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AWS C7.1M/C7.1:2013 pdf free download
AWS C7.1M/C7.1:2013 pdf free download.Recommended Practices for Electron Beam Welding and Allied Processes.
should not be allowed to enter the chamber enclosure after welding until concentrations of airbrne contaminants (particularly, ozone, oxides of nitrogen, and other toxic gases) that may be present have been reduced to safe levels.
Materials that can be welded by the electron beam process include some with well known toxic properties (beryllium. for example). The possible toxic properties of a workpiece should be determined prior to processing with an electron beam, and adequate protection should be provided to personnel in accordance with ANSI Z49. I, Safely in Welding. Cutting, and Allied Processes and any other local regulations. Before welding any unfamiliar material, the Material Safety Data Sheet (MSDS) should be read to deternilne whether any hazards exist.
It is very unlikely that the air left in a high vacuum electron beam chamber would be sufficient to give rise to ozone and oxides of nitrogen in concentrations above the permissible exposure level as given in the Code of Federal Regulations. However, adequate area ventilation should be employed to maintain concentrations of airborne contaminants around the equipment below permissible exposure levels, and proper exhausting techniques should be employed to maintain residual concentrations in the chamber (or enclosure) below these same limits. Likewise, care should be taken while cleaning the interior of the vacuum chamber to ensure that fumes from the solvents and cleaning solutions do not reach hazardous levels.
When employing EBW-NV mode, where welding is done in atmosphere (and thus where concentrations of ozone and oxides of nitrogen could easily exceed permissible limits), an externally vented weld area exhaust system should be employed.
4.2.4 Visible Radiation. Direct viewing of visible radiation emitted during operation of electron beam equipment can be harmful to eyesight. Since the intensity of the emitted light varies with the electron beam power and (he composition of the workpicce. no precise guidelines can be stated. Infrared and ultraviolet radiation is normally a viewing hatard. hut the leaded glass used in electron beam equipment viewing ports and optical systems provides sufficient protection.
Light ernined during EBW is produced by radiation from the molten metal in the weld pool. The intensity of radiated light increases with the temperature of the metal. Since the visible light emitted during welding on high-melting point materials is too bright ftr direct viewing, special care shall be taken to ensure that an adequate eye protection filter is employed. Guidelines for selecting a suitable filter are difficult o establish, due to many factors that affect the choice. These factors include the distance and angle of viewing. optics employed (magnification, aperture, etc.), workpiece material, and beam power. However, as a general guideline, the filter used should be of sufficient density so that the viewer’s eyes are comfortable during the highest level of light intensity encountered and so that there is no evidence of eye irritation after exposure.AWS C7.1M/C7.1:2013 pdf free download.
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