Creating innovative in-place machining solutions that minimise asset downtime and repair costs is what Goltens is known for and has been doing for over 75 years. So when Shanghai Waigaoqiao Power Plant II approached Goltens for an in-place solution to recondition steam valve seats, Goltens stepped up to the challenge.
The plant’s two 900 MW Siemens THDF 125/67 coal-fired supercritical thermal units each had two HPSV, HPCV, ISV, and ICV valve seats that required renewal. The challenge was to machine the original material and remetal the seats in place before machining them back to their original size.
Solution development
Goltens produced a detailed procedure and reviewed it with the customer before mobilising for the job Goltens proposed a detailed solution using its traditional in-place machining coupled with a low surface temperature laser cladding technology.
To prove the viability of the proposed repair, the repair process was tested on a scrap valve in Goltens’ Shanghai facilities. Based on the test results, modifications were made to the equipment to allow a smooth and delay-free job once on site. Goltens then produced a detailed procedure and reviewed it with the customer before mobilising for the job.
Repair scope
For each of the HPSV, HPCV, ISV, and ICV valves, the repairs consisted of:
- Pre-machining the valve seat
- Laser cladding with basic material (X10CrMoVNb9)
- Coating the cladding surface with EOS Nickel Alloy In625
- Finish machining the valve seat to the original dimension
Early completion of the repairs
Goltens’ team completed the job in 32 days, delivering the completed valves back to the customer 6 days earlier than planned.
The work delivered by Goltens Shanghai makes them the preferred choice for upcoming follow on work at Shanghai Waigaoqiao Power Plant III.