ISO 12540:2017

Overview - ISO 12540:2017 (Tempered soda lime silicate safety glass)

ISO 12540:2017 is the international product standard for flat tempered (thermally toughened) soda lime silicate safety glass used in building applications. It defines product definitions and the required product characteristics - including tolerances, flatness, edgework and fracture/fragmentation behaviour - and specifies physical and mechanical characteristics relevant to safety glass performance. The standard applies to flat panes only and does not cover curved (bent) glass (see ISO 11485). Additional requirements for laminated or insulated assemblies or coated glass are covered by the appropriate product standards.

Key topics and technical requirements

ISO 12540:2017 addresses the full manufacturing and quality control spectrum for flat tempered safety glass:

• Product definitions and terminology (e.g., horizontal, vertical, air cushion tempering; enamelled tempered glass).
• Dimensions and tolerances: nominal thickness, thickness tolerances, width/length limits, squareness and edge deformation produced by tempering processes.
• Flatness and optical characteristics: measurement and limits for overall bow, roller/wave distortion, edge lift (horizontal tempering), perimeter deformation (air cushion process) and local distortion (vertical tempering).
• Edge work, holes, notches and cut-outs: permitted edge treatments, hole diameters, positions and tolerances, and requirements for profiled or shaped panes prior to tempering.
• Fracture and fragmentation: fragmentation test methods, specimen dimensions, particle counting and assessment, and maximum acceptable particle sizes to characterize breakage behaviour.
• Physical/mechanical properties: thermal durability, mechanical strength (referenced test methods), surface pre-stress measurement, anisotropy (iridescence) and optical distortion.
• Marking and packaging: identification and handling requirements for tempered safety glass.
• Test methods and annexes: includes pendulum impact methods (Annex A), alternative measurement techniques (Annex B), example particle counts (Annex C) and surface pre-stress measurement (Annex D).

Applications and who uses this standard

ISO 12540:2017 is used by:

• Glass manufacturers and tempering plants for product specification, production control and conformity assessment.
• Architectural and façade designers, façade engineers and specifiers selecting tempered safety glass for doors, windows, partitions, balustrades, shower enclosures and curtain walls.
• Test laboratories and quality assurance teams conducting fragmentation, impact and flatness testing.
• Building authorities, safety consultants and procurement teams who require compliance with recognized safety glass performance criteria.

Practical benefits include consistent product quality, predictable breakage behaviour, correct dimensional tolerances for assembly and enhanced safety performance in buildings.

Related standards

• ISO 11485 - Bent (curved) glass (excluded from ISO 12540)
• ISO 29584 - Pendulum impact testing and classification of safety glass
• ISO 1288-3 - Bending strength test method (four-point/flexure)
• ISO 16293 series - Basic soda lime silicate glass definitions and properties

Keywords: ISO 12540:2017, tempered safety glass, soda lime silicate, flat tempered glass, fragmentation, glass tolerances, flatness, edgework, glass in building.