A company decided to stop making a chemical product. One of the input materials was toxic and corrosive phosphorus trichloride (PCl3). The lines to the storage tank and the process area were cleared of PCl3 . A few years later, an operator found a leak outdoors. The investigation found that the leak was coming from the “empty” PCl3 line. No one was injured and the spill was contained.
During the clearing and flushing steps to shut down the PCl3 facility, someone missed clearing or flushing that section of line. It took a while, but the material corroded the “empty” pipe and caused a release.
We think of catastrophic incidents as occurring quickly like an explosion. However, many serious incidents have occurred months or even years after a mistake was made.
An operator may have mistakenly opened the wrong valve, realized the mistake closed it, but never told anyone. Did some material pass through in that short time? What happens or when it will occur is difficult to predict, but it could cause a serious problem.
Or take another example: A maintenance technician is replacing the seal on a pump. T he wrong seal is picked up in the stockroom and installed. When put into service, it may take some more time for the incorrect seal to fail. The incorrect seal will probably fail before the correct one.
An error now may cause a disaster in the future !