Project Lead - Steam Turbine

1.1 MATERIAL INSPECTION

Third party inspector shall examine the original or authenticated copies of mill certificates of material for compliance with specifications, and where appropriate with drawings. The review includes checks on:

• Certificate No;
• Heat or Cast No;
• Chemical Composition;
• Mechanical Properties;
• Heat Treated Condition;
• NDE Applied and Results;
• Surface Finish.

1.2 FABRICATION INSPECTION

The third party inspector checks the following items in the steam turbine fabrication inspection process:

• Visual inspection for damage;
• Dimensional check to drawing requirement;
• Inspection of parts, for cleanliness;
• Visual examination of welded on connections;
• Review of welder qualifications;
• Review of weld procedure record;
• Confirmation of satisfactory NDE;
• Proper documentation of the materials used;
• Examination/inspection of integral parts such as reduction gears.

1.3 INSPECTION TESTS

1. Hydrostatic Tests

The Steam Turbine and other pressure containing parts are hydrostatically tested. The main items are:

• Turbine casing;
• Steam chest;
• Emergency stop valves;
• Governor valves.

2. Rotor Balance Test

3. Over Speed Test

4. Clearance Checks

The following areas are examined:

• Radial clearance between rotor and casing;
• Axial clearance between the rotor blades and stationary points.

5. Mechanical Running Test

Following items are taken into account for gas turbine mechanical running test:

• Steam condition (temperature, flow rate);
• Lubricating oil condition (viscosity, temperature, flow);
• Cooling water condition (temperature pressure, flow);
• Critical speed;
• Bearing temperatures;
• Vibration (Synchronous speed, Blade passing etc);
• Operation of Sentinel valve;
• Operation of trip and throttle valve;
• Hand trip operation;
• Governor oil condition (temperature/pressure);
• Noise level.

6. Governor Test

The following characteristics are important:

• Operation of over-speed trip emergency system by a consecutive 3 time test;
• Fluctuation of the Governor at rated speed;
• Governor rang.

7. Performance Test

Third party inspector witnesses the gas turbine performance test and following points are taken

in account:

• Satisfactory completion of previous tests;
• Power Output;
• Thermal Efficiency.

8. Mechanical testing:

• Tensile testing;
• Charpy Impact Testing;
• Drop Weight Test;
• Hardness Testing;
• Hydrogen Embrittlement;
• Stress Rupture;
• Creep Test;
• Weld Testing;
• Heat Treat Capability Testing.

9. Fracture and fatigue testing:

• Fracture Toughness Testing;
• Fatigue Crack Growth Testing;
• High-cycle Fatigue and Low-cycle Fatigue Testing.

1.4 FINAL VISUAL INSPECTION

A visual examination including a partial strip down of the unit is usually required by the specification and is witnessed by third party inspector. The particular areas of interest are:

• Journal bearing pods;
• Thrust bearing pods;
• Rotor shaft with thrust collar;
• Shaft seal rings;
• Rotor blades;
• Tooth contract in gear trains.

1.5 PAINTING AND COATING INSPECTION

It is necessary that surface condition is free from pinholes, runs damage and other discontinuity. Surface preparation for painting checked for the following points, according to specification:

• Soluble salt contamination test;
• Solve Cleaning;
• Blast Cleaning type (white metal blast cleaning or near-white metal blast cleaning);
• Surface Preparation degree;
• Freedom from weld spatter, blow-holes and other defects, dust free surface before primer application;
• Dry film thickness measurement according to specification.