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1st Stage Nozzle Ring

Here's a shot of the first stage nozzle ring installation. Once the compressor and CDC casing was landed, it allocated work for the front and aft end of the unit. As you can see, the manifolds are being worked in parallel with the turbine section.
Lessons learned: when installating new first stage nozzle there is the chance that the previous blocks are not of the right size to set it concentrically. We ended up machining .050" shims using the water jet cutter at our shop. Most utilities are not as fortunate to have such equipment at their fingertips. In that case, purchase larger horizontal nozzle blocks which can be easily machined down to the proper size.

Aftermarket upgrades to aft end compressor

During this outage we upgraded our stage 17 stator and exit guide vanes. The OEM's stator 17 vanes and exit guide vanes is the single airfoil design which are susceptible to vibratory failures. During operating in conditions such as low ambient and part load, flow separation can occur at the S17 bladed due to the inner barrel counter bore cavity and "vortex bursts." This occurs at the S17 tip and causes airfoil distress. The current software modification provided by the OEM redefined the safe operating window that the unit can operate without incurring damage to the unit's S17 and EGV hardware. We've decided to upgrade to a shrouded S17design and shrouded exit guide vanes. The benefits are a more robust S17 and EGV setup which reduces the risks of compressor damage and possibly forced outages. In addition, the modification would eliminate all S17 software protection which defines the limits the safe operating window of the unit. The modification which we chose, shrouded 5 vanes into segments on the 17th stage and exit guide vanes. The modification also retained the existing inner barrel/bore plugs which only required machining a groove to fit the shroud tips. See photos of this modification.

Non-destructive cleaning alternative

The co2 blasting cleaning process is relatively new dating back to the late 1980's. It is quickly becoming favored to such traditional cleaning methods as steam cleaning, sandblasting or solvents. It can be used in a vast assortment of applications especially getting your turbine disk clean for FPI and eddy current inspections. Dry ice pellets are pushed through an air gun and once making contact with the cleaning surface it dissolves and releases C02 gas. Since the pellets are much softer than the base metal surface, there is no risk of equipment damage.
Co2 blasting benefits can be broken down into six general areas. They are as follows:
#1 - Decreased Downtime
#2 - Faster and More Thorough Cleaning
#3 - Elimination of Equipment Damage
#4 - Reduction or Elimination of Solvents
#5 - Reductions in Waste Disposal
#6 - Increased Safety