Claus, one of our challenges is evaluating the risk of a rundown line failure versus the cost of preventing it or mitigating it. We have a single 4″x6″ jacketed rundown line about 1/2 mile long between our sulfur pits and our storage tanks/rail loading unit. Loss of this line would shut down the refinery. Replacing the line/ adding a redundant line is ~$3,000,000. It’s carbon steel piping with 70# steam tracing on the jacket. Theoretically, there are very few damage mechanisms in these services. Loss of steam appears to be the main probable reason for loss of the line, although contaminants and poor steam quality have also been identified. The problem becomes, how do you evalaute the probability of a failure? What are other people doing for reliability strategies around rundown lines?
