ISO INTERNATIONAL STANDARD 21922 First edition 2021-08 Refrigerating systems and heat pumps - Valves - Requirements, testing and marking Systemes de réfrigération et pompes a chaleur Robinetterie - Exigences, essais et marquage Reference number ISO 21922:2021(E) ISO @IS02021 IS0 21922:2021(E) COPYRIGHT PROTECTED DOCUMENT @ iS0 2021 All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting on the internet or an intranet, without prior written permission. Permission can be requested from either IsO at the address below or Iso's member body in the country of the requester. ISO copyright office CP 401 · Ch. de Blandonnet 8 CH-1214 Vernier, Geneva Phone: +41 22 749 0111 Email: [email protected] Website: www.iso.org Published in Switzerland i @ IS0 2021 - All rights reserved IS0 21922:2021(E) Contents Page Foreword .V Introduction. ..vi 1 Scope. .1 2 Normative references. ..1 3 Terms and definitions 1 4 List of symbols .4 5 General requirements. 6 5.1 Installation and operation. 6 5.2 Components under pressure 6 5.3 Excessive mechanical stress. 7 5.4 Tightness. 7 5.5 Functioning of hand-operated valves. .7 5.6 Functioning of actuator-operated valves 7 6 Materials. .7 6.1 General. 7 6.1.1 Using metallic materials 7 6.1.2 Using non-metallic materials 7 6.2 Requirements for materials to be used for pressure bearing parts .8 6.3 Compatibility of connections. 8 6.4 Ductility. .8 6.5 Ageing. .8 6.6 Castings. 8 6.7 Forged and welded components. .8 6.8 Nuts, bolts and screws. 8 6.9 Spindles. .9 6.10 Glass materials 9 6.11 Requirements for documentation .9 6.12 Impact energy KV measurement on sub-sized specimens 10 7 Design .10 7.1 General. .10 7.2 Maximum allowable pressure. .11 7.3 Valve and valve assembly strength design 11 7.4 Bodies and bonnets. 12 7.5 Nuts, bolts, screws, fasteners and seals 12 7.6 Seat tightness 12 7.6.1 General. 12 7.6.2 Seat tightness: type test. .13 7.7 Screwed spindles and shafts 14 7.8 Design of glands 14 7.9 Valve seats 15 7.10 Caps. .15 7.11 Hand operated valves 16 7.12 Corrosion protection. .16 8 Appropriate manufacturing procedures. .16 9 Production testing. ..17 9.1 Strength pressure testing. .17 9.2 Tightness testing .17 9.3 Seat sealing capacity .18 9.4 Caps. 18 10 Marking and additional information .18 @ IS0 2021 - All rights reserved ii IS0 21922:2021(E) 10.1 General. .18 10.2 Marking 19 10.3 Example how to mark the allowable limits of pressure and temperature .19 10.4 Hand-operated regulating valves .19 10.5 Caps. .19 11 Documentation .20 11.1 General 20 11.2 Documentation for valves .20 11.3 Additionaldocumentationforvalveassemblies .20 Annex A (normative) Procedure for the design of a valve by calculation .21 Annex B (normative) Experimental design method for valves .24 Annex C (normative) Determination of the allowable pressure at the maximum operating temperature .28 Annex D (normative) Determination of the allowable pressure at minimum operating temperatureRequirementstoavoidbrittlefracture. ..29 Annex E (informative) Compilation of material characteristics of frequently used materials ...40 Annex F (informative) Justification of the individual methods .60 Annex G (normative) Pressure strength verification of valve assemblies ..6 Annex H (normative) Determination of category for valves. Annex I (informative) DN system ..72 Annex J (normative) Additional requirements - Sight glasses and indicators ..75 Annex K (normative) Compatibility screening test. ..78 Annex L (informative) Stress corrosion cracking ..82 Annex M (normative) Method for sizing the operating element of hand-operated valves ..85 Bibliography ..87 iv @ IS0 2021 - All rights reserved IS0 21922:2021(E) Foreword IsO (the International Organization for Standardization) is a worldwide federation of national standards bodies (IsO member bodi