×
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

Bolted Flange in Bending

Bolted Flange in Bending

Bolted Flange in Bending

(OP)
Anyone know where I can find a good hand calc for a bolted circular flange connection in pure bending?

I need a calc that will give me the axial force on each bolt.

RE: Bolted Flange in Bending

Koves' paper in JPVT from Feb 1996 includes a summary of the available methods (at the time) of dealing with external bending moments.  Personally, I prefer to use EN-1591-1 (or EN-13445-3 Annex G).

I will ask a question in return - why do you need this information?

RE: Bolted Flange in Bending

(OP)
I need to back up an FEA.

RE: Bolted Flange in Bending

How are you treating your gasket?  What type of gasket do you have?

RE: Bolted Flange in Bending

(OP)
There is no gasket - it is a structural flange.

RE: Bolted Flange in Bending

If that's the case, then a simple free-body-diagram and a little bit of static equilibrium with a healthy dose of compatibility should answer your question.

RE: Bolted Flange in Bending

(OP)
I'll admit I haven't gone that far into the calc because there seems to be too many unknowns.

Imagine a round flange under bending with 12 bolts - the bolt at top dead center takes a large percentage but the others take smaller percentages decreasing to the neutral axis of the joint.

I believe these percentages are based on the general geometry..but I am not sure.

I just wanted to see if there was any literature whereby someone has already done the legwork.



RE: Bolted Flange in Bending

There's too many unknowns for the static equilibrium equations.  That's why you also need the compatibility equations - assume that your flange is rigid (or not, in which case this will be an iterative process) and figure that the flange is rotating, pivoting around the one edge.  Then, the load in each bolt will be based on the "stretch" caused by the rotation.

Unfortunately, you are going to have to get up to your elbows in the calc - no easy way around it.  And, you might learn something more in the process :-O as opposed to having someone hadn you the calc.

RE: Bolted Flange in Bending

(OP)
Ok, thanks alot for your input.

RE: Bolted Flange in Bending

Look in Maleev's "Machine Design" p. 125 for a rigid bracket flange.

for pipe flange w/ extermal loads & moments:
Kellogg's  Piping Design book, also:

Walther J. Stikvoort's articles:
"Proper Interface Design for Pressure Vessels" in Chemical Engineering June '94 p133-4.

"Piping Reaactions on Pressure Vessel Nozzles" in Chemical Engineering, July 7, '86 pp51-3.

"Pressure Vessel Design, Nozzle Piping Reactions" in Encyclopedia of Chemical Processing & Design,Vol.42, [NY:Marcel Dekker] 1993, pp 237-44.

Also: C.J. Dekker, "External Loads on Nozzles," Int.Jnl Pres. Ves. & Piping, 53(1993) p.335-350.



RE: Bolted Flange in Bending

Assume that each bolt will stretch linear to its distance from the edge of the flange. Then assume the force in the closest bolt is X. Every other bolt will have a force greater or equal to X depends on its ration of its distance from edge compared to the distance of the closest bolt. Sum the products of each force and its distance from the edge and equal it to the bending moment. This will give you the force X and the force at every bolt. Now tight each bolt to a preloaded force greater than the maximum force in the bolts.

RE: Bolted Flange in Bending

Assuming flange is resonablr stiff, the max bolt load is 4M/(ND)
M=moment
N= number of bolts
D=pitch circle diameter

Steve Braune
Tank Industry Consultants
www.tankindustry.com

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