Tests for welded rotors

[diegoisonline]

Hello to All,

I am a young mechanical engineer just graduated and I've been hired in an consultant company. Now the job is requires me to prescribe which tests must be perfomed by supplier for a steam turbine rotor which is made by two pieces welded together. The material used is for both the pieces ASTM 470-8. The operating conditions of the turbine are:

ADMISSION
Pin= 100barg T=505°C

EXHAUST
Pout=0.14barg T=52.6°C

Thank you for your advice.
Diego

 

[metengr]

diegoisonline;
The tests I would recommend are based on the vendor that is going to weld the rotor. Is this for new construction or to repair an existing rotor?

Some of the tests to think about are as follows;

Existing rotor;
1. Determine the chemical composition of the rotor.
2. Perform nondestructive examination (ultrasonic examination and wet fluorescent magnetic particle inspection) of the rotor to check for service-related cracking.
3. Have a metallurgical lab perform an evaluation of the rotor steel microstructure to evaluate in-service damage.
4. Welding will need to be performed using an ASME or other equipment standard welding procedure specification along with qualified welders. The qualificsation of the WPS will require hardness testing and microstructure evaluation, as well.
5. Nondestructive testing will need to be specified after all welding is completed.
6. Have a welding engineer and met lab at your disposal to review the entire welding program and condition assessment results.

New Rotor
Go directly to steps 4-6 above. If an OEM has been selected to build then rotor, you and an experienced turbine engineer that has a welding/materials background needs to visit the shop and review from top to bottom, material selection, design, welding processes, NDT, etc.

What I don't understand is why they put you into this position. There is a company that can help you evaluate various vendors and their proposals and even offer to QA/QC this job. The company is Liburdi Engineering in Canada.

 

[arunmrao]

Metengr,

In my experience it is often the myopic management that overrides several issues regarding procedure qualification etc.

In order to save some money they incur huge risks. Very rarely does the Technical department or end user raise their objections for fear of losing jobs.

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