Initial Situation
A safety valve in an industrial plant was taken out of service due to a severely worn stem. Deep grooves and scratches had rendered the component unusable. Until now, the only option was the time‑consuming and costly procurement of a new stem.
The Challenge
The objective was to restore the stem so that it would again withstand high mechanical loads and corrosive operating conditions over the long term – as quickly and precisely as possible, and without any compromise on quality.
The Solution
Our team selected a laser spray coating process using the proven cobalt‑based alloy STELLITE™ 21.
- The damaged area was first turned down until all grooves were completely removed – even though this meant the diameter was now several millimetres undersize.
- STELLITE™ 21 was then applied by laser spray coating and metallurgically bonded to the component surface.
- After final machining (turning and grinding), the stem surface achieved a roughness of Rz 3–4 and a hardness of up to 50 HRC.
Result
The stem was fully refurbished and returned to service with a robust, wear‑ and corrosion‑resistant surface. The plant operator was able to avoid the high cost and long lead time associated with manufacturing a new part.
Benefits for the Operator
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Significant cost savings through refurbishment instead of new manufacture
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Improved availability compared with complete new production
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Extended service life thanks to a hard, work‑hardened surface
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Increased operational reliability due to optimised surface quality
