×
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!

*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

Low Pressure Storage Tank PSV Discharge Destination

Low Pressure Storage Tank PSV Discharge Destination

Low Pressure Storage Tank PSV Discharge Destination

(OP)
Hi Folks,
I'm designing a tank farm to be located in Texas. There are three low pressure, blanketed tanks connected to a flare stack. The emergency venting requirements (fire case) would lead to a very large flare header. My question is can I design the tanks with a weak roof-to-shell joint, or a weighted thief hatch, so that they relieve to atmosphere in the event of a fire? or do I need to connect them to the flare header? API 2000 seems to imply the former. NFPA 30 and OSHA 1910.106 seem to imply the latter. These three tanks would sit in the same dike as several other atmospheric tanks holding stable (high flash point) hydrocarbons. In the event of a pool fire, those tanks will relieve to atmosphere though open vents and weighted thief hatches.

Apologies if this has been answered elsewhere.

Thanks

Scall

RE: Low Pressure Storage Tank PSV Discharge Destination

There are no requirements to route low pressure tank vents (normal load or emergency load) to a flare header. As illustrated by your preliminary sizing calculations, it's almost impossible (and certainly impractical) to attempt to route a fire relief loads (from low pressure tanks) to a flare header.

For emergency loads such as fire exposure, you can choose to protect the tank using a frangible roof seam or by using an emergency vent valve routed to the atm.

RE: Low Pressure Storage Tank PSV Discharge Destination

(OP)
Thanks Don,
Appreciate the help.
Scall

RE: Low Pressure Storage Tank PSV Discharge Destination

Recall that Frangible Roof Design (FRD) is meant to prevent shell uplift during over pressurization which may cause failure of the bottom to shell joint. Rupture of the shell to roof joint is judged always preferable to rupture of the shell to bottom joint

FRD is also meant to prevent damage to piping, sumps and appurtenances resulting in a release of a tank’s contents.

Be aware that there are design limitations to storage tank frangible roofs !!!!
Your preferred selection of roof type and anchorage design must also be evaluated


http://citeseerx.ist.psu.edu/viewdoc/download?doi=...

For the roofs of smaller diameter tanks they are not permitted by API-650 (Section 5.10.2.6)

Frangible roof designs have been discussed repeatedly over the years on "eng-tips"

https://www.eng-tips.com/viewthread.cfm?qid=338992
https://www.eng-tips.com/viewthread.cfm?qid=394841
https://www.eng-tips.com/viewthread.cfm?qid=373545

Be aware ....

There has been, over the years, some challenges to the basic concepts and fundamental methodologies of "frangible roof design" for API-650 Tanks

http://docshare02.docshare.tips/files/4813/4813518...

MJCronin
Sr. Process Engineer

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! Already a Member? Login


Resources

Taking Control of Engineering Documents
This ebook covers tips for creating and managing workflows, security best practices and protection of intellectual property, Cloud vs. on-premise software solutions, CAD file management, compliance, and more. Download Now
The Great Project Profitability Debate
A/E firms have a great opportunity to lead the world into the future, but the industry’s greatest asset—real-time data—is sitting wasted in clunky, archaic ERP platforms. Learn how real-time, fully interactive dashboards in a modern ERP allow you to unlock data that will shape the future of the world. Download Now

Close Box

Join Eng-Tips® Today!

Join your peers on the Internet's largest technical engineering professional community.
It's easy to join and it's free.

Here's Why Members Love Eng-Tips Forums:

Register now while it's still free!

Already a member? Close this window and log in.

Join Us             Close