Page review information
Edition covered
IEC 61511 · IEC 61508 — exact governing revisions not yet recorded — verify on the linked standards pages
Content status
Reviewed
Coverage
SIS/ESD routing scenario; application-vs-foundation split summarized, SIL work not performed here.
Last reviewed
August 2026
Primary reference
The official published standard — required for final decisions

Confirm the governing edition, jurisdiction, and project-specific requirements before applying anything on this page.

Scenario 03

Process Skid Shutdown System

Project Summary

Field Detail
Application Process skid with SIS / ESD (Emergency Shutdown) system
Industry Process industry — oil and gas, chemicals, or similar
Safety standard IEC 61511 (application) + IEC 61508 (foundation)
Corpus coverage IEC 61511 and IEC 61508 functional-safety pages are present; IEC 60079 coverage is available for hazardous-area routing

Important note: The project reference library covers the IEC 61511 routing and lifecycle basics needed to place a process skid on the correct standards path. Project SIL calculations, proof-test intervals, and hazardous-area design details still need direct engineering verification against the published standards and the plant basis of design.

Starting Standards

Standard Role Status
IEC 61511 2016 SIS application standard for process industry Reviewed
IEC 61508 2010 Foundation safety lifecycle standard Reviewed
NEC / local code Electrical installation Review pending
IEC 60204-1 Machine electrical (if machine elements present) Review pending

Standards Decision Logic

Process skid with shutdown system:
  ├── IEC 61511   → SIS application standard (HAZOP → LOPA → SIL → SIF design)
  ├── IEC 61508   → Foundation lifecycle (referenced by IEC 61511)
  ├── IEC 60079   → If hazardous area (classified location)
  └── NEC hazardous location articles → US installation

SIS Lifecycle Overview

Per IEC 61511, the SIS lifecycle includes:

  1. Hazard and risk analysis (HAZOP)
  2. Safety requirements specification
  3. SIL determination (LOPA or risk graph)
  4. Safety system design (SIF allocation)
  5. Installation and commissioning
  6. Operation and maintenance (proof testing)
  7. Decommissioning

Key Concepts

SIF (Safety Instrumented Function): A safety function implemented by the SIS. One SIS may have multiple SIFs, each with its own SIL target and proof test interval.

PFDavg (Average Probability of Failure on Demand): The key reliability metric for SIS/SIF. SIL target determines the required PFDavg range.

LOPA (Layer of Protection Analysis): Most common SIL determination method in process industry. Credits independent protection layers (IPLs) against the demand rate to determine required SIL.

Repository Paths

Standard Repository Path
IEC 61511 rag/international/functional_safety/iec_61511/
IEC 60079 rag/international/hazardous_area/iec_60079/
Scenario reference rag/scenario/mini_machine_safety_design/

Limitations

See Petroleum / Oil & Gas industry overlay →

Trust Boundary — Engineering Judgment Required

This site is an independent educational reference for industrial automation standards. It paraphrases and organizes guidance in original language; it is not a substitute for the official published standards, professional engineering judgment, or legal review, and content has not been independently verified against current published editions.

Items marked Review pending await technical review against the identified edition. Items marked Planned have no reviewed source material behind them. Do not rely on this site for compliance determinations, safety-critical design decisions, or legal interpretation.