×
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

Roof Frangibility

Roof Frangibility

Roof Frangibility

(OP)
Tank Information
Diameter = 60m
Internal Design Pressure = 1.62kPa
Roof = Supported Cone
Roof Slope = 9º

The client is requesting that the tank roof be frangible. The tank meets the frangibility requirements per 5.10.2.6, with maybe the exception of the compression ring type.
The Appendix F.5.1 calculation results in a large compression area required and it is difficult to get the required compression area using Fig F-2 details a-e.
1)  Is it the intention of figure F-2 that standard structural angles be used?  
2)  Can a large fabricated angle (eg. 300 x 300 x 25) be used to meet the frangibility requirements and gain the area required, keeping within the wc and Le limits?  

Thanks

RE: Roof Frangibility

I would assume that it is the intent that standard structural angles be used.  Are you checking the area requirement in 5.10.2.6-5 as well?

Frangibility implies a low failure pressure, and pressurized construction per Appendix F imvolves raising the design and failure pressure, so you will reach a point where the tank simply can't be considered frangible per API rules due to the pressure design.

RE: Roof Frangibility

JStephen,
Your last sentence is a good point.  It might be true that for certain configuration of tank sizes that frangibility might be limited by the amount of compression resistance area provided on the roof joint offered by the standard structural angle shapes.

I always thought that the idea of a frangible joint is applicable to the entire pressure range (0- 2.5 psi) permitted by this standard as long as the required top ring stiffness is met.  Hence, I would think that we should be able to "leap" to detail h or detail k to provide the needed area.  

 

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