www bzfxw com BRITISH STANDARD BS EN 874 1995 Gas welding equipment — Oxygen/fuel gas blowpipes (cutting machine type) of cylindrical barrel — Type of construction, general specifications, test method[.]
BRITISH STANDARD Gas welding equipment — Oxygen/fuel gas blowpipes (cutting machine type) of cylindrical barrel — Type of construction, general specifications, test methods The European Standard EN 874:1995 has the status of a British Standard ICS 25.160.30 BS EN 874:1995 BS EN 874:1995 Committees responsible for this British Standard The preparation of this British Standard was entrusted to Technical Committee WEE/18, Gas welding and cutting appliances, upon which the following bodies were represented: British Compressed Gases Association British Railways Board Consumer Policy Committee of BSI Department of Trade and Industry (Consumer Safety Unit, CA Division) Health and Safety Executive LP Gas Association Railway Industry Association South Bank University Welding Manufacturers’ Association (BEAMA Ltd.) This British Standard, having been prepared under the direction of the Engineering Sector Board, was published under the authority of the Standards Board and comes into effect on 15 December 1995 © BSI 10-1999 The following BSI references relate to the work on this standard: Committee reference WEE/18 Draft for comment 92/83315 DC ISBN 580 24678 Amendments issued since publication Amd No Date Comments BS EN 874:1995 Contents Committees responsible National foreword Foreword Text of EN 874:1995 List of references © BSI 10-1999 Page Inside front cover ii Inside back cover i BS EN 874:1995 National foreword This British Standard has been prepared by Technical Committee WEE/18 and is the English language version of EN 874:1995 Gas welding equipment — Oxygen/fuel gas blowpipes (cutting machine type) of cylindrical barrel — Type of construction, general specifications, test methods, published by the European Committee for Standardization (CEN) EN 874:1995 was produced as a result of international discussion in which the UK took an active part Cross-references Publication referred to Corresponding British Standard EN 29090:1992 BS EN 29090:1992 Specification for gas tightness of equipment for gas welding and allied processes EN 29539:1992 BS EN 29539:1992 Specification for materials for equipment used in gas welding, cutting and allied processes ISO 3:1973 BS 2045:1965 Preferred numbers 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 20, 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 10-1999 EUROPEAN STANDARD EN 874 NORME EUROPÉENNE April 1995 EUROPÄISCHE NORM ICS 25.160.30 Descriptors: Welding equipment, oxygen cutting, oxyacetylene cutting, blowpipes, dimensions, safety, performance evaluation, testing conditions, tests English version Gas welding equipment — Oxygen/fuel gas blowpipes (cutting machine type) of cylindrical barrel — Type of construction, general specifications, test methods Matériel de soudage aux gaz — Chalumeaux oxy-gaz combustible (type machine d’oxycoupage) corps cylindrique — Type de construction, spécifications générales, méthodes d’essai Gasschweißgeräte — Maschinenschneidbrenner mit zylindrischen Schaft für Brenngas/Sauerstoff — Bauarten, allgemeine Anforderungen, Prüfverfahren ｗｗｗ．ｂｚｆｘｗ．ｃｏｍ This European Standard was approved by CEN on 1995-01-09 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 © 1995 All rights of reproduction and communication in any form and by any means reserved in all countries to CEN and its members Ref No EN 874:1995 E EN 874:1995 Foreword Page This European Standard has been prepared by the Technical Committee CEN/TC 121, Welding, of which the secretariat is held by DS 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 October 1995, and conflicting national standards shall be withdrawn at the latest by October 1995 According to 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 Contents Foreword Scope Normative references Terminology Definitions Dimensions Hose connections Material Marking Safety and operational requirements 10 Test conditions 11 Instructions for use Annex A (informative) Cutting nozzles seats and fixing Annex B (informative) Terminology, example of construction Figure — Fuel gas induction mixer (low and high pressure) Figure — Mixer without injector action Figure — Main specifications Figure — Fuel gas injector mixer Figure — Mixer without injector action Figure — Fuel gas injector mixer with backflow resistance in accordance with 9.1.5 Figure — Overheating test Figure — Acceptance requirements Figure — Assembly for closing flat nozzle end faces Page 3 3 5 6 15 Figure 10 — Segment shape of copper plate, dimensions Figure 11 — Assembly for closing nozzle end faces that are not flat Figure 12 — Assembly for testing the resistance against backflow of heating oxygen in the fuel gas line Figure 13 — Assembly for testing the resistance against backflow of fuel gas in the heating oxygen line Figure B.1 — Blowpipe with built-in valves Figure B.2 — Blowpipe with screw-on valve Figure B.3 — Two-hose blowpipe Figure B.4 — Heating and cutting nozzle with mixing point in the blowpipe Figure B.5 — Gas mixing nozzle with mixing in the nozzle Figure B.6 — Heating and cutting nozzle with mixing point in the blowpipe Table — Dimensions of the rack Table — Designation and symbols of the gases Table — Test conditions Table B.1 — List of terms 11 13 14 15 16 16 17 17 18 18 ｗｗｗ．ｂｚｆｘｗ．ｃｏｍ 19 16 16 4 6 10 © BSI 10-1999 EN 874:1995 Scope Definitions This standard is applicable to machine cutting blowpipes with cylindrical barrels where the nozzle centre is coaxial with the barrel, operating with oxygen and fuel gas, with a cutting range from mm to 300 mm cutting thickness, and which are fitted to a gas cutting machine This standard specifies the characteristics of machine cutting blowpipes and gives specifications and corresponding tests For the purposes of this standard, the following definitions apply Normative references This European Standard incorporates by dated or undated reference, provisions from other publications These normative references are cited at the appropriate places in the text and the publications are listed hereafter For dated references, subsequent amendments to or revisions of any of these publications apply to this European Standard only when incorporated in it by amendment or revision For undated references the latest edition of the publication referred to applies EN 560, Gas welding equipment — Hose connections for equipment for welding, cutting and allied processes EN 730, Gas welding equipment — Equipment used in gas welding, cutting and allied processes — Safety devices for fuel gases and oxygen or compressed air — General specifications, requirements and tests EN 29090 (ISO 9090:1989), Gas tightness of equipment for gas welding and allied processes EN 29539 (ISO 9593:1988), Material requirements for equipment used in gas welding, cutting and allied processes ISO 3:1973, Preferred numbers — Series of preferred numbers 4.1 Common types of mixing systems 4.1.1 injector-mixer mixing system in which the fuel gas and the oxidizing gas are mixed by the action of the latter which, being discharged from the orifice of the injector, reduces the pressure, thus entraining the fuel gas Accordingly, when the valve in the fuel gas channel is closed while the oxidizing gas is normally discharged, the pressure in this channel is below the atmospheric pressure If during the same time the fuel gas hose connecting nipple is exposed to the atmosphere, air will be entrained (fuel gas valve open) (see Figure 1) 4.1.2 mixer without injector action mixing system in which the fuel gas and the oxidizing gas are mixed when the latter is discharged from the orifice and meets the fuel gas which is discharged at nearly identical pressure When the valve in the fuel gas channel is closed while the oxidizing gas is discharged, the pressure in this channel is higher than the atmospheric pressure If during the same time the fuel gas hose connecting nipple is exposed to the atmosphere, oxidizing gas will be discharged (fuel gas valve open) (see Figure 2) ｗｗｗ．ｂｚｆｘｗ．ｃｏｍ Terminology Terminology concerning machine cutting blowpipes is given in Annex B The design details of the blowpipes are left to the discretion of the manufacturer; the illustrations in the standard are solely to clarify the terms 4.2 High pressure and low pressure blowpipes 4.2.1 high pressure blowpipe a blowpipe in which the pressure of both the fuel gas and the oxidizing gas measured immediately before the point of mixing is higher than the pressure of the gas mixture measured downstream between mixer and nozzle (see Figure 2) 4.2.2 low pressure blowpipe a blowpipe in which the fuel gas pressure measured immediately before the point of mixing is lower than the pressure of the gas mixture measured down-stream between mixer and nozzle (see Figure 1) 4.3 Blowpipes classified according to the possibility of varying the flow rate 4.3.1 Blowpipes with multiple flow rates A blowpipe giving a range of flow rates corresponding to a series of nozzles © BSI 10-1999 EN 874:1995 4.3.1.1 blowpipes with multiple flow rates adjusted by means of the injector 4.3.1.3 blowpipe with multiple flow rates adjusted by means of gas control valves a blowpipe with multiple flow rates which are varied by means of a device for adjustment of the injector cross-section (blowpipe with variable injector) a blowpipe with multiple flow rates which are varied by adjustment of the adjustment valves 4.3.1.2 blowpipe with multiple flow rates adjusted by the pressure a blowpipe with multiple flow rates which are varied by adjusting the feed pressures (blowpipe with fixed mixer) ｗｗｗ．ｂｚｆｘｗ．ｃｏｍ Figure — Fuel gas induction mixer (low and high pressure) NOTE Position of the mixing systems The mixing systems in accordance with 4.1.1 and 4.1.2 are usually in the blowpipe or in the nozzle pf > pm po > p m Figure — Mixer without injector action © BSI 10-1999 EN 874:1995 4.4 Blowpipes classified according to the mixing position 4.4.1 blowpipes with preliminary mixer the mixture of heating oxygen and fuel gas is ensured by the injector-mixer located before the cutting nozzle 4.4.2 blowpipes with nozzle mixing The shank length (L) is the length on which the blowpipe holder can be fixed The shank length will be preferably equal to 50 mm, 100 mm, 160 mm, 250 mm, and 400 mm If other lengths are to be used, they should comply with the series R 20 (ISO 3) 5.3 Rack the heating oxygen and fuel gas ways are independent in the blowpipe and the head The gases are mixed in the cutting nozzle (nozzle mixing) 4.5 Backfire, sustained backfire, flashback, backflow 4.5.1 backfire the return of the flame into the blowpipe with a popping sound, the flame being either extinguished or reignited at the nozzle 4.5.2 sustained backfire 5.2 Shank length The rack is not mandatory, unless required by the blowpipe fixing and height adjusting device If a rack is fitted it shall comply either with type F or S, given in Table Table — Dimensions of the rack Spur tooth rack Type F Type S Module 1,25 Pitch in mm 3,14 3,927 Width B in mm –0,2 –0,2 Dimension E in mm D + –0,3 D + –0,3 ｗｗｗ．ｂｚｆｘｗ．ｃｏｍ the return of the flame into the blowpipe with continued burning within the neck or mixer (This may be accompanied by an initial popping sound followed by a continuous hissing sound from the continued burning within the blowpipe.) A spur tooth rack is characterized by its width, the module and pitch of its teeth, its position on the cylinder shank (dimension E in Figure 3) 4.5.3 flashback the return of the flame through the blowpipe into the hoses and even the regulators It may also reach the acetylene cylinder, causing heating and decomposition of the contents 4.5.4 backflow flowing back of the gas with the higher pressure into the hose of the gas with the lower pressure This can be caused by the nozzle exit becoming blocked or restricted Figure — Main specifications Dimensions 5.1 Shank diameter The diameter of the blowpipe cylinder shank (D) is preferably equal to one of the following values: 32 mm = usual diameter; 28 mm = useful diameter for portable machines and robot equipment; 45 mm = used e.g for automatic internal ignition systems; Tolerance of shank diameter mm –0,2 © BSI 10-1999 Hose connections The nipples shall be either permanently fitted to the shank or detachable The external profile of the nipples is left to the choice of manufacturer Where a threaded union connection is used it shall conform to EN 560 Material The material requirements, according to EN 29539, shall be fulfilled EN 874:1995 Components in contact with oxygen shall be free from oil, grease and other contaminants Marking The marking shall be legible and durable 8.1 Marking of the blowpipe The blowpipe shank shall carry the name or registered trade mark of the manufacturer (the term “manufacturer” includes distributors, suppliers or importers) and the reference number of this Standard The marking shall be in accordance with 8.5 and 8.6 The connection adjacent to the oxygen inlet of blowpipes with fixed hose connecting nipples shall be identified by the letter “O” 8.2 Marking of oxygen valves The heating oxygen valves (body or knob) shall be identified by the letter “O” and/or the colour blue The cutting oxygen valve shall be identified if similarly designed 8.3 Marking of nozzles All nozzles shall be marked with the name, registered trade mark or identifying mark of the manufacturer, with the symbol identifying the fuel gas and with a code to permit easy reference to the manufacturer’s operating data 8.4 Marking of interchangeable components Where mismatching of interchangeable components (e.g mixer and injector) could occur, an identifying code, the manufacturer’s trade mark and the symbol identifying the fuel gas shall be marked and shown in the operating data Figure — Fuel gas injector mixer with backflow resistance in accordance with 9.1.5 8.6 Gases to be used, symbols of gases The following gases may be used Where the full name of the gas cannot be imprinted the following symbols shall be used (see Table 2) Table — Designation and symbols of the gases Designation Oxygen Acetylene Propane, Butane or LPG (Liquefied Petroleum Gas) Natural gas, Methane Hydrogen MPS (methylacetylene-propadiene mixtures) and other fuel gas mixtures Coal gas Symbol O A P M H Y C ｗｗｗ．ｂｚｆｘｗ．ｃｏｍ For blowpipes, nozzles and interchangeable components capable of use with more than one fuel gas the abbreviation F shall be used Operating data shall give details of fuel gases for which these components are suitable Safety and operational requirements 8.5 Marking of mixers 9.1 Safety requirements The user is advised to refer to the operating instructions provided by the manufacturer (see clause 11) If operating pressures are marked on any part of the blowpipe they shall be indicated in bar If the mixing device is symbolically marked, indicating the blowpipe type, the marking should conform to the following symbols (see Figure 4, Figure and Figure 6) The blowpipe shall comply with the requirements of EN 29090 when tested in accordance with the methods specified in it The test, according to EN 29090, shall be carried out on new blowpipes and after the valve endurance test in 10.3; after the sustained backfire tests and the overheating tests according to 10.2.1 9.1.1 Gas tightness 9.1.2 Strength requirements The blowpipes shall be robust and suitable for the purpose intended They shall be able to resist maltreatment due to incorrect operation and handling, e.g backfire and shock Figure — Fuel gas injector mixer 9.1.3 Valve design Each gas line shall be separately closed with valve Valve elements shall remain captive in all positions Figure — Mixer without injector action © BSI 10-1999 EN 874:1995 H is the length of neutral flame inner cones X = H + + d2/2 (d2, see Figure 10) Figure — Overheating test 10.2.2.1.1 Test conditions Case No The blowpipe shall be fitted with a nozzle from the manufacturer’s range Tests at two pressure conditions shall be carried out for each nozzle in accordance with case or case given below and in Table A neutral flame shall be adjusted for each test at the nominal flow rates specified in the manufacturer’s operating data The position of the heating oxygen valve of the blowpipe shall be marked It shall not be modified afterwards If necessary, adjustment of the neutral flame shall be maintained by means of the fuel gas valve only Table — Test conditions Case Test no 2 Case No The manufacturer specifies a range of pressures for any one or both gases First test shall be made with the higher oxygen and fuel gas pressures Second test shall be made with the lower oxygen and fuel gas pressures The manufacturer only specifies one oxygen pressure and only one fuel gas pressure First test shall be made with oxygen pressure + 15 % and fuel gas pressure + 15 % Second test shall be made with oxygen pressure – 15 % and fuel gas pressure – 15 % Pressure Poxa max + 15 % – 15 % Pcb max + 15 % – 15 % a Pox is the oxygen pressure specified in manufacturer’s operating data (bar) b pc is the fuel gas pressure specified in manufacturer’s operation data (bar) © BSI 10-1999 EN 874:1995 Figure — Acceptance requirements 10.2.2.1.2 Procedure The nozzle axis shall be vertical The plane of the upper surface of the test segment shall be horizontal The heating flame shall be ignited, stabilized in the atmosphere at the adjustment level selected for the test, for a minimum duration of 30 s Tests shall be carried out with only the heating flame The cutting oxygen circuit shall be closed by means of the valve or closing device The heating flame shall always be maintained neutral The flat front end of the nozzle is brought in sliding contact with the surface of a conventional test segment, so that the heating orifices are completely closed five (5) times and in between four (4) times partially closed The test shall include five series of complete orifice closures (i.e × = 25) and partial orifice closures (i.e × = 20) within one minute The test segment shall pass five times in under the nozzle for one test Each time the nozzle passes on the test segment, it shall then remain in the atmosphere for a duration 11 times longer © BSI 10-1999 In the case of an unsuccessful test the blowpipe and nozzle shall be cooled and cleaned Two consecutive identical tests shall necessarily be acceptable (twice five passages of the test segment under the ignited nozzle) The vertical contact pressure between the copper plate and the nozzle shall be F = N Rotational frequency of the copper plate: n = min–1 Test radius: r = 165 mm The test assembly is shown in Figure The test segment shape can be either a circle sector or a rectangle Dimensions refer to diameter d2 circumscribed to heating orifices (see Figure 10) The test segment profile is defined in the vertical plane including the nozzle axis EN 874:1995 Figure — Assembly for closing flat nozzle end faces 10 © BSI 10-1999 EN 874:1995 Figure 10a — Longitudinal section along nozzle axis Figure 10b — Test segment shape Figure 10 — Segment shape of copper plate, dimensions (continued) © BSI 10-1999 11 EN 874:1995 Figure 10c — Front end of nozzle a = k1d2, k1 = 0,7 ± 0,1 l = k2d2, k2 = 1,5 ± 0,25 h = mm (+ 0,5; 0) 1/3 a k ak 1/2 a partial closures total closures Figure 10 — Segment shape of copper plate, dimensions (concluded) 10.2.2.1.3 Assessment 10.2.2.2.2 Procedure During the tests backfires shall occur The heating flame shall be reignited naturally or by the adjacent secondary flame during partial orifice closing, between contacts with the test segment and at the end of the test The backfire or backfires shall not cause sustained backfire Ignite the flame, adjust to neutral flame conditions, readjust if appropriate, first setting of the blowpipe on the copper plate after 30 s, no readjustment of the flame during the test; reignite immediately if flame extinguishes 10.2.2.2 Blowpipes with nozzle end face that is not flat The test shall be considered passed if no sustained backfire occurs in the course of the 25 cycles The test shall also be considered passed if after at least 10 cycles at least 30 backfires have occurred without sustained backfire If sustained backfire occurs the test is to be interrupted The nozzle and blowpipe are to be cooled and cleaned In this case the blowpipe shall complete the test twice without sustained backfire in order to pass the test Nozzle and blowpipe are to be cooled between the two retests each consisting of 25 cycles The test assembly is shown in Figure 11 10.2.2.2.1 Test conditions The end face of the nozzle shall be maintained parallel to the surface of a recessed copper plate on which it is intermittently placed The recess in the copper plate shall be matched to the nozzle shape under test The vertical contact pressure between the copper plate and the nozzle shall be F = N The nozzle shall be set on the test plate five times within five seconds The ratio of closing time to opening time shall be 1,00 : 1,25 A pause of 10 s shall follow in which the blowpipe shall not be set on the plate so that the blowpipe can once again be placed on the test plate five times within s in the ratio of closing to opening times stated The blowpipe shall be set in position × = 25 times in the rhythm described 12 10.2.2.2.3 Assessment 10.3 Valves endurance test The valves shall be subjected to a life cycle test of 000 openings and closings The closing torque used shall be the one given by the manufacturer After this endurance test, a leak test (see 10.1) shall be carried out © BSI 10-1999 EN 874:1995 10.4 Backflow test For mixers with marking as Figure The resistance against backflow is tested separately for both oxygen and fuel gas lines The tests are carried out with oil-free compressed air or with nitrogen for all nozzle sizes 10.4.1 Testing of resistance against backflow of oxygen in the fuel gas line 10.4.1.1 Test conditions Test conditions and the arrangement are shown in Figure 12 10.4.1.2 Procedure The blowpipe shall be tested using the following procedure: — heating oxygen and fuel gas valve fully open; — cutting oxygen valve closed; — adjust pressure on the oxygen side to twice the value of the highest pressure given by the manufacturer for the nozzle size being tested; — record the pressure on the pressure gauge at the fuel gas side 10.4.1.3 Assessment If the recorded pressure is lower than 0,5 times the lowest pressure of fuel gas given by the manufacturer for the particular nozzle size, then the requirement for resistance against backflow of oxygen is met 10.4.2 Testing of resistance against backflow of fuel gas in oxygen line 10.4.2.1 Test conditions Test conditions and the arrangement are shown in Figure 13 Figure 11 — Assembly for closing nozzle end faces that are not flat © BSI 10-1999 13 EN 874:1995 Figure 12 — Assembly for testing the resistance against backflow of heating oxygen in the fuel gas line 14 © BSI 10-1999 EN 874:1995 Figure 13 — Assembly for testing the resistance against backflow of fuel gas in the heating oxygen line 10.4.2.2 Procedure 11 Instructions for use The blowpipe shall be tested using the following procedure: — heating oxygen and fuel gas valve fully open; — cutting oxygen valve closed; — adjust pressure on the fuel gas side to twice the value of the highest pressure given by the manufacturer for the nozzle size being tested (for acetylene max test pressure 1,5 bar); — record the pressure on the pressure gauge at the oxygen side The appliance shall be accompanied by instructions in the national language of the country where it is sold The instructions shall include at least the following aspects: a) permissible type of gas; b) pressure and flow data; c) explanation of the markings and of the mixing principle; d) use of the necessary safety devices; e) safety requirements; f) measure before putting into service; g) putting into service; h) behaviour in the case of defects; i) stopping of operation; j) service, maintenance and repair 10.4.2.3 Assessment If the recorded pressure is lower than 0,5 times the lowest pressure of oxygen given by the manufacturer for the particular nozzle size, then the requirement for resistance against backflow of fuel gas is met © BSI 10-1999 15 EN 874:1995 Annex A (informative) Cutting nozzles seats and fixing The angle used for taper seats is not standardized The most common angles in use are: a) 30 0ẵ 0ắ and b) 30 3ẵ 15ắ Users should refer to operating instructions and ensure nozzle seat angle is compatible with blowpipe head before use Mismatching of angles can lead to seat leakage and nozzle backfire Annex B (informative) Terminology, example of construction Figure B.2 — Blowpipe with screw-on valve Figure B.1 — Blowpipe with built-in valves 16 © BSI 10-1999