Inspection of Steam Turbine Components

3angles meets all NDT requirements for the inspection of steam turbines for different OEM’s. Our NDT services for steam turbines typically include the inspection of the following components:

  • Turbine Rotors
  • Stationary Blading
  • Casings and Shells
  • Bearings
  • Bolting
  • Valve components
  • High Energy Piping

The inspections of these turbine components are performed during a major or minor outage. During a major outage, all or most of the turbine components will be inspected while during a minor outage the turbine is partially disassembled, and the inspection focuses only on the parts that are accessible or disassembled. Some outages just focus on the valve components and many times inspection of repairs made are part of the scope of work as well.

Probably the most critical part of the steam turbine is the turbine rotor. 3angles performs magnetic particle inspection on the rotor periphery using one of its proprietary 10,000 AMP mag machines. A headshot is performed providing a circular magnetic field to find indications in the axial direction. The coil or bucking field technique is used for creating a longitudinal field finding indications in the radial direction.

Based on design and OEM, steam turbine inspections may require other unique or specialized inspections based on rotor design and configuration. Examples of these inspections are:

Boresonics inspection: Boresonics inspection examines the forging of a rotor through the bore cavity. The inspection can be performed for straight, step, and bottle bore configurations. Removal and installation of the bore plug(s) and power honing of the bore surface are part of the process.

Periphery ultrasonic testing (UT): Ultrasonic testing examines the forging of a rotor from the periphery of the rotor for indications.

Wheelsonics dovetail testing: This examination looks for indications caused by stress corrosion cracking (SCC) in the wheel-blade attachment area to prevent bucket liberation.

Disk bore and keyway examination:  This examination looks for indications caused by stress corrosion cracking in the disk wheel bore area for shrunk on disk style rotors.

Trepan inspection: This examination is applicable for some Westinghouse turbine configurations. The scope of work includes the inspection of the nozzle chamber pipes (Trepans). The inspection will be performed per the guidelines presented in the Westinghouse OMM 13 and OMM 14 service bulletins. A wet black powder magnetic particle inspection will be performed in the Trepan areas utilizing a borescope. An ultrasonic inspection will be performed on the bell seal welds.

Hardness testing: Hardness testing employs a test to check the hardness of a material which can be used as part of the evaluation.

Replica Testing: Replica testing determines creep damage and is used in the remaining service lifetime assessment of a component.