1、STDOBSI BS EN 746-4-ENGL 2000 Lb24bb9 0841844 3T2 W BRITISH STANDARD Industrial thermoprocessing equipment - Part 4: Particular safety requirements for hot dip galvanizing thermoprocessing equipment The European Standard EN 74642000 has the status of a British Standard ICs 25.180.10 BS EN 74642000 l
2、 NO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMI“ED BY COPYRIGI LAW STD-BSI ES EN 74h-lr-ENGL 2000 Lb24bh9 0841845 237 been prepared under the dinxtion of the Engineering AmdNo. Date Sector Committee, was published under the authority of the Standards Committee and comes into effect on 15 Apni Zoo
3、0 0 BSI 04-2000 ISBN O 580 35978 6 BS EN 746-4:2000 comments National foreword This British Standard is the official English iiuiguage version of EN 74M2000. The UK participation in its preparation was entrusted by Technical Committee MCE/3, Safeguarding of machinery, to Subcommittee MCE/3/8, Thenno
4、processing equipment - Safety, which has the responsibility to: - aid enquirem to unde-d the text; - present to the respomible European committee any enquines on the - monitor related internaonai and European developments and promulgate interpretation, or proposals for change, and keep the UK intere
5、sts inform - heating systems; - cooling systems; - environmental control systems; - electrical and control systems. 3.1.2 Kettle Container for the galvanizing material. 3.1.3 Double Dipping Process whereby the component is immersed twice into the bath. 3.2 Components 3.2.1 Batch urocess Discrete wor
6、kpieces which are immersed in the zinc/zinc alloy. 3.2.2 Diu process Wire, strip or similar continuous material which is processed through the zinclzinc alloy bath. 4 LIST OF HAZARDS An assessment of the foreseeable risks arising from the use of the industrial thermoprocessing equipment has been car
7、ried out when this standard was elaborated. The clause has been condensed into a table (see Table 1). It summarizes those areas which require consideration by the manufacturer. For ease of reference the table indicates the need for safety features or instructions in columns. The table shall only be
8、used in conjunction with clauses 5 and 7 where further detail is given. Table 1 shows the hazard, hazardous situation and preventative measures and verification means identified for the equipment type described in this part to this standard. OBSI 04-2000 1 tem - 2 Hazard .I - .2 3 4 5 Hazardous situ
9、ations Preventative measures References ! !. 1 - 1 STDoBSI BS EN 7Yb-4-ENGL 2000 W 3b24bb9 0843852 479 I means*) Page 7 EN 746-42000 :rushing! ihearing Table 1: List of hazards, hazardous situations and preventative measures Accidental descent of the charging equipment 6 Verifi- ca tion Breakage of
10、lifting chain, rope or auxiliary equipment hermal Accidential introduction or accidental spillage of liquids in or onto the liquid bath Ejection of molten metal from evolution of steam or gases 1 Provide safety device) for interrupting the movement of the charging equipment when failure of the equip
11、ment occurs 2 Provide a device on the rope that prevents the rope loosening 3 Any manual control in use shall be designed to override any linked automatic control 1 Provide suitable screens 2 Appropriate slinging methods fie instruction handbook ;hould include the following juggestions: I Personal P
12、rotection Equipment provision 2 Correct fire extinguishers 3 Provision of warning signs When the process requires it, measures can include: 1 Operation systems to include drying of components 2 Training of operators EN 746- 1 : 1997, 5.2.2 EN 60204- 1 EN 292-2:1991, 3.7.8 d) + e) EN 746-42000, 5.2 p
13、rEN 1248:1998, Part 3 7.2.1 (d) 5.2 7.2.5 5.2 7.2.2 7.2.3 (a) 7.2.1 7.1 7.1 ( 1 and2 1 1 1 1 1 1 1 1 1 Nntinued *) see Note to clause 6 for explanation of numbers OBSI 04-2000 STD-BSI BS EN 74b-4-ENGL 2000 Lb24bb 0843853 305 Page 8 EN 746-42000 Table 1: (continued) 2 Hazard 3 Hazardous situations Ac
14、cidential introduction of gases into the bath by liquid or dragged into the bath by components. Ejection of molten metal from bati Overflow or spillage of molten metal Losses due to leakage of molten zinc through breakage of bath container Falling into molten metal 4 Preventative measures The instru
15、ction handbook should include the following suggestions: 1 Component design 2 Training of operators 3 Personal Protection Equipment provi Sion 4 Correct fire extinguishers The instruction handbook should include the following suggestions: 1 Training of personnel 2 Personal Protective Equipment provi
16、sion 3 Maintenanceihousekeeping 4 Observation of level and volume of component to be charged Instruction handbook: 1 Maintenancehousekeeping 2 Regular check of bath for condition 3 Where necessary provide protection with barriers or screens 1 Design, particularly charging area (e.g. barriers, safe g
17、uards) 2 Provision of warning signs he instruction handbook should include the following suggestions: Personal Protection Equipment 1e.g. non-slip footwear) 5 References 5.2 7.1 7.1 7.2.2 7.2.3 (a) 5.3 7.1 7.2.2 7.2.4 7.1 5.3 7.2.4 Table 2 7.2.1 5.6 7.2.1 7.2.2 6 Verifi- cation means 1 1 1 1 1 I I l
18、 l 1 and 2 (continued) OBSI 04-2000 STD-BSI BS EN 746-4-ENGL 2000 = 1624664 0841854 241 I inhalation of fumes - 1 tem - .6 1 Design Page 9 EN 746-4:2000 Table 1: (concluded) 2 Hazard 3 Hazardous situations Breakage of protection tube(s) of thermocouple(s) internal andor external Zinc andor zinc allo
19、y overheats Reaction between the material of the kettle and the molten zinc or zinc alloy leading to leakage Materials and Substances 4 Preventative measures Design to ensure fail safe conditions prevail or provide automatic shut down devices The instruction handbook should include the following sug
20、gestions: 1 Training of operators 2 Maintenancehouskeeping 2 Provide an effective ventilation system 3 Personal Protective Equipment provision 4 Maintenancehousekeeping 5 Training of personnel Neglecting ergonomic principles Unhealthy posture or excessive efforts causing impaired judgement or poor v
21、isibility during charging or discharging The equipment shall be designed in such a way that there is no hindrance to technical aids and possiblility for good working postures 5 References 5.4 7.1 7.2.4 5.5 5.5 7.2.2 7.2.4 7.1 6 Verifi- cation means 1 1 1 1 land2 1 1 1 OBSI 04-2000 STD-BSI BS EN 746-
22、4-ENGL 2000 W 1b24bb9 0841855 188 = Page 10 EN 746-4:2000 5 SAFETY REQUIREMENTS AND/OR MEASURES 5.1 General The manufacturer of hot dip galvanizing thermoprocessing equipment shall be required to meet the conditions detailed in this part to this standard. See EN 746-1 and EN 746-2 for general safety
23、 requirements relating to thennoprocessing equipment. Machinery shall comply with the provisions of this clause. They also shall comply with EN 292 for hazards which are relevant but not significant and which are not covered by this standard. In addition equipment shall comply as appropriate, with o
24、ther relevant parts of this standard listed in clause 2 as well as with EN 292 for hazards which are not covered in these standards. For requirements relating to signs and warning labels refer to EN 613 10-1 for frther information. NOTE: The following preventative measures have been detailed to show
25、 how the hazards and hazardous situations detailed in Table 1 can be minimized. An explanation of the hazard is given at the beginning followed by an explanation of the preventative measure(s). The general references to design in Table 1 to this standard are intended to draw attention to the need to
26、 consider design in this area. More detailed consideration of this matter is given in the sections which follow this general clause. 5.2 Uncontrolled immersion or spillage of liquids into or onto the molten metal If liquids impinge upon or are immersed in molten metal then rapid conversion to the ga
27、seous or superheat state occur, causing pressure build up and the consequent explosion or eruption of molten hot metal. When the galvanizing kettle is not fitted with an enclosure then for protection against ejected metal screens shall be provided, behind which persons could stay during immersion of
28、 workpieces into the baths. The screens shall give whole body protection. (1) NOTE: At the present time, no uropean Standards exist for the design, the construction and stability of such protective screens. The manufacturer is advised to use his experience and state of the art in any particular spec
29、ific situation requiring such p1 aventative measure. OBSI 04-2000 STD-BSI BS EN 746-4-ENGL 2000 9 1624bb9 084185b O14 Page 11 EN 746-4:2000 In case of breakage of lifting appliance, chains, ropes or auxilliary equipment, steel parts could fall into the molten metal. Especially when lifting steel par
30、ts, load lifting appliances and carrying equipment exposed to the molten metal could break due to overload and reduced tensile strength because of the additional thermal stress. If these parts fall into the kettle, molten metal could be ejected. Slinging methods shall be used and these methods shall
31、 be included in the information for use. 5.3 Leakage or spillage of molten metal If molten metal leaks or spills, then persons standing close to or operating the hace could be burned by contact with the material. In addition flammable materials could catch fire. 5.3.1 Overflow of molten metal Workpi
32、eces immersed into the molten metal displace a part of that metal and thus the level of molten metal increases and can overflow. This increase could be considerable for small kettles andor voluminous workpieces. These facts shall be considered when determining the level of molten metal and when char
33、ging the kettle with workpieces. To meet this requirement, the ratio shall meet the following formula: = between 5 and 9 inclusive bath volume displaced volume 5.3.2 Losses due to leakage from or breakage of the kettle During usage, the wall thickness of steel vessels reduces due to the effects of t
34、he molten metal. At points with increased temperature load this wear is higher that at a point with low temperature load. In case of high thermal load, this wear is higher than that experienced with local wear of kettle walls and could occur within a relatively short period of time, and could lead t
35、o local breakage and the subsequent leakage of metal from the kettle. A procedure for checking the kettle wall thickness shall be given by the manufacturer in the information for use (see clause 7, Table 2). (1) 5.4 Overheating of the molten metal If a kettle of molten metal overheats this can cause
36、 excessive heat exposure, threatening the integrity of the container. The design shall predict the level of temperature overrun that the equipment can safely stand and incorporate appropriate provisions for overrun conditions. (1 and 2) The design shall provide means to contain temperatures within d
37、esign parameters and try to predict the effect of failure of the control devices intended to control temperature within these limits (e.g. by the use of an automatic temperature control, actuating optical/acoustical alarm andor cutting off the heating automatically, when reaching a defined critical
38、temperature limit). (1 and 2) OBSI 04-2000 Page 12 EN 746-412000 5.5 Hazard by chemical materials and substances Chemicals (e.g. fluxes) used in molten metal processing can, when subject to the heat of the process, give off fmes. Health hazardous effects could occur, depending on the kind of substan
39、ce used. Where necessary, the design shall provide effective exhausting (e.g. checked by artificial smoke procedure) of fmes from the galvanizing equipment (e.g. hoods, enclosures and exhaust ducts). (2) The manufacturer shall indicate the hazards incurred and the nature of the emanations, in partic
40、ular zinc oxide. Reference shall be made to EN 1093-4. Because the requirements of exhaust equipment vary with the nature of the equipment, it is not possible to give details of the exhaust equipment in this standard. (1 and 2) 5.6 Falis into the molten metal (only for batch processes) Equipment sha
41、ll be designed so that in combination with the requirements of 5.2, in the event of tripping or falling accidents, the risk of any part of the operatorss body entering the molten metal shall be minimized. The design of the equipment shall include combinations of kettle height above floor and kettle
42、setting thickness such that the sum of the height and reach (the distance over which the operator must gain access across the edge of the kettle to the surface of the molten metal) shall be not less than 0,9 m. The height of the top of the kettle above the floor shall be not less than 0,7 m. (1 and
43、2) Where kettles are designed and installed such that the top flange of the kettle is level with the floor or less than 0,7 m in height above the floor, suitably situated semi-permanent barriers and/or guard rails shall be used. The sum of the height of the guard rail and the distance fkom the edge
44、of the kettle shall be not less than 0,9 m. The height of the guard rail shall not be less than 0,7 m. (1 and 2) Where such kettles are not fitted with lip extraction systems, a toe board not less than 0,2 m height should be fitted to the long side of the kettle. Similar protection measures shall be
45、 applied along the short side of the kettle when operations such as ash reclamation are carried out. In such cases there shall be a space, containing no permanent steel structure, for a minimum distance of 1,5 m fkom the end of the kettle, covering the full kettle width. A toe board shall be fitted
46、on the short side of the kettle (not less than 0,2 m in height). If removal of the zinc ash or double dipping is made difficult or dangerous by the position of the guard rail, then it shall be permissible to remove the guard rail while such operations are carried out. The toe board shall remain in p
47、lace at all times. (1 and 2) 5.7 Ergonomic requirements Equipment control panels shall be in a good working position in accordance with EN 6 14-1 and CEN/TC 122NG4. (I and 2) In the case of the batch process, lifting equipment for charging or discharging shall be available for use (reference shall b
48、e made to prEN 1005-2: 1998). (1 and 2) Reference shall also be made to prEN 1005-3: 1998. (1) OBSI 04-2000 STD-BSI BS EN 74b-4-ENGL ZOO0 Lb24bb9 084L858 997 D Page 13 EN 746-4:2000 6 VERIFICATION OF SAFETY REQUIREMENTS AND/OR MEASURES Verification of the safety requirements and/or the preventative
49、measures given in Table 1 and clause 5 can be carried out by visual inspection, functional check or by a test to check a specific feature. The function of control safety devices (e.g. safety temperature limitation) shall be proven by an appropriate test. NOTE? The verification means have been annotated against the preventative measure in Table 1 and also in italics against the preventative measure described in clause 5. In most cases, verification by a test, when given, will be to a specific standard. This is quoted, in italics against the specific preventative meas
