voestalpine Böhler Welding
voestalpine Böhler Welding

Rectification of cracks in penstock

Phoenix Nautica 20 and BÖHLER FOX 85/65

voestalpine Böhler Welding India supported the project of national (India) importance, the “KAMENG HYDRO ELECTRIC PLANT” of North Eastern Electric Power Corporation Limited (NEEPCO) by supporting the contractor for repair welding of penstocks which not only had posed a serious threat but also developed to be an extreme challenge in repair welding.

The project comprises of two dams and water is transported through a Head Race Tunnel (HRT) & Penstock (HPT) into the Kimi Power House for driving 4 Vertical Frances Turbines,150 MW each. When water was released from the dam, it started leaking from multiple places of the penstock which further on led to cracks in the HPT.

Accumulating challenges

Approximately half of the number of weld joints were found to be defective and the defects were found in:

  • Water leakage through grout plugs
  • Cracks & Pinholes in weld joints
  • Offsets in weld joints

As the penstocks were under concrete roofing and under rocks/mountains, there were very limited chances of any repeated repairs or replacements. Therefore, all the welding repair had to be done in one go. The team of voestalpine Böhler Welding India recreated the customer application and problems in a simulation at their ATC to perform mock-up trials and after successful in-house trials submitted two of their best-in-class stick electrodesPhoenix Nautica 20“ and „Böhler FOX EV 85/65“ along with a WPS to the customer.

Welding in wet environment can be regarded as a procedure that is much more difficult to operate. It requires trained welders with high practical skills, excellent knowledge and an extremely high amount of concentration on the job during the whole operation. Therefore, additionally to the materials, voestalpine Böhler Welding India provided special training for the involved welders in the project, to operate the consumables in the perfect and most efficient way.

CUSTOMER BENEFITS

  • Reduction of lead time in the repair procedure
  • Cost savings due to higher efficiency
  • Repair PQR qualified

Find the entire success story together with technical details and customer benefits in the download area or here: