Refurbishing and overhauling a ball valve in Vernayaz for the Swiss Federal Railways
The discovery of a leak led to HYDRO carrying out an overhaul of a ball valve. Following the refurbishment, the safety device is watertight and has been treated against corrosion.
An inspection of Swiss Federal Railways installations in Vernayaz revealed leaks on a DN750 / PN75 / Gr1 ball valve. Following in-depth discussions with the customer, it was decided to dismantle on site, followed by a fuller dismantling of the parts concerned at the central workshops in Martigny, which are renowned for their skills and expertise.
Under the microscope at the central workshops
The dismantling by HYDRO’s RMM Mechanical Overhaul and Assembly team in collaboration with the Federal Railways’ mechanical team in Vernayaz meant that the valve could then be transferred to the workshop for detailed analysis. Tests carried out before and after dismantling revealed that the valve was geometrically misaligned. This affected its functioning. Moreover, the sealing cuffs and grooves were suboptimal and not watertight.
In consultation with the customer, solutions were proposed and confirmed. Once the valve had arrived at the Martigny workshops, amendments were made to correct the geometric alignment by adjusting the bearing clearance. The defective sealing cuffs were replaced with custom parts sourced from another supplier, and all the other O-ring seals were changed.
Guaranteed watertight
An anti-corrosion coating was also reapplied to the two hemispheres and the shutter to ensure optimum corrosion protection over time. Once the parts had been meticulously prepared, the valve was reassembled and pressure tested in the presence of the customer. The results confirmed it was 100% watertight.
Finally, the valve was reinstalled on the Federal Railways site and successfully commissioned. The client was delighted with the quality of the intervention and the results obtained and expressed their gratitude for the precision of the work.
