Frame 7EA 12 Segmented New Design Robustness Enhancements capabilities

Turbo Blading News

Stork's capabilites for delivering the upgraded Frame 7EA Compressor Design.

For several years now Stork has been able to supply the latest design evolution for the frame 7EA Compressor, namely the "Compressor Robustness Enhancements" upgrade as implemented by General Electric and described in TIL1884 / GEA32211. The Robustness Enhancements were implemented to increase the longevity of your turbine compressor, and to improve upon the original tried and tested design.

The original six segmented design experienced two issues over the past few years in a small number of units in North America:

  • Clashing / Root Cracking
  • Chordal Tip Liberation

Clashing / Root cracking

Clashing and root cracking can be explained by a frequency problem that occurs during startup and shutdown due to rotating stall. The first Stage Stator Vanes flex modulus (1F) triggers a frequency response caused by ring segment lockup, due to corrosion and oxidation between the ring segments and vanes. To counter this issue, GE altered the design to entail a 12 segmented design, made of a stainless steel to prevent corrosion from causing a lockup.

Chordal Tip Liberation

Tip liberation is caused by crack initiation from a fourth flex (4F) High-Cycle Fatigue (HCF) response amplified by a combination of corrosion pitting and/or loss of damping associated with vane lockup. The stiffness of the vane increased when it is locked into place, resulting in a stress response since the energy is transferred from the dovetail into the airfoil itself due to the corrosion lockup. This response only occurs at or near full-speed operation. This issue is only recorded in corrosive coastal industrial areas such as Middle East and Africa.

Conclusion

Both potential issues are resolved by the design improvements as implemented by General Electric. Stork closely tracks the design evolution of all Frame Compressors, and has the capabilities to supply these upgraded parts. Our customers' feedback and field experience show that they are very satisfied with the efficiency and longevity of our compressor parts, especially the new 7EA upgraded design. Stork will continue to keep track of any design changes made to these compressors, and continue to provide the highest level of quality that is equivalent or better than the OEM's. Stork is the number one independent provider of Gas- & Steam Turbine Compressor parts, and continuously strives to improve and maintain your assets.

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In 12 Months of Stork

Global Deliveries
Global
Deliveries
91.542
Total blades
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9
Customer
satisfaction
159
Units
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