Safety Integrity Level Analysis

What is a SIL Analysis?

To learn what is a SIL Analysis (or SIL study) it is first best to know that process hazards need risk reduction using a safety instrumented system or safety instrumented functionApplications like this occur in oil & gas upstream and downstream, chemical and pharmaceutical production, power generation, pulp and paper and others.

Applications of SIL rated Systems

  • Emergency shutdown - ESD
  • Process shutdown - PSD
  • Overfill protection on storage tanks
  • Gas turbine shutdown
  • High Integrity Pressure Protection - HIPPS for piping and vessels


  • Chemical production
  • Oil & Gas upstream / downstream
  • Power Generation
  • Pulp & Paper
  • Pharmaceutical production



Determine a SIL Target

Using pre-agreed tolerable risk criteria and a SIL analysis procedure, eFunctionalSafety can lead your SIL study team sessions with one of our highly experienced and senior facilitators.


We support projects using an agreed procedure, whether that is layer of protection analysis (LOPA), risk graph, or a combination of methods.

For Quantfied Risk Analysis (QRA) we have access to IsoGraph FTA software for custom fault tree analysis and event tree analysis.


Write the Safety Requirements Specification

A solid safety requirements specification is the backbone of any safety system. We have proven templates and checklists which have been tested on multiple industry projects. Our service can be as little as checking your requirements are complete, or providing support to author the full requirements specification.


SIL Verification

eFunctionalSafety has access to the know-how, software tools and equipment failure rate data that can model the hardware performance of even the most complex Safety Instrumented Function (SIF) designs. We can support SIL verification using IsoGraph FTA (Fault Tree Analysis) / RBD (Reliability Block Diagrams), exSILentia (exida), and we have individuals with formal training in aeShield (aeSolutions).

CASE STUDY - SIL Verification

gas turbine sil verification

We provided SIL verification support for an entire package of turbomachinery safety functions for a well-known Small Gas Turbine (SGT) supplier.

We reviewed the SIL analysis, supported the authoring of the system and functional safety requirements specification, and provided the probability of failure calculations for every safety function within the gas turbine (GT) range.

Our comprehensive report enabled the GT supplier to demonstrate that the required SIL targets could be met by the hardware design.

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