×
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

Interpretation of BTH-1-2017 re: Lifting Magnets

Interpretation of BTH-1-2017 re: Lifting Magnets

Interpretation of BTH-1-2017 re: Lifting Magnets

(OP)
This will be cross-posted in Structural Engineering Other Topics.

In BTH-1-2017, Section 3-1.2, there is this language about lifting magnets:

"The loads used in the design of the structural and mechanical components of a lifting magnet shall be derived based on the maximum breakaway force of the magnet. Resolution of these loads into member and connection forces shall be performed by an accepted structural analysis method."

Later, in 6-2.1, (b):

"Lifting magnet suspension devices should meet the lifting magnet manufacturer's recommendations. If any such devices are used during breakaway testing and are not rated for the breakaway force of the lifting magnet, they shall be removable for the purpose of load testing as required by ASME B30.20."

My question is, in the first passage, what is their scope of the term "lifting magnet"? Are they referring to the magnet itself, or is it used to identify the entire lifting device, such as a lifting beam which carries 4 magnets? In the second passage they seem to differentiate the magnet from what suspends it (like a lifting beam?). The implication, or the reason I ask, is that as it relates to the design of the beam, it would have to be designed for the breakaway force of the magnets, as opposed to being designed for the stated rated capacity.

Thanks in advance for any responses.

RE: Interpretation of BTH-1-2017 re: Lifting Magnets

My interpretations are: First components of the magnets such as each magnetic coil holding device(that secure the coils to the magnet frame) should be design on the maximum break away force. To me that may seem excessive design when you may have several holding devices but don't there could be uneven loading on the magnet as I remember that lifting loads should be spread evenly. Secondly, the lifting beam design should be based on the total maximum break away force of the four magnets as it appears that there may be a significant reduction between the maximum break away force and the manufacturer's rated load; but as prudent as I may be, I would double check on that reduction factor with the manufacturer since I would also include the weight of the magnets and all fittings, wire rope, etc... needed between the beam itself and the magnets. I would also design an extra factor into the beams for shock loading and excessive beam deflection. "...the purpose of load testing as required by ASME B30.20." that requirement may be consistent with OSHA 1910 regulation on load testing of shop fabricated beam so double check.

RE: Interpretation of BTH-1-2017 re: Lifting Magnets

(OP)
Thanks for the response, much appreciated.

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


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