Worst place determination

Can any body tell me how to determine worst place for cleaning in process tank ? I know these are the places where the cleaning is not happened properly.
How to rectify the problem of worst case ?

Dear Prashant.chawla,

the worst place for cleaning is usually determined based on the practical experience of the operators who clean the equipment, and theoretical considerations. The worst case locations chosen are the ones that are hardest to access, clean and inspect, where product buildup or remaining residues have been observed, or where product is liable to dry on. More theoretical considerations include locations where rinsewater is collected, where dust during the process may be sucked in but the cleaning agent not (vaccum ports), materials where product may stick on, etc. The more scientific determination is based on an assessment of the risk posed by a contamination present in each location within the equipment, taking into account the solubility or ease of cleaning, for the probability of occurrence, the possibility of contamination of the next batch, for the impact, and the organoleptical detectability and ease of inspection, for the detectability. With the resulting RPN you can rank the locations and conduct prevalidation studies to confirm the assessment and rule out the less critical locations.

For a process tank (I asume a stirred tank with a heating/cooling jacket) the worst case locations include the inlets on the top of the tank, the deflector baffles which aid in stirring (normally they have a face opposed to the manhole, that is difficult to access), the drain/tank outlet, the inner walls of the tank at the height of the upper rim of the heating jacket, (where solution may dry on), mixing paddles (the lower face is difficult to access), and so on.

Best regards