Inspectioneering
Inspectioneering Journal

Bolt Behavior: Part 3

By Del Underwood at Det Norske Veritas. This article appears in the May/June 2011 issue of Inspectioneering Journal.
3 Likes
Related
  • Bolts
    A Bolt is a threaded fastener that has an external male thread used in conjunction with nuts to attach separate pieces of equipment together. Bolts are often used to hold together sections of pipelines,...
  • Mechanical Integrity (MI)
    Mechanical Integrity (MI) can be defined as the management of critical process equipment to ensure it is designed and installed correctly, and that it operates and is maintained properly (i.e. no leaks and all elements are fit for service). A mechanical integrity program should...
  • Process Equipment
    Much of the equipment used in the refining and processing industries is known as Process Equipment. Most pieces of process equipment are designed to perform specific, singular tasks. Process equipment can be used for tasks as varied as storage, controlling flow, and...
  • Bolt Behavior: Part 2
    March/April 2011 Inspectioneering Journal
    In the previous issue we dealt with the fact that bolts can withstand significantly less cyclic loading than steady loading. We are now looking at the mechanics of why bolts fail if flanges are allowed to separate during operation.
  • Bolt Behavior: Part 1
    January/February 2011 Inspectioneering Journal
    A continually frustrating phenomenon to many of us is the situation where a tight bolt will function satisfactorily, but in the same situation, a loose bolt will fail...
This article is part 3 of a 3-part series.
Part 1 | Part 2 | Part 3

 

In two previous issues we discussed the important difference between steady and cyclic loading, and why loose bolts fail while tight ones do not. This issue will offer two suggestions for reducing the tendency for bolts to become loose.

The first deals with the rigidity of a bolt and its stress concentration factor. Figure 1 shows two typical flange stud bolts, each being of equal strength for steady loading, but the one with reduced mid section being stronger for cyclic loading.

Figure 1
Figure 1

The effective load bearing cross section for a bolt is the root diameter of the threaded area. The second bolt has the same effective cross section as the first, even though the center portion has been machined down to the root diameter. So, for steady loading, the two bolts are essentially the same.

This content is available to registered users and subscribers

Register today to unlock this article for free.

Create your free account and get access to:

  • Unlock one premium article of your choosing per month
  • Exclusive online content, videos, and downloads
  • Insightful and actionable webinars
GET STARTED
Interested in unlimited access? VIEW OUR SUBSCRIPTION OPTIONS

Current subscribers and registered users can log in now.

About the Authors

Del Underwood at Det Norske Veritas

Comments and Discussion

There are no comments yet.

Add a Comment

Please log in or register to participate in comments and discussions.

 Sign up for our weekly newsletter.
Join the Inspectioneering LinkedIn group Follow Inspectioneering on Twitter Follow Inspectioneering on Facebook
Copyright © 2024 Inspectioneering, LLC. All rights reserved.
Inspectioneering Journal

Inspectioneering Journal

Explore over 20 years of articles written by our team of subject matter experts.
Company Directory

Company Directory

Find relevant products, services, and technologies.
Training Solutions

Training Solutions

Improve your skills in key mechanical integrity subjects.
Case Studies

Case Studies

Learn from the experience of others in the industry.
Integripedia

Integripedia

Inspectioneering's index of mechanical integrity topics – built by you.
Industry News

Industry News

Stay up-to-date with the latest inspection and asset integrity management news.
Blog

Blog

Read short articles and insights authored by industry experts.
Interviews

Expert Interviews

Inspectioneering's archive of interviews with industry subject matter experts.
Event Calendar

Event Calendar

Find upcoming conferences, training sessions, online events, and more.
Downloads

Downloads

Downloadable eBooks, Asset Intelligence Reports, checklists, white papers, and more.
Videos

Videos & Webinars

Watch educational and informative videos directly related to your profession.
Industry Acronyms

Acronyms

Commonly used asset integrity management and inspection acronyms.