ISO INTERNATIONAL STANDARD 4790 First edition 1992-05-01 ANsi Interat Doc Sec Glass-to-glass sealings --Determination of stresses Soudure verre-verre - Determination des contraintes Referencenumber ISO4790:1992(E) Provided by IHS under license with ISO Copyright International Organization for Standardizatior No reproduction or netwvorking permited without license from IHS Not for Resale ISO 4790:1992(E) Foreword IsO (the International Organization for Standardization) is a worldwide federation of national standards bodies (Iso member bodies). The work of preparing International Standards is normally carried out through Iso technical committees. Each member body interested in a subject for which a technical committee has been established has the right to be represented on that committee. International organizations, govern- mental and non-governmental, in liaison with Iso, also take part in the work. Iso collaborates closely with the International Electrotechnicai Commission (IEC) on all matters of electrotechnical standardization. Draft International Standards adopted by the technical committees are circulated to the member bodies for voting. Publication as an Inter- bodies casting a vote. International Standard isO 4790 was prepared by Technical Committee IsO/TC 48, Laboratory glassware and related apparatus, Sub-Committee sc 5, Quality ofglassware. Annex A of this Internationai Standard is for information only ISO1992 All rights reserved. No part of this publication may be reproduced or utilized in any form or by any means, electronic or mechanical, inciuding photocopying and microfilm, without permission in writing from the publisher. International Organization for Standardization Case Postale 56 . CH-1211 Geneve 20 · Switzerland Printed in Switzerland rnational Organization for Standardization No reproduction or networking permitted without license from IHS Not for Resale INTERNATIONAL STANDARD ISO 4790:1992(E) Glass-to-glass sealings -Determination of stresses 1 Scope sulting from the birefringence, the following equation applies: This International Standard describes the test As method for determining the stresses which may oc- ak ... (1) cur after the sealing of two glasses by means of stress birefringence. where is the tensile or compressive stress; As is the optical path difference; Normative references K is the stress optical coefficient; The following standards contain provisions which through reference in this text, constitute provisions a is the light path in the test specimen of this International Standard. At the time of publi- (which is identical with the height h of the cation, the editions indicated were valid. Aft stan- test specimen). dards are subject to revision, and parties to agreements based on this International Standard are encouraged to investigate the possibility of ap- For positive stress-optical coefficients K, in the case plying the most recent editions of the standards in- dicated below. Members of IEC and ISO maintain of a tensile stress in the glass, the value for As shall registers of currently valid International Standards. have a positive sign (+), and in the case of a compressive stress in the glass a negative sign IsO 10345-1:1992, Glass - Determination of stress- (--). For negative stress-optical coefficients K, the signs of A.s are the contrary. optical coefficient - Part 1: Tensile test. IsO 10345-2:1992, Glass - Determination of stress- optical coefficient - Part 2: Bending test. It is assumed that a plane state of stress is set up predominantly in the test specimen and that the FEPA-Standard 43-GB-1984,1) Standard for coated stress zone in the direction of transmission of light abrasive grains of fused alumina and silicon carbide. in the vicinity of the sealed area is approximately homogenous. The three principal stresses are orientated in such a way that 3Principle the first principal stress o, is perpendicular to the If two glasses are sealed together, stresses can surface of the