December, 2003

200301DecAll DayTrees, trees, confusing treesProcess Safety Beacon | Label all valves and pipes so that their function can be determined easily and quickly.Lessons:Management of Change,Operating ProceduresLanguage:EN Origin: CCPS Document Type:BulletinTopics:Human Factors


In the chemical industry we see the other (piping) “Christmas trees” year-round at work. These “Christmas trees” are actually concentrated concoctions of piping, valves, instruments tubing, gages and fittings. In many cases, these systems were never really “designed,” they just evolved-one valve, one gage, and one instrument at a time. When the changes were originally made in the field, they seemed to make sense; but as time went on, they grew in to a bigger and bigger mess-a dangerous mess!

So, What happened?

In the case on the left, an operator added an incorrect gas to a still by mistakenly opening the wrong valve in the Christmas Tree. Fortunately, this mistake only killed the reaction and no damage was done. But just think what might have happened if an other incompatible chemical had been added .

What Allowed this to Happen?

The real problem is that the Management of Change (MoC) process did not work very well. Operator usability was not considered and the PHA did not recognize the human factors issue–visual confusion added by the changes.

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