×
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

White Paper - The Criticality of the E/E Architecture
Modern vehicles are highly sophisticated systems incorporating electrical, electronic, software and mechanical components. Mechanical systems are giving way to advanced software and electronic devices, driving automakers to innovate and differentiate their vehicles via the electric and electronic (E/E) architecture. As the pace of change accelerates, automotive companies need to evolve their development processes to deliver and maximize the value of these architectures. Download Now
White Paper - Model Based Engineering for Wire Harness Manufacturing
Modern cars, trucks, and other vehicles feature an ever-increasing number of sophisticated electrical and electronic features, placing a larger burden on the wiring harness that enables these new features. As complexity rises, current harness manufacturing methods are struggling to keep pace due to manual data exchanges and the inability to capture tribal knowledge. A model-based wire harness manufacturing engineering flow automates data exchange and captures tribal knowledge through design rules to help harness manufacturers improve harness quality and boost efficiency. Download Now
White Paper - Modeling and Optimizing Wire Harness Costs for Variation Complexity
This paper will focus on the quantification of the complexity related costs in harness variations in order to model them, allowing automated algorithms to optimize for these costs. A number of real world examples will be provided as well. Since no two businesses are alike, it is the aim of this paper to provide the foundational knowledge and methodology so the reader can assess their own business to model how variation complexity costs affect their business. 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