×
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

Question about ASME section I

Question about ASME section I

Question about ASME section I

(OP)
.Boilers

Could someone help and give the formula wall thickness for an ellipsoidal head ( 2:1).

I was expecting something like
t =( P*L) / [ 2*S -0.2*P])

with  L = 0.9*D   
D= Boiler diameter corroded

.......I started doubting when I saw THE FORMULA

T = (5*P*L) /( 4*8*S)
 

RE: Question about ASME section I

You are mixing up things.
The first formula is for a thick full hemispherical head, the second one for a dished head.
For a 2:1 ellipsoidal head the code requires the minimum thickness being the same as for a cylindrical shell with the same diameter.
You should have the code in your hands if you need to do this type of calculation or check other's calcs: for each calculation there are side rules and limits to be fulfilled.

prex
http://www.xcalcs.com : Online tools for structural design
http://www.megamag.it : Magnetic brakes for fun rides
http://www.levitans.com : Air bearing pads

RE: Question about ASME section I

(OP)
prex
thanks for this clarification.

---------------
I have the Code..the point is how to read it !!

For 2:1 ellip heads= are you refering to paragraph PG-29.6 ?
if not please specifiy which paragraph is applicable to ellip. heads



What is the exact definition of a dished head then??
is and 2:1 ellip. head not a dished head ??

RE: Question about ASME section I

The paragraph is PG-29.7.
A dished head, otherwise called a torispherical head, has a central spherical portion with large radius (usually equal to shell diameter), and a torical knuckle with a small radius that connects to the shell. A 2:1 ellipsoidal has an elliptical shape (theoretically) in a diametral section and the depth is half the shell radius.

prex
http://www.xcalcs.com : Online tools for structural design
http://www.megamag.it : Magnetic brakes for fun rides
http://www.levitans.com : Air bearing pads

RE: Question about ASME section I

An ellipsoidal head can be approximated by a dished section (crown radius) that is 90% of the OD and a knuckle that is 17% of the OD.  In no case can the dish radius exceed the OD of the skirt (shell) nor can the dish radius be less than 6%.

The formula in PG-29.1 is the correct one for dished heads unless they are hemispherical.  Note that the divisor is 4.8 not 4*8.

EJL

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