×
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

4 hinged expansion joints

4 hinged expansion joints

4 hinged expansion joints

(OP)
I have a question for experts in pipeline and expansion joint design.
We have a pipeline like this (carbon steel, 350°C) and our supplier gave us this layout.
I've never seen 4 hinged EJs in this configuration, it has 1 degree of freedom!!!
So what do you think about it?

RE: 4 hinged expansion joints

The arrangement has a infinite number of possible positions that could be adopted. A stress analysis using software would not tell you this and would simply converge on the first deformed shape it finds.

A piping system is normally analysed as a structure. Due to the number of degrees of freedom (and it's not 1 !!), this is a mechanism.

RE: 4 hinged expansion joints

(OP)
It's a four-bar linkage, so it has 1 DOF.

RE: 4 hinged expansion joints

Four hinges have rotational freedom, two have translational freedom in two planes.

It is a mechanism. Piping systems are normally structures.

The arrangement as shown has no control over the position it may adopt. EJ's have specific rotational limits, beyond which, failure can be guaranteed.

Did you want a discussion about semantics or perhaps some useful comments aimed at avoiding a catastrophic failure ?


RE: 4 hinged expansion joints

What size is this line?
What are the two dimensions from each "Anchor" to the Elbow (Change in direction)?

prognosis: Lead or Lag

RE: 4 hinged expansion joints

(OP)
I wanted only your answer "It is a mechanism. Piping systems are normally structures."

Pipeline: DN250
Dimensions: about 3mx10m (I'm not involved in thi work, so I don't know exactly)

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