1、BSI Standards PublicationBS EN ISO 28721-5:2016Vitreous and porcelain enamels Glass-lined apparatus forprocess plantsPart 5: Presentation and characterisation ofdefectsBS EN ISO 28721-5:2016 BRITISH STANDARDNational forewordThis British Standard is the UK implementation of EN ISO 28721-5:2016. The U
2、K participation in its preparation was entrusted to Technical Committee STI/36, Vitreous enamel coatings.A list of organizations represented on this committee can be obtained on request to its secretary.This publication does not purport to include all the necessary provisions of a contract. Users ar
3、e responsible for its correct application. The British Standards Institution 2016.Published by BSI Standards Limited 2016ISBN 978 0 580 83083 9 ICS 25.220.50 Compliance with a British Standard cannot confer immunity from legal obligations.This British Standard was published under the authority of th
4、e Standards Policy and Strategy Committee on 31 March 2016.Amendments/corrigenda issued since publicationDate Text affectedEUROPEAN STANDARD NORME EUROPENNE EUROPISCHE NORMEN ISO 28721-5 March 2016 ICS 25.220.50 English Version Vitreous and porcelain enamels - Glass-lined apparatus for process plant
5、s - Part 5: Presentation and characterisation of defects (ISO 28721-5:2016) Emaux vitrifis - Appareils maills pour les installations industrielles - Partie 5: Prsentation et caractrisation des dfauts (ISO 28721-5:2016) Emails und Emaillierungen - Emaillierte Apparate fr verfahrenstechnische Anlagen
6、- Teil 5: Darstellung und Charakterisierung von Fehlern (ISO 28721-5:2016) This European Standard was approved by CEN on 23 January 2016. CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this European Standard the status of a nationa
7、l standard without any alteration. Up-to-date lists and bibliographical references concerning such national standards may be obtained on application to the CEN-CENELEC Management Centre or to any CEN member. This European Standard exists in three official versions (English, French, German). A versio
8、n in any other language made by translation under the responsibility of a CEN member into its own language and notified to the CEN-CENELEC Management Centre has the same status as the official versions. CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Cze
9、ch Republic, Denmark, Estonia, Finland, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey andUnited Kingdom. EU
10、ROPEAN COMMITTEE FOR STANDARDIZATION COMIT EUROPEN DE NORMALISATION EUROPISCHES KOMITEE FR NORMUNG CEN-CENELEC Management Centre: Avenue Marnix 17, B-1000 Brussels 2016 CEN All rights of exploitation in any form and by any means reserved worldwide for CEN national Members. Ref. No. EN ISO 28721-5:20
11、16 EBS EN ISO 28721-5:2016EN ISO 28721-5:2016 (E) 3 European foreword This document (EN ISO 28721-5:2016) has been prepared by Technical Committee ISO/TC 107 “ Metallic and other inorganic coatings“ in collaboration with Technical Committee CEN/TC 262 “Metallic and other inorganic coatings” the secr
12、etariat of which is held by BSI. This European Standard shall be given the status of a national standard, either by publication of an identical text or by endorsement, at the latest by September 2016, and conflicting national standards shall be withdrawn at the latest by September 2016. Attention is
13、 drawn to the possibility that some of the elements of this document may be the subject of patent rights. CEN and/or CENELEC shall not be held responsible for identifying any or all such patent rights. According to the CEN-CENELEC Internal Regulations, the national standards organizations of the fol
14、lowing countries are bound to implement this European Standard: Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands,
15、 Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and the United Kingdom. Endorsement notice The text of ISO 28721-5:2016 has been approved by CEN as EN ISO 28721-5:2016 without any modification. BS EN ISO 28721-5:2016ISO 28721-5:2016(E)Foreword iv1 Scope . 1
16、2 Normative references 13 Terms and definitions . 14 Enamelling defects . 24.1 Colour lines 24.1.1 General 24.1.2 Strain lines . 24.1.3 Tearings . 34.1.4 Pearl lines . 44.1.5 Shore lines . 44.1.6 Drying cracks 54.2 Boiling defect 64.2.1 Further designations 64.2.2 Description 64.2.3 Origin and cause
17、s 74.2.4 Classification . 74.2.5 Suggestions for defect treatment . 74.3 Rough enamel surface . 74.3.1 Underfired areas 74.3.2 Eggshell 84.4 Dimple 94.4.1 Further designations 94.4.2 Description .104.4.3 Origin and causes .104.4.4 Classification 104.4.5 Suggestions for defect treatment 104.5 Pinhole
18、s 104.5.1 Further designations .104.5.2 Description .104.5.3 Origin and causes .114.5.4 Classification 114.5.5 Suggestions for defect treatment 114.6 Contamination 114.6.1 Chamotte/refractory clay 114.6.2 Scale .124.6.3 Ceramic fibres134.7 Colour deviations . 144.7.1 Water marks . 144.7.2 Colour sta
19、ins .155 Repaired areas .165.1 Polished area 165.1.1 Further designations .165.1.2 Description .165.1.3 Origin and causes .175.1.4 Classification 175.1.5 Suggestions for defect treatment 175.2 Enamel-covered area after grinding 175.2.1 Further designations .175.2.2 Description .175.2.3 Origin and ca
20、uses .185.2.4 Classification 185.2.5 Suggestions for defect treatment 18 ISO 2016 All rights reserved iiiContents PageBS EN ISO 28721-5:2016ISO 28721-5:2016(E)ForewordISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO member bodies).
21、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, governmental and non-g
22、overnmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.The procedures used to develop this document and those intended for its further maintenance are described
23、 in the ISO/IEC Directives, Part 1. In particular the different approval criteria needed for the different types of ISO documents should be noted. This document was drafted in accordance with the editorial rules of the ISO/IEC Directives, Part 2 (see www.iso.org/directives). Attention is drawn to th
24、e possibility that some of the elements of this document may be the subject of patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of any patent rights identified during the development of the document will be in the Introduction and/or on the ISO
25、list of patent declarations received (see www.iso.org/patents). Any trade name used in this document is information given for the convenience of users and does not constitute an endorsement.For an explanation on the meaning of ISO specific terms and expressions related to conformity assessment, as w
26、ell as information about ISOs adherence to the WTO principles in the Technical Barriers to Trade (TBT) see the following URL: Foreword - Supplementary informationThe committee responsible for this document is ISO/TC 107, Metallic and other inorganic coatings, and in collaboration with Technical Comm
27、ittee CEN/TC 262, Metallic and other inorganic coatings.ISO 28721 was prepared by the European Committee for Standardization (CEN) Technical Committee CEN/TC 262, Metallic and other inorganic coatings, in collaboration with ISO Technical Committee ISO/TC 107, Metallic and other inorganic coatings, i
28、n accordance with the Agreement on technical cooperation between ISO and CEN (Vienna Agreement).ISO 28721 consists of the following parts, under the general title Vitreous and porcelain enamels Glass-lined apparatus for process plants: Part 1: Quality requirements for apparatus, components, applianc
29、es and accessories Part 2: Designation and specification of resistance to chemical attack and thermal shock Part 3: Thermal shock resistance Part 4: Quality requirements for glass-lined flanged steel pipes and flanged steel fittings Part 5: Presentation and characterization of defectsiv ISO 2016 All
30、 rights reservedBS EN ISO 28721-5:2016INTERNATIONAL STANDARD ISO 28721-5:2016(E)Vitreous and porcelain enamels Glass-lined apparatus for process plants Part 5: Presentation and characterization of defects1 ScopeThis part of ISO 28721 establishes a system for the cataloguing of defects in enamellings
31、 for chemical service and vessels. In addition, it describes some types of areas in which defects have been treated and which can easily be confounded with enamelling defects. It serves for a consistent language use concerning the designation and characterization of enamelling defects.This part of I
32、SO 28721 is limited to detectable defects and does not purport to fully take into consideration all occurring types of defects. It does not evaluate enamelling defects; the classification carried out is based on experience and corresponds, as far as possible, to ISO 28721-1.NOTE Regarding the accept
33、ance of glass lined equipment for use in process engineering, ISO 28721-1 applies.2 Normative referencesThe following documents, in whole or in part, are normatively referenced in this document and are indispensable for its application. For dated references, only the edition cited applies. For undat
34、ed references, the latest edition of the referenced document (including any amendments) applies.ISO 28721-1, Vitreous and porcelain enamels Glass-lined apparatus for process plants Part 1: Quality requirements for apparatus, components, appliances and accessories3 Terms and definitionsFor the purpos
35、es of this document, the following terms and definitions apply.3.1enamelling defectdefect arising during the enamelling of equipment and pipelines to be used in process engineering3.2reparable enamelling defectenamelling defect that can be remedied without thermal post-treatmentEXAMPLE Defect that c
36、an be remedied by polishing.3.3non-reparable enamelling defectdefect in the enamel coating that renders a component unfit for its respective intended use3.4refiringfurther enamel firing (also local), with or without another application3.5re-enamellingcomplete new creation of the enamel coating ISO 2
37、016 All rights reserved 1BS EN ISO 28721-5:2016ISO 28721-5:2016(E)4 Enamelling defects4.1 Colour lines4.1.1 GeneralThe enamelling defects strain lines (4.1.2), tearings (4.1.3) and pearl lines (4.1.4) are closely related to one another. The causes of their development and their appearances are simil
38、ar.4.1.2 Strain lines4.1.2.1 Further designationsMerged strain lines, linearly upward fused ground coat and hairlines.4.1.2.2 DescriptionStrain lines are lines that are always dark and running parallel, or concentrically in the usually blue or white glass cover coat (see Figure 1). In a severe case
39、of strain lines, a number of bubbles or blisters in a single line can appear, forming a pearl line (4.1.4).a) White cover coat with macroscopically detectable strain linesb) Lateral view, white cover coat exploring leapt up dark ground coatFigure 1 Strain lines4.1.2.3 Origin and causesStrain lines a
40、rise during enamelling due to thermally or mechanically induced stress in the component. When heating up, the ground coat and the covering bisque cracks open. During firing, parts of the ground coat penetrate into the cover coat.Possible causes are the following: a wrong combination of steel/ground
41、coat/cover coat; weld seam made from non-suitable filler material; mixing zones in the weld metal; non-adapted temperature control during enamelling of constructively unfavourable components, e.g. components showing mass accumulation;2 ISO 2016 All rights reservedBS EN ISO 28721-5:2016ISO 28721-5:20
42、16(E) plastic deformation of the component during enamelling.4.1.2.4 ClassificationNon-reparable enamelling defect.4.1.2.5 Suggestions for defect treatmentRe-enamelling, taking into consideration the causes mentioned in 4.1.2.3.4.1.3 Tearings4.1.3.1 Further designationsHairlines.4.1.3.2 DescriptionT
43、earings are mostly dark lines, running parallel or concentrically in the cover coat, i.e. lines that are always dark in blue enamel and either dark or light and transparent in white enamel. In contradiction to pearl lines (see 4.1.4), the lines do not show large blisters and are closely related to s
44、train lines (see 4.1.2). Unlike strain lines, however, these lines are recessed (see Figure 2).Figure 2 Tearings4.1.3.3 Origin and causesTearings arise during enamelling due to thermally or mechanically induced stress in the component. When heating up, the enamel bisque and/or the enamel coating cra
45、ck(s) open. These cracks merge again during firing. If only the cover coat is affected, dark lines appear. If the crack runs through to the metal surface, blisters in the form of pearl lines also (see 4.1.4) arise along the crack (for causes, see 4.1.2.3).4.1.3.4 ClassificationNon-reparable enamelli
46、ng defect. As, without carrying out destructive testing, it cannot be determined whether parts of the ground coat leap up, toleration is generally not possible for safety reasons.4.1.3.5 Suggestions for defect treatmentRe-enamelling, taking into consideration the causes mentioned in 4.1.3.3. ISO 201
47、6 All rights reserved 3BS EN ISO 28721-5:2016ISO 28721-5:2016(E)4.1.4 Pearl lines4.1.4.1 Further designationsBubble lines and blister lines.4.1.4.2 DescriptionPearl lines are blisters lying behind each other in a line, often combined with strain lines (see 4.1.1) or tearings (see 4.1.2 and Figure 3)
48、.Figure 3 Pearl lines, i.e. series of blisters in line, in zones showing strain lines (see 4.1.2)4.1.4.3 Origin and causesPearl lines arise during enamelling due to thermally or mechanically induced restraints in the component. When heating up, the enamel bisque and the enamel coating crack open thr
49、ough to the steel. During firing, the metal oxidizes, a process accompanied by gas-forming reactions in the boundary layer. The lines run to form strain lines (see 4.1.2), along which blisters and pores are positioned as if on a string of beads (for causes, see 4.1.2.3).4.1.4.4 ClassificationNon-reparable defect.4.1.4.5 Suggestions for defect treatmentRe-enamelling, taking into consideration the causes mentioned in 4.1.4.3.4.1.5 Shore lines4.1.5.1 Further designationsNone.4.1.5.2 DescriptionShore lines are a group of parallel or nea
