Companies often have multiple 'sister' plants in different locations, sometimes scattered around the globe. Generally, these companies are striving for similarly low risk among all these sister plants, even though they may have been built at different times, using evolving technology and often have different capacities. In the pursuit of achieving acceptably low risk at all the chemical plants within a company, Process Safety specialists tend to put each under the PHA 'microscope' separately. FMC has several businesses that operate multiple "sister" plants, and has found that there are substantial benefits to be gained by also comparing the hazards at similar plants. (C) 2009 American Institute of Chemical Engineers Process Saf Prog 29: 64-69, 2010