BRITISH STANDARD BS EN 22401 1994 ISO 2401 1972 Covered electrodes — Determination of the efficiency, metal recovery and deposition coefficient The European Standard EN 22401 1994 has the status of a[.]
BRITISH STANDARD Covered electrodes — Determination of the efficiency, metal recovery and deposition coefficient The European Standard EN 22401:1994 has the status of a British Standard BS EN 22401:1994 ISO 2401:1972 BS EN 22401:1994 Cooperating organizations The European Committee for Standardization (CEN), under whose supervision this European Standard was prepared, comprises the national standards organizations of the following countries: Austria Belgium Denmark Finland France Germany Greece Iceland Ireland Italy Luxembourg Netherlands Norway Portugal Spain Sweden Switzerland United Kingdom This British Standard, having been prepared under the direction of the Welding Standards Policy Committee, was published under the authority of the Standards Board and comes into effect on 15 May 1994 © BSI 12-1999 The following BSI references relate to the work on this standard: Committee reference WEE/39 Draft announced in BSI News, May 1993 ISBN 580 22301 Oesterreichisches Normungsinstitut Institut belge de normalisation Dansk Standardiseringsraad Suomen Standardisoimisliito, r.y Association franỗaise de normalisation Deutsches Institut fỹr Normung e.V Hellenic Organization for Standardization Technological Institute of Iceland National Standards Authority of Ireland Ente Nazionale Italiano di Unificazione Inspection du Travail et des Mines Nederlands Normalisatie-instituut Norges Standardiseringsforbund Instituto Portuguès da Qualidade Asociación Espola de Normalización y Certificación Standardiseringskommissionen i Sverige Association suisse de normalisation British Standards Institution Amendments issued since publication Amd No Date Comments BS EN 22401:1994 Contents Cooperating organizations National foreword Foreword Scope and field of application Terms and definitions Test plates Procedure Calculation of efficiency and metal recovery Calculation of deposition coefficient National annex NA (informative) Committees responsible Figure © BSI 12-1999 Page Inside front cover ii 3 4 Inside back cover i BS EN 22401:1994 National foreword This British Standard has been prepared under the direction of the Welding Standards Policy Committee and is the English language version of EN 22401:1994 Covered electrodes — Determination of the efficiency, metal recovery and deposition coefficient, published by the European Committee for Electrotechnical Standardization (CEN) which endorses ISO 2401:1972 Covered electrodes — Determination of the efficiency, metal recovery and deposition coefficient published by the International Organization for Standardization (ISO) EN 22401:1993 was produced as a result of international discussion in which the UK took an active part A British Standard does not purport to include all the necessary provisions of a contract Users of British Standards are responsible for their correct application Compliance with a British Standard does not of itself confer immunity from legal obligations Summary of pages This document comprises a front cover, an inside front cover, pages i and ii, the EN title page, pages to 6, an inside back cover and a back cover This standard has been updated (see copyright date) and may have had amendments incorporated This will be indicated in the amendment table on the inside front cover ii © BSI 12-1999 EUROPEAN STANDARD EN 22401 NORME EUROPÉENNE February 1994 EUROPÄISCHE NORM UDC 621.791.7 Descriptors: Welding electrodes, covered electrodes, efficiency, steels English version Covered electrodes — Determination of the efficiency, metal recovery and deposition coefficient (ISO 2401:1972) Electrodes enrobées — Détermination des divers rendements et du coefficient de dépôt (ISO 2401:1972) Umhüllte Stabelektroden — Bestimmung der Ausbringung, der Abschmelzleistung und der Abschmelzkonstanten (ISO 2401:1972) This European Standard was approved by CEN on 1994-02-04 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 national standard without any alteration Up-to-date lists and bibliographical references concerning such national standards may be obtained on application to the Central Secretariat or to any CEN member This European Standard exists in three official versions (English, French, German) A version in any other language made by translation under the responsibility of a CEN member into its own language and notified to the Central Secretariat has the same status as the official versions CEN members are the national standards bodies of Austria, Belgium, Denmark, Finland, France, Germany, Greece, Iceland, Ireland, Italy, Luxembourg, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland and United Kingdom CEN European Committee for Standardization Comité Européen de Normalisation Europäisches Komitee für Normung Central Secretariat: rue de Stassart 36, B-1050 Brussels © 1994 Copyright reserved to CEN members Ref No EN 22401:1994 E EN 22401:1994 Foreword This draft European Standard based on the International Standard, Covered electrodes — Determination of the efficiency, metal recovery and deposition coefficient (ISO 2401:1972) submitted to the Unique Acceptance Procedure in accordance with Resolution BTS C48/1992 taken by BTS Engineering The result of the Unique Acceptance Procedure was positive 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 August 1994, and conflicting national standards shall be withdrawn at the latest by August 1994 In accordance with the CEN/CENELEC Internal Regulations, the following countries are bound to implement this European Standard: Austria, Belgium, Denmark, Finland, France, Germany, Greece, Iceland, Ireland, Italy, Luxembourg, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland and United Kingdom © BSI 12-1999 EN 22401:1994 Scope and field of application This International Standard specifies a method for the determination of the efficiency, weld metal recovery and deposition coefficient of carbon steel and low alloy high tensile steel covered electrodes in the sizes 3.15 to 6.3 mm1) For the practical use of this International Standard, the precision of measurement specified is sufficient because of the inherent variation in characteristics of individual electrodes Section specifies the measurement of a number of different values It is, however, necessary to measure only those values required for the calculation of the particular factors being determined Terms and definitions 2.1 nominal electrode efficiency, RN the ratio of the mass of weld metal deposited under standard conditions to the mass of nominal diameter core wire consumed for a given electrode 2.2 effective electrode efficiency, RE these suffixes shall be used as follows: DC positive RN + DC negative RN – AC RN * Test plates 3.1 Number For each diameter of electrode to be tested, one test plate shall be welded 3.2 Specification The test plate shall be of carbon steel (up to 0.25 % C) and shall have approximately the following dimensions: — width — length — thickness 75 mm 300 mm 12 mm In most cases a single test piece will be long enough; if this is not the case, a second test piece having a length of 150 mm or, if necessary, 300 mm shall be placed end to end with the first test piece (see Figure) the ratio of the mass of weld metal deposited under standard conditions to the actual mass of core wire consumed 2.3 overall weld metal recovery, RG the ratio of the mass of weld metal deposited under standard conditions to the total mass of a given electrode tested 2.4 deposition efficiency, RD the ratio of the mass of weld metal deposited under standard conditions to the total mass of a given electrode consumed, exclusive of stub ends 2.5 deposition coefficient, D the mass of weld metal deposited under standard conditions per ampere minute for a given electrode when reporting the results of tests, a further suffix shall be added to the above abbreviations RN, RE, RG, RD and D to indicate the type of current used to establish the values 1) Figure In order to facilitate weighing after welding, the test plate may, where two plates have been used, be broken into two parts The surface of the plate on which the deposit is to be made shall be cleaned, if necessary, by light grinding or other suitable means so that it is free from scale, rust, paint, oil, etc After cleaning and before welding, the plate shall be weighed with a precision of ± g The method described can be applied to other sizes of electrodes © BSI 12-1999 EN 22401:1994 Procedure 2) 4.1 Three or five electrodes of the diameter to be tested shall be used on the test plate Before welding, the electrodes shall be weighed to ± g The total mass of three or five electrodes is called mE The mass of three or five core wires, obtained by carefully removing the covering from another three or five electrodes of the same batch, is called mw The mass of three or five core wires mw can also be obtained by calculation after measuring the diameter and the total length Lw of the core wire of the electrodes to be tested, assuming the density of steel to be 7.85 g/cm3 4.2 The welding current I shall be equal to about 90 % of the maximum value of the range for the flat position indicated by the electrode manufacturer on the packet Its value shall be measured by means of a damped ammeter of Class precision for electrical measuring apparatus For AC, the root mean square (RMS) value of the current shall be measured The machine setting shall not be changed during the whole test For the calculation of the deposition coefficient, the average value Im of the root mean square values of the current measured during the test shall be used 4.3 The arc length and welding procedure shall be typical for the electrode being used and the deposited bead shall be free from major defects 4.4 Electrodes suitable for welding on DC only, or those for which the manufacturer specified that DC is preferable, shall be tested on DC with the polarity recommended by the manufacturer 4.5 Electrodes suitable for welding on either DC or AC shall be tested on alternating current and, in this case, the following provisions regarding the welding transformer are recommended: a) the transformer should have an open circuit voltage not more than 10 V higher than the minimum value indicated by the electrode marking; b) for the setting used for welding, the current waveform supplied by the transformer in short-circuit conditions should have a form factor F3) included within the following limits: 1.11 < F < 1.2 4.6 Each electrode shall be deposited in the flat position and used without interruption until a stub length of 50 mm remains (It is recommended that the required length of stub end be marked on the electrode before starting to weld.) 4.7 The arcing time of each electrode shall be measured with a precision of ± 0.2 s, and the total time t for the three or five electrodes calculated in minutes 4.8 After each run, the test plate may be cooled in water, but the test plate shall be dry before welding is resumed The slag and spatter adhering to the test plate shall be carefully removed before depositing subsequent runs The interpass temperature shall not exceed 100 °C 4.9 After welding each run, the stub ends shall be retained, avoiding any loss of unfused covering, and, when cooled down, the three or five stub ends can be 1) weighed with a precision of ± g and their total mass ms determined; 2) weighed after careful removal of all the remaining covering and their total mass mws determined; 3) measured for the length of the core wire (to ± mm) to determine the measured total length of the stub ends Ls 4.10 After completion of welding, the test plate shall be cooled to room temperature and, after removal of any slag and spatter adhering to the test plate (and also after drying if water cooling has been applied), it shall be weighed with a precision of ± g The total mass of the deposit mD can be determined from the difference with the original mass of the plate as found in 4.1 4.11 The total length of stub ends shall be between 240 and 260 mm for five electrodes and between 144 and 156 mm for three electrodes If the total stub end length is outside these limits, the test shall be repeated Calculation of efficiency and metal recovery 5.1 The total nominal mass of the consumed lengths of the core wire of the three or five electrodes mCN shall be calculated, taking as a basis the nominal diameter and the nominal length less the measured length (to ± mm) of core wire in the three or five stub ends (Ls) The density of steel is assumed to be 7.85 g/cm3 2) If the mass of the deposit from each electrode is more than 100 g, it is permissible to use only three electrodes 3) For an alternating current, the “form factor” F is the ratio of its RMS value to its mean value The limits given above correspond to those observed on common welding transformers in short-circuit conditions The form factor F can be determined either by oscillographic recording or using simultaneously two ammeters in series, one having a scale in RMS values of the current and not very sensitive to the wave shape (for example, ferromagnetic or thermal type), the other having a scale in mean values of the current (for example, magneto-electric with rectifier type) © BSI 12-1999 EN 22401:1994 5.2 The total effective mass of the consumed length of the core wire of the three or five electrodes mCE is given by the formula LS m CE = m W – - L W where mw is the total mass of the core wires; Ls is the measured total length of the stub ends; Lw is the measured total length of the core wires; or, alternatively, by the formula mCE = mw – mws where mws is the total mass of the core wires in the stub ends 5.3 The nominal electrode efficiency is given by the ratio mD × 100 R N % = -m CN where mD is the mass of deposited weld metal; mCN is the nominal mass of consumed core wire 5.4 The effective electrode efficiency is given by the ratio 5.6 The deposition efficiency is given by the ratio mD - × 100 R D % = -mE – mS where ms is the total mass of the stub ends The values of the efficiencies and recoveries calculated according to 5.3 to 5.6 shall be expressed as rounded whole numbers, i.e without decimals (for example, 93.4 % would become 93 %, 93.5 % would become 94 %) Calculation of deposition coefficient The deposition coefficient, expressed in grams per ampere minute, is given by the ratio mD D = -Im × t where mD is the mass of deposited metal, in grams; Im is the welding current, in amperes; t is the arcing time, in minutes The values calculated as above shall be expressed with two places of decimals [for example, 0.16 g/(A·min) for 0.164 g/(A·min) and 0.17 g/(A·min) for 0.165 g/(A·min)] mD R E % = - × 100 m CE 5.5 The overall weld metal recovery is given by the ratio mD R G % = × 100 mE where mE is the total mass of electrodes tested © BSI 12-1999 blank BS EN 22401:1994 National annex NA (informative) Committees responsible The United Kingdom participation in the preparation of this European Standard was entrusted by the Welding Standards Policy Committee (WEE/-) to Technical Committee WEE/39 upon which the following bodies were represented: Aluminium Federation Associated Offices Technical Committee Association of Welding Distributors British Association for Brazing and Soldering British Compressed Gases Association British Constructional Steelwork Association Ltd British Steel Industry Electricity Association Engineering Equipment and Materials Users’ Association Lloyds Register of Shipping Magnesium Industry Council Power Generation Contractors’ Association (BEAMA Ltd.) Process Plant Association Stainless Steel Wire Industry Association Welding Institute Welding Manufacturers’ Association (BEAMA Ltd.) 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