Tempered & Heat-Treated Glass
ITI Glass produces quality heat-treated glass on one of the largest furnaces in the United States. Advanced controls produce an extremely flat glass with optimal visual clarity.
With one of the largest tempering ovens in the nation, building designers are no longer held back by heat-treated glass production limitations. ITI Glass' oversize Glassrobots® tempering furnace manufactures heat-treated glass up to 100 inches x 180 inches. The furnace, installed in November 2006, incorporates advanced computerized controls capable of producing heat-treated glass with superior visual clarity and minimal roll-wave distortion.
Inside ITI Glass’ furnace, glass oscillates forward and back on ceramic rollers. Constant motion during the heat-treating process reduces the visible effects of roll-wave distortion. Convection heating focuses heat directly on the glass, resulting in a faster, more efficient heat-treating process.
ITI Glass manufactures heat-treated glass according to ASTM C1048–04 and certifies all safety tempered glass in compliance with ANSI Z97.1–2004 and CPSC 16 CFR 1201 Category 2 standards.
Safety Tempered Glass
Tempered glass is used in a variety of safety glazing applications, including storefronts, interior glass walls and glass doors. The product is four times stronger than annealed glass of equal thickness and shatters upon breakage, meeting most safety glazing requirements. At ITI Glass, tempered glass is heated to 1400-degrees Fahrenheit in an electric furnace. After heating, the glass moves to the quench where it is rapidly chilled by a burst of air. Rapid cooling after the heating process leaves the glass surface in a state of compression and its core in a state of tension. The difference between the surface and core pressures causes the glass to shatter in small pieces when broken.
Heat-Strengthened Glass
Heat-strengthening is often specified to reduce the risk of spontaneous breakage by thermal and mechanical stresses related to surface area and application sizes. Like the tempering process, heat-strengthening begins by heating glass in ITI Glass' electric furnace to 1400-degrees Fahrenheit. After which, glass passes to the quench and is gradually cooled resulting in a stronger product with a breakage pattern similar to annealed glass. Heat-strengthened glass is two times stronger than annealed glass of equal thickness. Due to its breakage pattern, the product is not used for safety glazing applications.
Note on Roller-Wave Distortion and Sample Specification
During the heat-treating process, some amount of visible roller-wave distortion occurs as glass is heated, cooled and conveyed on ceramic rollers. With advanced computerized controls and skilled processing procedures, ITI Glass can produce heat-treated glass with minimal roller-wave distortion, resulting in an extremely flat glass with optimal visual clarity.
Many glass manufacturers recommend including the specification below to minimize the appearance of roller-wave distortion in heat-treated float glass:
All heat-treated and fully-tempered glass shall be fabricated by horizontal process to show roller-wave distortion running parallel to the bottom edge of installed glass (unless otherwise noted in these documents or drawings). Distortion shall fall within this accepted tolerance: A maximum of 0.005 inch from peak to valley in the center of glass, and a maximum of 0.0100 inch from peak to valley within 10-1/2 inches of the leading and/or trailing edges of the glass.
ITI Glass has established an in-house quality control program to manage the faltness of its heat-treated glass. For projects requiring tighter roller-wave tolerances or production documentation, ITI Glass can issue a project-specific document stating that glass has been produced and analyzed to meet a specific roller wave tolerance. Contact ITI Glass for more information.
