I am not aware of any standard that specifically defines the requirements for this practice to ensure that valves are either kept open or closed as needed. I believe it is up to each company to establish its own requirements. You can find more information via a previous Ask the Expert question: http://www.chemicalprocessing.com/experts/answers/2006/019.html

Additionally, there is also information at:

http://www.cheresources.com/invision/index.php?/topic/1351-please-help/

http://webwormcpt.blogspot.com/2008/04/how-cso-and-csc-helps.html

http://cr4.globalspec.com/thread/20417