Keeping blades in good health is a fast way to recover efficiency and minimize unplanned outages. This guide outlines a simple process with some helpful insights that you can create, develop, or incorporate into your existing internal shop process. Work in an organized manner, add documentation as needed, and prioritize safety and traceability!

What Tools Do You Need?

Staging your work area and knowing that all of the gauges are in calibration is important before you begin. Consider an equipment kit specifically for the blades to eliminate searching for consumables when you are busy in your work. Two minutes spent now could save countless hours later.

• PPE: cut resistant gloves, face shield, hearing protection, respirator
• Precision measuring tools: micrometers, calipers, dial indicator, surface roughness gauge
• NDT Equipment: dye/fluorescent penetrant kits, UV light / developer to confirm fluorescent penetrant inspection
• Cleaning Equipment: solvent station, ultrasonic cleaner, and blast cabinet with approved media
• Cutting and blending Equipment: variable-speed rotary tools, carbide burrs, flap wheels, etc.
• Welding Equipment: GTAW/TIG machine, a preheat oven or torches, and thermocouples/temperature crayons
• Fixturing: blade stands, root clamps, and angle blocks to help maintain twist and chord during the work
• Records: repair travelers, heat charts, and photo log system for traceability.

Follow this page https://www.cdc.gov/niosh/learning/safetyculturehc/module-5/2.html for occupational safety standards.

Cleaning and Surface Preparation Explained

Start with a good degrease to remove oils, oxides and deposits, then proceed with a controlled media blast (per your procedure) into the base metal, without radius-edging or confounding profiles. This stage often determines the success of turbine component repair.

You will then do NDT to demonstrate cracks, porosity, and fretting on the root, platform and leading/ trailing edges. After the NDT, mark reject areas, mask the zones to be protected, record measurements for dimensional inspection. And you do not proceed to repairs until the surfaces are clean, dry, and determined to be good.

Welding and Repair Basics

Your intent should be to Restore lost material and shape while controlling heat – using appropriate filler material which is close in composition to the base alloy, following the WPS, and recording the preheat/interpass temperature. The variation of heat affected zone should be kept small.

• Verifying compatibility of parent material and filler; retrieving the most current WPS/PQR; stamping the traveler
• Preheating according to the procedure; monitoring the interpass temperature; develop a uniform heat pattern to protect HAZ
• Use of GTAW/TIG, using short beads, packed light weave and frequently cleaning interpass to limit dilution
• Building up in layers, over filling slightly, and able to machine back to profile
• If required stress relieve or control cool down for stability of repair
• Recording amperage, voltage, travel speed, and passes for traceability of repair

Finishing Techniques for Blade Life Extension

Once welding is completed, you have to restore the profile, machining or grinding to the chord, camber, and twist tolerances in your drawing specs, and blending transitions for airflow attachment. If you have their specification for surface finish requirements, you’ll have to match and apply shot peening as required to put the beneficial compression stress back in.

If your drawings have coatings (erosion resistant, anti-fouling, corrosion protection) you’ll need to prepare the surface to cleanliness grade, apply coating while within the required temperature/humidity window and cure according to the data sheet. Clean the root and platform that will contact, to ensure the proper seating of the blade with no high spots.

Quality Checks Before Reinstallation

The final verification avoids scope creep that may turn into rework in the pit or vibration call after roll-up. When inspecting the blade, it’s key to inspect it as a singular part, but also inspect it checking it as an assembly with the other blades from the row, so that the fit, weight, and geometry cooperate with the row, and everything goes back/preps for build. If you’re off – fix it here; it’s only more challenging to address when the blades are assembled.

• Repeat dimensional inspection of chord, thickness, twist and squareness of the platform, and compare dimensions with limits from the drawing
• Repeat penetrant NDT (Non-Destructive Testing) at heat affected areas to ensure that no new indications are present
• Weight pieces and complete high-precision balancing or weight matching by bucket set, per the row plan
• Blue-check the root/dovetail for contact and remedy any high spots to limit fretting and stress-risers that could lead to component failure
• Verify surface finish and peen coverage (if specified) and complete coating thickness and adhesion verification
• Complete all documentation: measurements, weld maps, heat charts, pictures and signoffs, and prepare for QA release

Final Thoughts

The refurbishment of steam turbine blades is a step discipline: Clean, Inspection, Repair, Finish, Verification. When you execute these steps—and document each step—you will maximize the life cycle of the component, protect the efficiency of the system, and keep your unit online longer while reducing surprises.