ISO 13577-4:2022

Overview

ISO 13577-4:2022 - "Industrial furnaces and associated processing equipment - Safety - Part 4: Protective systems" defines requirements for protective systems used with industrial furnaces and associated processing equipment (TPE). This second-edition (2022) part of the ISO 13577 series focuses on safety-related control systems (SCS) and instrumented protective functions (sensors, logic solvers, final elements). It is intended to be used jointly with ISO 13577‑1, ‑2 and ‑3 and aligns with functional safety frameworks such as IEC 61511, IEC 61508, IEC 62061 and ISO 13849‑1.

Note: ISO 13577‑4:2022 excludes blast furnaces, converters, boilers, fired heaters in petrochemical/chemical sectors, electrical cabling upstream of the TPE control panel, and protective systems manufactured before its publication.

Key topics and technical requirements

• Design requirements for equipment in a protective system - robustness, electrical installation compliance (IEC 60204‑1), and resistance to identified operating stresses and hazards.
• Protective system methods - selection among the document’s methods (Method A, combined Method BC, Method D) for designing protective functions; Method BC is a consolidation of previous B and C options.
• Fault assessment and diagnostics - requirements for wired sections, failure modes and fault-tolerant design.
• Failure of utilities and reset procedures - handling utility interruptions and safe reset behavior after actuations or faults.
• Information for use - documentation, marking and instructions for operation and maintenance.
• Normative wiring and software requirements - Annex B (normative) covers wiring practices; Annex F (normative) defines application software requirements.
• Safety integrity and performance level guidance - Annex C provides SIL/PL determination examples (risk graph method); Annex D gives a worked example using IEC 61511; Annex E supplies protective function examples.
• Supportive guidance - Annex A explains techniques to avoid systematic faults.

Practical applications

ISO 13577-4 is applied to the safety design and verification of protective (safety-related) control systems for industrial furnaces and thermoprocessing equipment. Typical uses:

• Defining and documenting protective functions and required SIL/PL for furnace safety interlocks
• Specifying wiring, sensors (e.g., flame detectors), logic solvers (PLCs, safety controllers) and final elements (valves, contactors)
• Performing risk assessments and selecting appropriate safety architectures and diagnostic measures
• Preparing user information, maintenance and reset procedures

Who should use this standard

• Furnace and TPE manufacturers and designers
• Functional safety engineers and control system integrators
• Plant safety managers, maintenance teams and compliance officers
• Certification bodies assessing furnace protective systems

Related standards (examples)

• ISO 13577‑1/‑2/‑3 (series)
• IEC 61511, IEC 61508, IEC 62061, ISO 13849‑1
• IEC 60204‑1, IEC 61131‑3

Keywords: ISO 13577-4:2022, industrial furnaces, protective systems, safety-related control systems, SIL, PL, risk assessment, wiring, flame detector, logic solver, TPE.