Step 4 SIS Design and Engineering

Safety lifecycle phase or activity Objectives Requirements Clause or Subclause of ISA-84.01-2004 Inputs Outputs 

This clause lists some of the key parameters employed when selecting the technologies and components 

Plant PHA team approves all devices used in SIS service Low complexity devices with plant familiarity SIL claim limit with documented source 

Maintenance and testing philosophy consistent with plant personnel capability/experience Operator/maintenance interface based on existing plant criteria Cost and schedule per project estimates and timing respectively Use of BPCS for application software diversity (shadowing) 

All technology selected has been previously used on plant and is well understood by plant maintenance personnel 

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