Qualtex technicians were dispatched to the site and conducted various diagnostic checks confirming the high vibrations using vibration analysis equipment. During their investigations the technicians also discovered an intermittent mechanical ‘clicking’ noise, raising their suspicion of a possible cracked main fan shaft.

Acknowledging the potential catastrophic impact of this on plant operations, Qualtex and the customer agreed to remove the fan for further testing at Qualtex workshops. But this wasn’t to be a simple task by any means. A major challenge posed in removing the large fan components from the HVAC room was the very limited space through which everything could fit to move the large items to the outside of the building. The team worked closely with the customer to make a plan that would enable the safe extraction of all items.

Scaffolding was erected, and cranage organised within a few days. The Qualtex technicians were then able to disassemble the fan unit and remove the individual components; fan impellors – at 1850mm in diameter – and main shaft with fan hubs attached, transporting them off site to the main Qualtex workshop where a detailed scope of work was established.  This included conducting non-destructive testing, which confirmed the presence of a crack in the main 150mm diameter shaft, just under where one of the fan impeller hubs is seated.

In a collaborative effort, Qualtex involved the customer in all aspect of the inspection and repair planning process, proposing a repair methodology and subsequent pricing for approval. Regular updates were provided to the customer, ensuring transparency in progress of the project, and addressing developments in the scope promptly.

Subsequently, the existing shaft was analysed for material type and a new shaft manufactured. Once the new shaft was completed, the hubs and impellors were fitted, and the entire assembly was dynamically balanced on the Qualtex balancing machine to ISO 1940 grade G2.5.

The fan unit was then returned to the site and reassembled. Qualtex technicians performed in-situ balance checks on the fan using their mobile Schenck balancing equipment. The unit was then fully commissioned and handed over to a delighted and grateful customer.