×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Are you an
Engineering professional?
Join Eng-Tips Forums!
• Talk With Other Members
• Be Notified Of Responses
• Keyword Search
Favorite Forums
• Automated Signatures
• Best Of All, It's Free!

*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.

# pump motor alignment3

 Forum Search FAQs Links MVPs

## pump motor alignment

(OP)
I believe that on high energy Boiler Feed Pumps, it is customary to align (cold) the BFP 4-6 mils low, relative to the motor, in anticipation that the running centers will be coincident when the pump and motor are on-line.  My maint. supervisor stated that the Plant's current practice is to align the motor low, claiming that the centerline of the motor will rise as the motor gets hot, but the pump centerline remains fixed.  Who's right?

### RE: pump motor alignment

The most logical approach would seem to be to assume more thermal growth of the pump than motor, similar to your logic. Since often motor is more easily-moved than pump (piping constraints), it would make sense to initially set the motor high.

Of course any calculations you do using thermal coefficient of expansion and estimated temperature difference can be way off.  Best approach is to take actual measurements of alignment changes between hot and cold using Ludeca's permalign or similar equipment.

### RE: pump motor alignment

ChipBurton,

The conclusion to your question is dependent on many factors:

1) What is feedwater temperature?  It is not unusual to have temperatures anywhere from a little over 100 DegF to 200 to 300 DegF or higher?

2) What is pump design? Radial split or horizontal split casing?

3) Is pump centerline or base mounted?

4) You may want to check with your maintenance personnel as to how they decided to set the difference in elevation?  Maybe they have some good rationale for this setting.

5) I generally don't like rules of thumb for such settings, since there are so may possible variations.

### RE: pump motor alignment

Motor thermal growth should be available from the motor manufacturer
We pump cold water with some 600 kW motors and have to align the motor low, but if you are pumping hot water then the pump will grow too.

Worlds Best practice is an educated guess at first then re-align when the unit is hot.  A bit of a hassle at first but t hen the knowledge is there forever!!!!

#### 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.

#### 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

Research Report - How Engineers are Using Remote Access
Remote access enables engineers to work from anywhere provided they have an internet connection. We surveyed our audience of engineers, designers and product managers to learn how they use remote access within their organizations. We wanted to know which industries have adopted remote access, which software they are using, and what features matter most. Download Now
eBook - Managing the Context of Product Complexity Using the Digital Twin
Keeping track of changes to complex products is difficultâ€”think Aerospace & Defense equipment, new generations of commercial aircraft, and software-based automobiles. A new way to managing the digital context of the physical product is required and the answer is the Digital Twin. This ebook explores the opportunity available for Operations and Maintenance for the Digital Twin. Download Now
White Paper - Trends in Industrial Filtration
Substantial progress has been made in filtration technologies in recent years. New filter media materials, designs and processes have led to filters that are more efficient, reliable, compact and longer lasting. This white paper will discuss the various trends that are impacting operational responsibilities of MROs today and the resources that are available for staying up-to-date on the latest filtration solutions. 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:

• Talk To Other Members
• Notification Of Responses To Questions
• Favorite Forums One Click Access
• Keyword Search Of All Posts, And More...

Register now while it's still free!