Categories: Shaft Alignment

Shaft Alignment Thermal Growth Targets–When You Don’t Know

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By on September 23, 2012

In shaft alignment, machines that run hot often have thermal growth targets. Thermal targeting simply means that the shafts may be misaligned while at room temperature, but as they heat up to operating temperature, they will “grow” into alignment.

But where does the thermal growth target come from?

Many times, the machine manufacturer will specify the hot alignment target. It may be listed on the installation drawings, on a machine nameplate or in an installation and maintenance manual. And while these may be fairly accurate, they often are calculated without knowing certain things such as the real ambient temperature, the amount of air circulating around the machine, additional heat sources near the machine, etc.

VibrAlign has created a new app, available for Apple or Android phones and devices, called Therm Align. Therm Align is an interactive app to calculate thermal growth targets of the movable and stationary machines based on averaging temperature measurements from the base of the machine to the shaft centerline. These measurements are taken with a contact thermometer or infrared temperature gun and entered into the Therm Align app. Once the distance dimensions and temperature measurements are input, the app will calculate the thermal growth targets to be entered into your laser alignment system.

Thermal growth in alignment can be a real problem but with the Therm Align app, the calculations just became much easier.

Download Therm Align and other helpful shaft alignment apps from VibrAlign at the Apple App Store and Google Play.

About the Author

Stan Riddle joined VibrAlign in 2008. He has over 35 years experience in aligning industrial machinery. Stan received his AAS Degree in Machinist Technology from Surry Community College in Dobson, NC, and also holds a diploma in Industrial Systems Technology from Forsyth Technical Community College in Winston-Salem, NC, where he was also an instructor in the program.

Stan began his maintenance career working as a machinist and millwright for companies such as Weyerhaeuser, R.J. Reynolds, and Tyco Electronics. He also has over 25 years experience in Predictive Technologies, such as vibration analysis, thermography, oil analysis, and ultrasonic inspection. He is a certified Level III Vibration Analyst with the Vibration Institute, and is a Past Chairman and Board Member of the Piedmont Chapter.

Stan and his wife live in Yadkinville, NC.

5 responses to “Shaft Alignment Thermal Growth Targets–When You Don’t Know”

  1. Ramesh Kumar.R says:

    I am in need of Thermal power plant Fans alignment procedures.

  2. Stan Riddle says:

    There are several sources on our web site to learn more about thermal growth. I counted six blog posts. But I would recommend if you have specific questions regarding a specific machine, that you consult with the fan manufacturer.

  3. Nju says:

    How can we calculate the target dial gauge readings, when we have the combination of vertical and horizontal thermal growth.
    Eg: pump vertical growth 0.08mm
    Pump horizontal growth : 0.21 mm(towards right side)
    NB: rotation view from pump

  4. Stan Riddle says:

    Nju, it depends on the type of measurements. Are you using dial indicators or lasers? If you are using dials, are you measuring using rim and face, or reverse dials? Please feel free to email me directly at I will try to help.

  5. Khemraj kaushik says:

    I have need cement industry ID fan allingment procedure