Walking the plant is an essential skill that can be learned, but it is one that also benefits from years of experience. Its purpose is to make a detailed study of the plant to determine the areas that are at the greatest risk for cross contamination. No feature should be left unquestioned in this process. Walking the plant requires the inspection team to look at everything with a fresh and critical eye, paying special attention to risk areas such as:
[COLOR=“blue”]awkward crevices and corners;
service lines, particularly nitrogen and vacuum;
dead ends;
condenser reflux lines;
screw mechanisms;
lines that slope uphill to a vessel;
filter meshes;
valves;
sampling equipment; and
seals and gaskets. [/color]
A careful and thorough walk-through conducted by a qualified team will certainly help prevent contamination issues, but the team must have the wider support of the company in order for its findings to be acted on. A thorough inspection will almost certainly identify aspects of plant design that need modification. When possible, it is preferable to “engineer out” the problem areas; the short-term expense in plant design will have long-term benefits in removing problem areas.
The inspection should also determine areas of the plant that may need to be dismantled and inspected following cleaning, while at the same time identifying items that should be manually cleaned rather than cleaned in place.