×
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

When Pressure Vessels Blow

When Pressure Vessels Blow

When Pressure Vessels Blow

(OP)
Greetings All,

  I have a question about actual cases where pressure vessels have catastrophically  failed (Deaerators, paper mill digesters, etc).  With cracks present in the vessel, final sudden failure could occur via two means.  One is by a fast cleavage fracture where K1c or J1c are reached at the edge of pre-existing cracks. The other possible mechanism is ductile tensile overload of the remaining unbroken ligament. When actual failures have been studied, did the cracks initially propagate by fast fracture/cleavage or by tensile overload (leaving micro-dimples characteristic of overload on the fracture surfaces)?

Bob    

RE: When Pressure Vessels Blow

bob330;
It is impossible to answer your question because the cause of pressure vessel failure can be from several damage mechanisms separately or working synergistically; cleavage (low toughness), ductile rupture (over stress condition), creep rupture, mechanical fatigue failure, creep-fatigue, etc.

I would suggest you Google pressure vessel failures. On occasion, there are detailed public reports issued by various organizations that promote public safety.

RE: When Pressure Vessels Blow

(OP)
Thanks MetEngr,

  I am only talking about the nature of the  final catastrophic failure of the remaining ligament (which happens instantaneously)  and not what may have caused the pre-crack (typically SCC say for paper mill digesters or corrosion fatigue for deaerators). Thus, the only options are cleavage (fast fracture) or ductile overload.  

bob

RE: When Pressure Vessels Blow

bob330;
Ok, having understood your OP, I would say that for your cited examples of service, the final fracture would be from ductile overload.

The reason is that the operating temperature of the vessel would favor the upper shelf region of the notch toughness curve (assuming no in-service thermal embrittlement or very low toughness steel from steel making practices).

RE: When Pressure Vessels Blow

National Board Bulletins have excellent analysis of catastrophic events and failures.  For example I have copies of features titled "Creep and Creep Failures", "Short Term, High Temp Failures","Microstructural Degradations" and a few others.  Since I have been out of the loop for about 15 years, I don't these analysis anymore.  I would suggest that you contact this organization as I am quite certain they have a feature that may answer your inquiry.

RE: When Pressure Vessels Blow

bob,

One of the more experienced engineering consultants who have dealt with many cases of PV failure is:

THIELSCH ENGINEERING, INC.
195 Frances Avenue, Cranston, RI 02910
Telephone: (401)467-6454 Fax: (401)467-2398

http://www.thielsch.com

There is an extensive list of publications on this website that you may or may not be able to access...

Helmut Theilsch literally "wrote the book" on pressure vessel inspection, repair and failure analysis.

-MJC

  

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