Repair of Turbine Shaft

Probably the problem was originated in poor lubrication of bearings (O poor quality of lubricant used). Also, it may be due to poor alignment due to vibration or fixing elements. Another possibility is that the shaft is deflected by a hot soak. The vibration control (Inspection) during the life of the equipment must be rigorous.

1.- Best option.New coatings such as thermally sprayed ceramics have successfully been used as protective barriers and compensation of eroded surfaces.

See this AWS link:

http://www.aws.org/wj/amwelder/11-00/abc.html

2.- Yes.

3.- You can try with metallic or epoxi shims. Not recommended. Only temporary emergency

WP

Hello,

Will this ceramic coatings withstand the operation speed of 6000rpm?

Consider an SKF Speedi-sleeve, they are available in sizes right up to 200mm diameter and would most likely solve your problem. No resizing of shaft and doesn't affect original seal sizes if there are any involved.

There are numerous other manufacturers of similar product, Google shaft repair sleeve and you should get a few to work with.

Dear Friend,

0.2 MM i.e., 200 MICRONS is too large deviation. Highly risky to attempt to repair and run. Better go for new shaft and simultaneously study the causes why this 200 MICRONS wear out has taken place and it is to be avoided.

DHAYANANDHAN.S

i think the reason of wear of the shaft shows the bearing jam that can be due to lake of lubrication and heat (which causes the bearing ball stuck ).

the better solution is to turn (rough ) the shaft just to make it perfect round and the plasma metal spray coating will be best solution for the wear up-to 0.5mm wear it have good penetration with various metals .

In old days we used to metalize such shafts. I do not know if it is still possible.

I highly recommend not metal spraying or coating the journal area with a spray coating. The one thing that might work is having the journal nittrided. You can build up to 10 mils thickness and then polish the shaft back to the disired diameter. The .2 mm is 7mils loss in diameter. This is the only coating that might stay in place due to it's hardness. You did not say what type of bearing you have in the unit. If they are a ball diameter with a poured babbit then machine the journal and make a bearing to fit. If your unit uses insertabe bearing like a clevite type insert you will have to talk to the manufacture to see if they sell a bearing to fit. The best alternative is to replace the shaft and clean up your oil and then maintain the oil cleanness by monitoring it. You also need to give more info when asking a question of this caliber. It would make it a lot easier to answer correctly.

Dear Sir,

Thank you very much for the advice.

This bearing is split plain bearing.(Manufacturer specifies this as spiral bore) Bearing manufacturer is Waukesha bearings. Turbine manufacturer is no longer available. This turbine was built is 1960s. Oil filtering system is through a steel mesh screener where aperture is not mentioned.

From what I understand. Your bearing is a split type (Sleeve Type) similar to an automobile engine bearing. This can be made undersoze to fix your problem. Also talk to Clevite bearings as they make undersize bearings. I have had new shafts made for small high speed turbines and moved all the wheels and seals to the new shaft with good results. A good machine shop can do this and also you end up with a blueprint for a new shaft in case you ever destroy another one. This way you stay with original design bearings. Hope this helps.

I agree. The wear is 0.007 - 0.008 inches, too think for plating in this application. It would be better to sleeve the shaft or remake the bearing to the undersize dimension.

What I do recommend is to put a thin (0.001-0.002 inch) electroless nickel or similar hard surfacing treatment on the bearing journal to avoid excessive wear in the future.