×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Contact US

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!

*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

Stress in Pipe due to Shear Lug/Plate

Stress in Pipe due to Shear Lug/Plate

Stress in Pipe due to Shear Lug/Plate

(OP)
Alright, I'm working my way through a design and I'm struggling a bit with this last step.  I have a horizontal line that is restrained using a hold down strap (vibration strap) and I am attaching a rolled plate to the top 180° of the line.  It basically looks like half of a full encirclement reinforcement pad.  The plate is to act as a bumper against the clamp as an emergency stop in the event of a line break.  I've designed the strap, bolting, shear plate, and weld for the load due to the pressure thrust of the line.

However, I'm having trouble making the final step of the effect of the weld line itself on the stress in the pipe.  The plate is welded to the line on three sides - the two longitudinal sides, and one of the 180° sides.  The other 180° side is up against the strap.  This configuration was chosen to keep the force on the pipe as close to a pure shear as possible and minimize bending.  Most of the references and techniques I'm familiar with are concerned with the effect of bending due to the moment arm of an attachment like a shoe or dummy leg.  The shear aspect seems to generally be neglected as not contributing greatly to the stress.  However, in this case, the shear is really the only contributor to the stress.

I'm going to take another run through my Roark Stress and Strain to see if I've just missed the application somewhere.  If anyone has any other references, I'd appreciate it.

Edward L. Klein
Pipe Stress Engineer
Houston, Texas

All opinions expressed here are my own and not my company's.

RE: Stress in Pipe due to Shear Lug/Plate

Ed,

Find someone with Nuclear Plant piping design experience and see if they have an old Bechtel or Stone & Webster pipe lug guideline. These companies developed an integrated guideline for evaluation of pipe lugs and the combination of stresses on the pipe wall.

The Piping fabrication Institute (PFI) published a guidleine on lugs and allowable weld shear versus temperature (www.pfi-institute.org) see publication ES-26

Additionally, ASME wrote two code cases some 15 years ago that addresses the problem you are interested with. You should contact a Mr. John Breen (a frequent eng-tips contributor)who is very familiar with these code cases and thier application.....

Hope that this helps


MJC

RE: Stress in Pipe due to Shear Lug/Plate

depending on the size of the piping, would the zick´s method give an approximate result of any value?

RE: Stress in Pipe due to Shear Lug/Plate

abeltio,

Nope,

The LP Zick methodology is used where there is a saddle support on a thin-walled horizontal cylinder. The highest developed stresses are commonly found at the "horns" of the saddle. Since the problem described by "STRESSGUY" is on a piping system, the Zick method is inappropriate....

The 1950's era Zick paper is still in use because it contains empirical curves which were developed at considerable time and expense.

See these links for more info:

www.computereng.com/products/zss.htm
revobiz.dyndns.org/group/seaint/2002a/msg00741.html


Good Luck

MJC

RE: Stress in Pipe due to Shear Lug/Plate

Ed,
Right now I am working on a nuclear project in Taiwan and
we analyzed all rectangular or circular attachments on piping and here are the Nuclear Code Cases(ASME SEC III Div. 1) that we used.

N-122-2 Procedure for Evaluation of the Design of Rectangular Cross Section Attachmnents on Class 1 piping

N-318-5 Procedure for Evaluation of the Design of Rectangular Cross Section Attachmnents on Class 2 & 3 piping

N-391-2 Procedure for Evaluation of the Design of Hollow Circular Cross Section Attachmnents on Class 1 piping

N-392-3 Procedure for Evaluation of the Design of Hollow Circular Cross Section Attachmnents on Class 2 & 3 piping

These code cases are already in a program by GE,so the only thing that we do is just specify the lug sizes and input the
load on the lugs and the program will combine the stress due to lugs.

Regards,
Ellie



RE: Stress in Pipe due to Shear Lug/Plate

(OP)
I'll definitely check those out.  Thanks!

Edward L. Klein
Pipe Stress Engineer
Houston, Texas

All opinions expressed here are my own and not my company's.

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! Already a Member? Login


Resources

Low-Volume Rapid Injection Molding With 3D Printed Molds
Learn methods and guidelines for using stereolithography (SLA) 3D printed molds in the injection molding process to lower costs and lead time. Discover how this hybrid manufacturing process enables on-demand mold fabrication to quickly produce small batches of thermoplastic parts. Download Now
Design for Additive Manufacturing (DfAM)
Examine how the principles of DfAM upend many of the long-standing rules around manufacturability - allowing engineers and designers to place a part’s function at the center of their design considerations. Download Now
Taking Control of Engineering Documents
This ebook covers tips for creating and managing workflows, security best practices and protection of intellectual property, Cloud vs. on-premise software solutions, CAD file management, compliance, and more. Download Now

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:

Register now while it's still free!

Already a member? Close this window and log in.

Join Us             Close