keeping the upstream pressure constant within a certain limit.

In this case the bypass would have to be designed to give sufficient outlet (defined by max inlet) to avoid overpressure.

In all cases I can think of (you have also some similar systems within hydro-elecrical stations regulating outlet by turbine downtime) the bypass is a 'doubling up' of automatic or driven valves, with a simpler, cheaper 'extra' line for safety reasons, mostly with manual regulation.

Dimensioning: sufficient to give flow of necessary amount for the downtime periode.

One special application: If you have a safety relief valve with a bursting disc upstream, you could also have a smaller manual 'bypass' connected to the pipeline between the disc and PSV, just to check the pressure here to ensure the bursting disc is not leaking.

?????
 

RE: Relief valve by-pass??

I've installed them as a way to get the vessel blowdown into the flare header, why tap the flare header twice.

RE: Relief valve by-pass??

(OP)
I am talking about safety relief valves placed on top of equipment and discharging either in a flare of at atmosphere

"We don't believe things because they are true, things are true because we believe them."
"Small people talk about others, average people talk about things, smart people talk about ideas and legends never talk."
 

RE: Relief valve by-pass??

Per my understanding, we shouldn't called it as "by-pass lines on relief valves". Infact it is just a simple manual blowdown.

* Bypass for some device or equipment mean your process continue to work with the device or equipment. In reality you shall NOT bypass relief valve !!!

JoeWong
Chemical & Process Technology

RE: Relief valve by-pass??

(OP)
I agree thanks

"We don't believe things because they are true, things are true because we believe them."
"Small people talk about others, average people talk about things, smart people talk about ideas and legends never talk."
 

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