The Situation

A dairy company contacted Qualtex with an urgent concern: a critical HVAC fan in their cheese plant was experiencing escalating vibration levels. A failure of this fan would have directly impacted plant operations and product output.

The Challenge

Initial on-site diagnostics confirmed the elevated vibration and identified an additional concern — an intermittent mechanical clicking noise that raised the possibility of a cracked main shaft. If correct, the risk of catastrophic in-service failure was real.

Removing the fan for further investigation presented its own challenge. The fan components — impellers at 1850mm in diameter and the main shaft assembly — had to be extracted through very limited access within the HVAC room. This required careful planning before any physical work could begin.

What Qualtex Did

Qualtex technicians conducted vibration analysis to confirm the fault, then worked with the client to agree a removal methodology. Scaffolding was erected and cranage organised within a few days. The fan was disassembled and components transported to the Qualtex workshop in Hamilton.

Non-destructive testing confirmed the presence of a crack in the 150mm main shaft, located just below one of the impeller hub seats. Material analysis was conducted to ensure a matching specification for the replacement shaft, which was then manufactured.

Once the new shaft was complete, hubs and impellers were fitted and the full assembly dynamically balanced on our workshop machine to ISO 1940 Grade G2.5. The unit was returned to site, reassembled, and a final in-situ balance check performed using Schenck mobile balancing equipment before commissioning.

The Outcome

The fan was returned to service with vibration levels within acceptable limits and the root cause — a cracked shaft that would have caused a catastrophic in-service failure — fully resolved. The client had visibility of every step of the process, from initial diagnosis through to sign-off. The methodical approach, including NDT confirmation