Too Good to be TrueFriday, April 13, 2012
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A.K.A You’re About to Severely Under-Design your SIF and Put your People at Risk.
Twice this week alone, and much more often than I like to remember, I’ve had safety system designers blindly follow certificates that contain data that simply cannot be true. They get a certificate from an equipment supplier and stamped by a 3rd party assessor that states the valve or actuator can meet SIL 3 requirements with no redundancy. One certificate actually listed the dangerous failure rate at 3.06 FITS for a scotch yoke actuator, which translates into an average of one dangerous failure in over 37,000 years! Any experienced safety or process engineers should know from experience that this type of performance is not even close…