ISO 20657:2017 PDF

Overview

ISO 20657:2017 - "Glass in building - Heat soaked tempered soda lime silicate safety glass" defines product requirements and test methods for flat heat soaked tempered (thermally toughened) soda lime silicate safety glass used in buildings. The standard covers product definitions, dimensional and optical tolerances, edgework, fragmentation and fracture characteristics, physical and mechanical properties, manufacturing processes (tempering and heat soak cycles), marking and packaging. It explicitly does not cover curved (bent) glass (see ISO 11485).

Key topics and requirements

• Product definitions and scope for flat heat‑soaked tempered safety glass.
• Manufacturing processes: tempering methods and both off‑line and in‑line heat soak process cycles.
• Fracture and fragmentation: criteria for breakage behaviour, fragmentation testing and minimum particle counts.
• Dimensions and tolerances: thickness, width/length limits, squareness, flatness (bow, roller wave, edge lift, local distortion) and related measurement methods.
• Edgework, holes and cut‑outs: permitted edge profiles, hole diameters, position limits and tolerances for processing before tempering.
• Physical characteristics: optical distortion, anisotropy (iridescence), thermal durability, mechanical strength and surface pre‑stress measurement.
• Testing and annexes: fragmentation test procedures, pendulum impact methods, particle count examples, surface pre‑stress measurement, in‑line heat soak process control and calibration tests.
• Marking and packaging requirements to support traceability and safe handling.

Applications and users

ISO 20657:2017 is intended for anyone specifying, producing, testing or installing safety glass in buildings:

• Glass manufacturers and tempering/heat‑soak processors (product and process control).
• Façade engineers, architects and specifiers selecting safety glazing for façades, balustrades, doors and interior partitions.
• Glazing contractors and installers ensuring compliance with dimensional and edgework requirements.
• Testing laboratories and certification bodies performing fragmentation, impact, thermal and pre‑stress tests.
• Regulators, building inspectors and product certifiers assessing conformity and safety performance.

Note: When heat‑soaked tempered glass is incorporated into laminated assemblies or insulating glass units, additional product standards apply without changing the base mechanical/thermal characteristics specified by ISO 20657.

Related standards

• ISO 11485 - curved (bent) heat‑soaked tempered glass (excluded from ISO 20657).
• ISO 1288‑3 - referenced for bending strength testing.
• ISO/TC 160/SC 2 work - design strength standards for glass in buildings.

Keywords: ISO 20657:2017, heat soaked tempered glass, soda lime silicate safety glass, fragmentation test, flatness tolerances, heat soak process, glass in building.