According to the different maintenance scope, the maintenance of steam turbines can generally be divided into three levels: minor repair, medium repair and major repair.
1. Minor repairs
1) Inspect and repair bearings with high vibration or shaft displacement during operation.
2) Inspect and repair the bearings with higher temperature in operation and the corresponding upper and return lines.
3) Eliminate all kinds of pipelines, valves, flanges running, running, dripping, leaking.
4) Eliminate other faults and defects that occur during operation.
2. Medium repair
1) Includes all the contents of minor repairs.
2) Dismantle and inspect radial bearings and thrust bearings, measure the amount of wattage, the back of the tile, the oil seal clearance, the rotor channeling amount and the channeling amount, and adjust or replace the parts if necessary.
3) Check the integrity of the shaft journal and thrust plate, and trim if necessary.
4) Each coupling and coupling bolt cleaning, measuring the simple floating amount of coupling sleeve, checking the internal and external tooth sleeve coordination, wear, and non-destructive flaw detection of coupling bolts.
5) Check the cleaning cylinder body slip pin, check and adjust the main pipe brackets, spring hangers.
6) Clean and check the critical breaker, measure the gap between the lever and the shaft displacement boss of the critical interrupter and the head of the critical interrupter.
7) Check and clean the control valve transmission mechanism; test the operation of the main gas valve.
8) Adjust the system to do static debugging, steam turbine to do overspeed test (during the annual overhaul).
9) The main condensate pump and the main lubricating oil pump are defused and repaired.
10) The review of the unit maintenance is correct, and the update is correct after the maintenance.
3. Overhaul
1) Includes all the contents of the middle repair.
2) The steam turbine opens the cylinder block, dismantles all the parts for cleaning and inspection.
3) Rotor cleaning and descaling, macroscopic inspection, shape and position status inspection, non-destructive flaw detection of relevant parts, and residual magnetic inspection and electromagnetic deviation inspection of the rotor if necessary.
4) The fastening of the root and tension of several stages of long blades after the inspection of the condensing steam turbine, the static frequency of each individual blade or group of blades should be determined for blades with a length of more than 80mm.
5) According to the operation situation and actual inspection situation before the rotor maintenance, decide whether the rotor will undergo a dynamic balance test or replace the spare rotor.
6) Clean and inspect the cylinder, partition, static leaf holding ring, static blade at all levels, nozzle, etc., and do coloring inspection.
7) Clean all levels of air seals, balance plate seals, shaft end air seals, etc., measure the gap between air seals in various parts, and repair or replace damaged parts.
8) The cylinder, partition and bearing housing center are inspected and adjusted according to the situation.
9) Check the working position of the rotor in the cylinder block, measure the clearance of each flow part, and adjust it according to the situation.
10) Disintegration inspection control valve, wrong throttle oil motor, starter, pressure converter, etc., measure the clearance of relevant parts, valve head, valve seat flaw detection inspection.
11) Dismantle and inspect the main air valve, critical security device and other safety protection devices.
12) The governor is tuned and set.
13) Check and clean the governor gearbox, measure the bearing clearance, the meshing clearance of the reduction gear and the worm and worm gear clearance.
14) Car reel inspection.
15) Auxiliary condensate pump, auxiliary lubricating oil pump to solve physical repair.