Case Study

The Royal Mint Inspection and cleaning of a Coin Annealing Rotary Furnace section

Inspection and cleaning of a coin annealing rotary furnace section


The Royal Mint had a requirement to undertake a conditional appraisal on a retort (scroll) that forms part of a Coin Annealing Rotary Furnace. As a result of the Brass annealing process, Zinc Oxide has gathered within the retort since the machine become operational three years prior to the inspection.


The inspection was undertaken from the open end of Seco Warwick Retort. Simultaneous warehouse operations were being carried out in the general work area as per normal site operations. All electrical equipment was tested by an Inspectahire electrician and verified that it was fit for use. The P448 Explosion Proof Crawler/Tractor with Pearpoint P494 Camera with a full 360° pan and tilt for maximum viewing capacity was energised and tested. The Tractor was then inserted into the Seco Warwick Retort and a preclean inspection of the Retort up to 19 metres where the propeller type assembly stopped any further progress of the P448 Camera System.

The P448 Tractor was then fitted with the BJV Rotating Jet Head and a cleaning run at 20,000 psi was conducted. After the Tractor System had done a couple of runs back and forth along the Retort a further camera inspection was undertaken. This process was then repeated with a stepping up of pressure to 27,000 psi and then 32,000 psi. The survey was recorded onto mini digital tape to be reviewed by Inspectahire upon return to Aberdeen.


The Retort was cleaned and inspected from the start to approximately 18.6 metres where the propeller type assembly stopped the cleaning operations. The majority of the debris/coating within the Retort was removed during the cleaning operation. A few areas still had some Brass type coating and blanks attached to the inner surface.