The Safety Integrity Level (SIL) or the average probability to fail on demand (PFDavg) of each safety instrumented function (SIF) is calculated to verify that each SIF achieves the risk reduction allocated during the hazards identification and risk analysis. Spurious trips have a significant impact on production and cost, so our design and verification process also analyzes the spurious operation rate and optimizes the design to achieve the best overall lifecycle cost.
Methodology: Verification is performed by modeling each SIF using fault tree analysis, which is a highly adaptable logic diagram based technique.
Software: Fault tree analysis is used to calculate the PFDavg and the spurious trip rate of each safety function. The calculation is performed using a SIS-TECH proprietary software tool, SIL Solver®, or Isograph FaultTree+, depending on the complexity of the safety function.
Databases: The SIS-TECH proprietary database provides failure rate data and other reliability parameters.
The SIS-TECH Advantage:
- Comprehensive knowledge of the different calculation methods.
- Standard practices to ensure consistent results.
- Proactive involvement in industry data collection efforts ensures data quality.
- Overall understanding how safety controls, safety alarms, interlocks, SIS, electrical systems and the network are integrated to achieve reliable production.
- Extensive knowledge of reliability engineering.
- Direct experience with installed equipment performance.
- Our calculation methodology and data are transparent.
- Extensive hands on experience with safety protection strategies.
SIS-TECH facilitators have over 20 years of experience in process engineering, operations, and consulting. Every facilitator has received independent professional facilitation skills training. We have experience and advanced skills in many different procedures, including PHA, HAZID, HAZOP, What-if, QRA, LOPA, and FMEA, and are adaptable to different approaches. Our clients tell us that our studies are thorough, involve significantly re-work after the team meeting, and yield more defensible results than our competitors.
- Are competent in process safety management and the requirements of OSHA 1910.119
- Provide a comprehensive and thorough analysis of potential hazards and risk
- Ensure clear and complete documentation of the loss event scenarios
- Identify critical safeguards or IPL needed to manage risk
- Assure that proposed recommendations are credible, practical, and implementable
- Have experience with common industry tools, such as PHAPro, Stature, PHAWorks, Leader, etc.
We facilitate the following types of studies:
- Hazard identification
- Risk analysis
- Risk assessment
- Consequence modeling
- Alarm rationalization
- Facility siting
- Functional safety assessment