×
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

High unbalance rotor but very low machine vibration! Why ?

High unbalance rotor but very low machine vibration! Why ?

High unbalance rotor but very low machine vibration! Why ?

(OP)
Dear All,
The talk is about GE HDGT (Heavy Duty Gas Turbine) double shaft driving Centrifugal Compressors.
Right now a MI (Major Inspection) is ongoing on this machine. Because this machine is running over 90.000 fired hours and following OEM Instructions, the HP rotor has been sent to the local OEM Shop for deep inspection and repair if necessary.
It’s the second MI on this machine and it has been running very smooth from its installation 15 years ago. SMOOTH I mean the vibration level is very low about 4mm/s, the alarm setting is 12 mm/s (1/2 inch/s) and the Trip setting is one inch/s.

When the HP rotor installed (as received from the plant)on the balancing machine the readings were very high and the rotor needs to be dismantled and each disc of the rotor will be balanced separately

The balancing readings are (Rotor unbalance as received):
* With Turbine buckets:
...................Plane 1:1526 inch.g / 39.3 deg and Plane 2:1300 inch-g /65.5 deg

* Without Turbine buckets:
...................Plane 1:1582 inch.g / 43.4 deg and Plane 2:1088.7 inch-g /52.5 deg

The run Out of the rotor is acceptable.

Note: The balancing machine double checked and recalibrated but the reading still same same.

My questions:
With same level of rotor unbalance, the machine should vibrate but it’s not the case. How to explain this situation?
What could be the root causes of this rotor unbalance?

Thanks InAdvance and Best regards
Karim

RE: High unbalance rotor but very low machine vibration! Why ?

When was the last time the vibration monitoring system was calibrated ? We have had the same issues with centrifugal gas compressors and often wondered why the vibration levels were so low, and the Bentley Nevada monitoring system was never re calibrated after we took over the plant from the manufacturers.

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

eBook - Manufacturing the Cars of Tomorrow
In this ebook, we'll explore how additive manufacturing is going to transform the way cars are made. This includes commentary from thought leaders such as Ford's CTO, Ken Washington, Customer case studies of ways 3D printing is being used today, and a variety of part examples where 3D printing is already impacting how automobiles are made. Download Now
White Paper - Smart Manufacturing for Semiconductor
New technologies and approaches present great opportunities for semiconductor manufacturers to achieve high levels of innovation, yield and improvement. This white paper explores some of these cutting-edge technologies and how they can be applied effectively in the semiconductor industry. Read about how Smart Manufacturing is transforming the semiconductor industry. Download Now
White Paper - Analysis and Simulation in Aircraft Structure Certification
Organizations using simulation and analysis tools effectively see the benefits in their ability to achieve certification faster and with drastically less total cost than those who do not maximize these tools. Read this White Paper to learn about how digital tools such as analysis and simulation help in aircraft structure certification. 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