燃气涡轮工程手册 Gas Turbine Engineering Handbook 3(78)

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They should be sent to special training sessions where hands-on experience can be gained.
After the completion of basic machinist training， the machinist shouldcontinue his training with on-the-job experiences. His skills should betested， and he should be encouraged to take on different tasks.
To develop the skills of in-house personnel， as much repair work as pos-sible should utilize plant personnel. Encouraging the participation of the machinist in the solution of difficult problems often results in the machinist seeking information on his own. References to API and ASME specifications should not be uncommon on the shop floor. Today"s machinist and mechanic must be computer literate. Internet training must be provided with some basic training on word processing and spreadsheet programs.
c. 8asic Machinist Training. Most of the basic training can be devel-oped and conducted by in-plant personnel. This training can be highly detailed and tailored precisely to meet individual plant requirements. Train-ing must be carefully planned and administered to fit the requirements of different machinery in the plant.
Many plants have a full-time training program， and personnel for con-ducting training at this basic level. Good maintenance practices should be inculcated into the young machinist from the beginning. He should be taughtthat all clearances should be carefullychecked， and noted both before and after reassembly. He should learn the proper care in the handling of instru-mentation， and the care in placing and removing seals and bearings. A basecourse on the major turbomachinery principles is amust， so there is basic understanding of what these machines do and how they function. The young machinist should also be exposed to basic machinery-related courses such as:
1. Reverse indicator alignment

2. Gas and steam turbine overhaul

3. Compressor overhaul

4. Mechanical seal maintenance

5. Bearing maintenance

6. Lubrication system maintenance

.. Single plane balancing
Tools and Shop .quipment
A mechanic must be supplied with the proper tools to facilitate his jobs. Many special tools arerequired for different machines， so as to ensure proper disassembly and reassembly. Torque wrenches should be an integralpart of his tools， as well as of his vocabulary.
The concepts of ""finger tight"" and ""hand tight"" can no longer be appliedto high-speed， high-pressure machinery. A recent major explosion at anoxygenplant， which resulted in adeath， was traced back to gas leakage due to improper torquing. A good dial indicator and special jigs for taking reverse indicator dial readings is a must. The jigs must be specially made for the various compressor and turbine trains. Special gear and wheel pullers are usually necessary.
Equipment for heating wheels in the field for assembly and disassembly are needed; specially designed gas rings are often used for this purpose.
A maintenance shop should have the traditional horizontal and verticallathes，mills， drill presses， slotters，bores， grinders， and a good balancing machine. A balancing machine can pay for itself in a very short time in providing a fast turnaround and accurate dynamic balance. Techniques to check the balance of gear-type couplings for the large high-speed compres-sorsand turbine drives， as a unit should be developed. This leads to the solving of many vibration related problems. High-speed couplings should be routinely check-balanced.
By dynamically balancing most parts， seal life and bearing life is greatlyimproved， even on smaller equipment. Dynamic balancing is needed on pumpimpellers， as the practice of static balance is woefully inadequate. Verticalpumps must be dynamically balanced; thelong， slender shafts are highly susceptible to any unbalanced-induced vibration.
This assembly and disassembly of rotors must be in a clean area. Horses or equivalents should be available to hold the rotor. The rotor should rest on thebearing journals， which must be protected bysoft packing， or theequivalent， to avoid any marring of the journals. To accomplish uniformshrinkfits， the area should have provisions for heating and.or cooling. A special rotor-testing fixture should be provided; this is very useful inchecking for wheel wobbles， wheel roundness， and shaft trueness. Rotors in long-term storage should be stored in a vertical position in temperature-controlled warehouses.
　
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