The strength and performance of heat-strengthened and fully tempered glass is greatly affected by the surface and edge stress induced during the heat-treating process.

The edge and surface stress levels are specified in Specification C 1048, in the Engineering Standards Manual of GANA , and in foreign specifications.

Surface stresses can be measured nondestructively using methods, such as Test Method C 1279. The calibration of surface measuring devices used in those procedures and periodic verification of calibration are needed. This test method offers a convenient way to accomplish this task.

1. Scope

1.1 This test method covers calibration or verification of calibration, or both, of surface-stress measuring devices used to measure stress in annealed and heat-strengthened or tempered glass using polariscopic or refractometry based principles.

1.2 This test method is nondestructive.

1.3 This test method uses transmitted light, and therefore, is applicable to light-transmitting glasses.

1.4 This test method is not applicable to chemically tempered glass.

1.5 Using the procedure described, surface stresses can be measured only on the “tin” side of float glass.

1.6 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.

2. Referenced Documents (purchase separately) The documents listed below are referenced within the subject standard but are not provided as part of the standard.

ASTM Standards

C158 Test Methods for Strength of Glass by Flexure (Determination of Modulus of Rupture)

C162 Terminology of Glass and Glass Products

C770 Test Method for Measurement of Glass Stress--Optical Coefficient

C1048 Specification for Heat-Strengthened and Fully Tempered Flat Glass

C1279 Test Method for Non-Destructive Photoelastic Measurement of Edge and Surface Stresses in Annealed, Heat-Strengthened, and Fully Tempered Flat Glass

Keywords

calibration; stress measurements; surface stress; tempered glass; Calibration; Calibration--load testing machines; Stress; Surface-stress measuring devices;

ICS Code

ICS Number Code 17.180.30 (Optical measuring instruments); 81.020 (Processes in the glass and ceramics industries)

Citing ASTM Standards

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