含镉钎焊填料的哪些用途可视为出于安全原因的用途（REACH 附件 XVII 第 23 条第 9 款中的例外情况）？

含镉钎焊填料的哪些用途可视为出于安全原因的用途（REACH 附件 XVII 第 23 条第 9 款中的例外情况）？

Which uses of brazing fillers containing cadmium can be regarded as uses for safety reasons (derogation in paragraph 9 of entry 23 of Annex XVII to REACH)?

REACH法规附件XVII第23条第8款规定，钎焊填料中镉及其化合物的含量不得超过0.01%（重量百分比）。此外，如果镉（以金属镉表示）的含量超过0.01%（重量百分比），则不得将钎焊填料投放市场。该款还规定，钎焊是指使用合金并在450°C以上温度下进行的连接技术。根据下文第9款，作为例外情况，第8款不适用于国防和航空航天应用中使用的钎焊填料，也不适用于出于安全原因使用的钎焊填料。与此例外情况相关的安全方面是，使用含镉钎焊填料是否可以防止造成人员伤亡或环境污染的事故。为了便于执行，给出了应用示例。可以认为，第 23 条第 9 款中出于安全原因对含镉钎料使用的豁免涵盖了当前的用途，例如：发电厂技术中温度低于 650°C 的涡轮机叶轮中使用的钎料。发电厂技术中的涡轮机叶轮是气体压缩机和锅炉给水泵的速度驱动器的部件，其转速约为每分钟 1000 转 (rpm) 至 20 000 rpm。含镉钎料是必需的，因为它们可以在 650°C 以下使用而不会降低母材（基底金属）的强度。无镉钎料需要更高的温度，这会削弱母材。母材的削弱可能导致涡轮机叶轮损坏。由于高转速，碎片和弹片可能会对叶轮附近的工人和其他人造成伤害。涡轮机叶轮故障还可能导致发电厂、天然气管道压缩机站或炼油厂完全关闭。钎焊填料用于高压（1.5 – 17 bar）输送乙炔的管道。在连接输送乙炔的管道时，需要使用含镉钎焊填料，以避免形成爆炸性物质。乙炔会与铜、银以及其他材料生成爆炸性物质（例如生成乙炔铜和乙炔银）。镉会将钎焊填料中铜和银的总百分比降低到不会形成爆炸性物质的水平。在这种应用中，在钎焊填料中使用镉的另一个原因是，镉有助于毛细作用和焊料渗透，从而确保高压（1.5-17 bar）输送乙炔的管道获得高质量且高度完整的接头。由于乙炔是一种极易燃气体，无论是否与空气接触都具有爆炸性，因此管道和管子中乙炔的释放也可能造成严重风险。其他希望从豁免中受益的应用需要展示与上述类似的安全方面。这些考虑因素应考虑到市场上无镉钎焊填料的可用性，这些填料可以以等效的方式解决钎焊填料特定应用的安全问题。另请参阅 ECHA 的报告“出于安全原因使用含镉钎焊填料” [PDF]。

Paragraph 8 of entry 23 of Annex XVII to the REACH Regulation states that cadmium and its compounds shall not be used in brazing fillers in a concentration equal to or greater than 0,01 % by weight. In addition, brazing fillers shall not be placed on the market if the concentration of cadmium (expressed as Cd metal) is equal to or greater than 0,01 % by weight. The paragraph also states that brazing shall mean a joining technique using alloys and undertaken at a temperature above 450°C. In accordance with the following paragraph 9, by way of derogation paragraph 8 shall not apply to brazing fillers used in defence and aerospace applications nor to brazing fillers used for safety reasons.The safety aspect in relation to this derogation is if the use of cadmium containing brazing filler may prevent accidents causing human suffering or environmental pollution.For the enforcement purposes examples of applications are given. It can be considered that the derogation on uses of cadmium containing brazing fillers for safety reasons in paragraph 9 of entry 23 covers the current uses, such as:Brazing fillers used in turbine wheels in power plant technology in temperature below 650°C. Turbine wheels in power plant technology are parts of speed drivers for gas compressors and boiler feed pumps, where rotational speed is approximately from 1000 revolutions per minute (rpm) up to 20 000 rpm. Cadmium containing brazing fillers are needed as they can be used below 650 °C without decreasing the strength of the parent material (base metal). Cadmium-free brazing fillers require higher temperatures which causes the weakening of the parent material. Weakening of the parent material could lead to the breakdown of the turbine wheel. Due to high rotational speed the parts and pieces of shrapnel may cause injuries to workers and others in the vicinity of the wheel. The breakdown of the turbine wheel may result also in a complete shutdown of the power plant, the compressor station of a gas pipeline, or of a refinery.Brazing fillers used in pipes and tubes where acetylene is transferred in high pressure (1.5 – 17 bar).Cadmium containing brazing fillers are needed in the joining process for pipes and tubes, where acetylene is transferred in order to avoid formation of explosive substances. Acetylene forms explosive substances with copper and silver as well as other materials (e.g. formation of copper acetylide and silver acetylide). Cadmium reduces the overall percentage of copper and silver in the brazing fillers to the level where formation of explosive substances does not exist. Another reason to use cadmium in brazing fillers for this application is that cadmium facilitates the capillary action and solder penetration ensuring a good quality joint with high integrity for pipes and tubes where acetylene is transferred in high pressure (1.5-17 bar). Release of acetylene from pipes and tubes may as well cause serious risk, as acetylene is extremely flammable gas and explosive with and without contact with air.Other applications that would like to benefit from the derogation need to show the similar kind of safety aspects as described above.Such considerations should take into account the availability on the market of cadmium-free brazing fillers which can address the safety aspects of the specific application of the brazing fillers in an equivalent manner.See also ECHA´s report "The use of brazing fillers containing cadmium for safety reasons" [PDF].