Non-destructive testing (NDT) is used to verify that there are no internal defects, more specifically, cracks, in equipment and machines, without altering them.

NDT is carried out during the manufacture of a part or the refurbishment of a mechanism to show what condition the material is in. It is also possible to evaluate the condition of a component in a production machine on site. This way, the owner can assess and plan the necessary preventive or corrective maintenance for his installations.
This service can also be used to validate welding work, approve the quality of raw materials before they are machined and verify any internal corrosion by taking ultrasonic thickness measurements.


An array of inspection methods allow our certified specialists to evaluate the quality of a material :

  • visual testing (VT) provides essential information on the external condition of a part to determine any obvious defects such as wear, corrosion and open cracks.
  • penetrant testing (PT) involves applying a red liquid penetrant to the surface of the test piece and allowing it to enter any cavities. After the excess penetrant liquid has been removed from the surface, a white developer is applied to draw out the liquid trapped in the openings and cracks by way of the capillary action principle. This method reveals any surface-breaking discontinuities with an opening of 1 m or 100 times thinner than a strand of hair.
  • magnetic particle testing (MT) is used to detect surface and slightly subsurface flaws by applying a magnetic developer and then magnetizing the metal part to saturation. This process can only be used on ferromagnetic materials such as steel, cast iron, nickel and cobalt.
  • ultrasonic testing (UT) is used for detecting flaws inside the the material. It works off the transmission and reflection of ultrasonic waveforms inside a material.
  • radiographic testing (RT) is mainly used for checking weld seams; it provides feedback about the internal structure of a part that can then be quickly implemented. Although we do not have the equipment to carry out such checks in-house, we work in close collaboration with specialists in this area.

Specific skills

Our client benefits from the following advantages :

  • an accurate report on the condition of the mechanical part, its level of wear and its potential remaining service life.
  • the owner can plan essential preventive or corrective maintenance.
  • all the servicing of mechanical components under one roof at our Central Workshops.

Additional services
Central workshops
Set up at the Martigny site in 2007, the Central Workshops bring together our skills in the servicing of mechanical components. The knowledge we have acquired in the operation of hydroelectric plants qualify us to fulfil our clients’ needs and provide them with tailored solutions.
Servicing of mechanical components
Servicing the mechanical components is an integral part of operating a hydroelectric plant and the work is carried out at the intervals specified in the owner’s maintenance schedules. This service focuses on the inspection of large-diameter safety equipment, such as globe valves, butterfly valves, injectors, pumps and Francis turbines. Multiple skills are required and they permit the complete servicing of safety equipment according to the supplier’s requirements.
Renovation of wheels
This Workshop brings together all the skills previously sourced from the former Alp Hydro facilities at Chippis and the Grande Dixence workshops of Les Haudères and Z’Mutt under one roof at Martigny. Our colleagues provide all the services needed to maintain and service impellers and turbine wheels (Francis, Pelton, Kaplan), as well as their component parts, whatever their dimensions. This work is carried out in Martigny, but can also be done on site, for example, for polishing a turbine wheel.
Machine Shop
Since 2007 and its set-up at the Martigny site, this Workshop has brought together all of our machining skills under one roof. Its sole purpose is to manufacture various parts to support the servicing of mechanical components and spare parts. Thanks to its constant expansion, in particular with the acquisition of the new CORREA machining centre facilitating dimensions unique in the French-speaking part of Switzerland, we are able to fulfil the many demands of different clients.
Welding activities
Hydroelectric production equipment is largely made up of joint welded parts. Each welding process requires a high level of skill to ensure that the installations function properly and safely.
Rue de l’Industrie 10, 1951 Sion
HYDRO Exploitation SA
Rue de l’Industrie 10
CP 315 - CH-1951 Sion
Contact us
HYDRO Exploitation SA
Rue de l’Industrie 10 CP 750 - CH-1951 Sion +41 (0)27 328 44 11
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