×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Are you an
Engineering professional?
Join Eng-Tips Forums!
• Talk With Other Members
• Be Notified Of Responses
• Keyword Search
Favorite Forums
• Automated Signatures
• 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.

# The stress on F&D head is extremely high in ANSYS Workbench as compared to ASME VIII Div-1.

## The stress on F&D head is extremely high in ANSYS Workbench as compared to ASME VIII Div-1.

(OP)
Issue: The stress on F&D head is extremely high in ANSYS Workbench as compared to ASME VIII Div-1 calculation.
Vessel OD: 96”, 106” Seam-Seam
Thickness: 0.4375”
Pressure: 105 psi
Material: SA-24 316L.
The baseplate of Leg as fixed.

I did ANSYS analysis for F&D (ASME 80:10) head. The obtained Eq. stress was 35,000 psi (Membrane stress: 25k) which is extremely high as compared to code calculation. Code calculation gives 14,000 psi.

I performed a similar comparison with the 2:1 Ellipsoidal head. The ANSYS Eq. Stress was 18,000 psi (Membrane Stress: 12,000 psi). This is close to code calculation, code calculation gives 11,500 psi stress.

Also, there was high stress (30k psi) in SUPPORT LEG for the F&D head and just 9k in the ellipsoidal head.
The setup and procedure of analysis were the same for F&D and Ellipsoidal head but there was a high deviation from the code calculation in the case of F&D head while analysis of Ellipsoidal head is in line with code calculation. What can be the cause of deviation in the F&D head?

PS: I have ignored stress concentrated at a point due to singularity.

Replies continue below

### RE: The stress on F&D head is extremely high in ANSYS Workbench as compared to ASME VIII Div-1.

When you say "code calculation", exactly which calculation are you meaning?

### RE: The stress on F&D head is extremely high in ANSYS Workbench as compared to ASME VIII Div-1.

(OP)
By code Calculation, I mean ASME Section VIII, Div-1.

### RE: The stress on F&D head is extremely high in ANSYS Workbench as compared to ASME VIII Div-1.

I mean, what EXACT calculation/formula are you using. There are multiple calculations in UG-32, Code Case 2260, Appendix 1-4(d), and 1-4(f). Each gives a slightly different result.

May I suggest you take a look at this paper for some additional formulae.

### RE: The stress on F&D head is extremely high in ANSYS Workbench as compared to ASME VIII Div-1.

I would recommend getting a copy of "ESDU 67017 - Elastic Stresses in the Torispherical Head of a Pressure Vessel of Uniform Thickness"
It has tables and graphs of the principal stresses in the knuckle and crown on the inside and outside surface for all sorts of t/D, KR/D, CR/D. From standard ASME Tori's to 2:1 Ellipses.

### RE: The stress on F&D head is extremely high in ANSYS Workbench as compared to ASME VIII Div-1.

You say the membrane stress was 25k but your figure shows 17k? Also, looks like there's some bending in the legs in the first figure; is gravity applied? Are there other loads applied?

#### 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.

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:

• Talk To Other Members
• Notification Of Responses To Questions
• Favorite Forums One Click Access
• Keyword Search Of All Posts, And More...

Register now while it's still free!