×
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

API-650 Frangible roof

API-650 Frangible roof

API-650 Frangible roof

(OP)
Hi everybody,

When I am determining the frangible roof area (A), I use the formula in 5.10.2.6.
Checking the roof to top angle compression ring. It is limited to details a-e in fig. F-2. Based on these details, I can determine the participating area for the shell (As) and the participating area for the roof (Ar).
Having these values I can subtract A-As-Ar and the result will be the area for the angle (Aa).

My question arises when the result for the Ar is negative. What does it mean?
I wouldn´t need angle for this kind of configuration?
For this case the participating area for the shell plus the participating area for the roof is exceeding the limit value for frangible joint?

Thanks,

RE: API-650 Frangible roof

Whenever the total area exceeds the maximum area for frangibility, your joint is not frangible. If the area of just the roof and shell exceed the limit for frangibility, you can stop there. This does not mean you don't need a top angle, just that you won't have a frangible joint up there. The need for an angle or other structural member up there is from other sections of the code.

RE: API-650 Frangible roof

(OP)
IFRs thanks for your answer.

Anyway I correct a mistake in my post:
My question arises when the result for the Aa is negative. What does it mean?


RE: API-650 Frangible roof

Encho,

Start with the definition of Aa which is the maximum allowable cross sectional area of the angle. If that value is negative, it is not possible to have a frangible roof for the tank and emergency venting must be provided by other means is required by the customer.

RE: API-650 Frangible roof

Note that if a tank is anchored, the requirements are somewhat different.

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