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发表于 2010-12-5 14:31:11
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本帖最后由 烟不离手 于 2010-12-6 08:39 编辑
不知道论坛内有多少人在使用RCC-M规范（目前国内80%以上的核电站的核岛机械设备依据此规范建造），在RCC-M规范的F8140章节中，对热电偶与工件的直接接触有明确规定（英文版原文抄录如下——来自RCC-M F8140）。但是该规范中也明确指出：“ 如果给加热炉配置了不与批量件、部件和零件相接触的高温计，制造商和供应商就不需要符合上述条款（热电偶和工件直接接触——烟不离手注）的要求。在此情况下制造商和供应商要提供证明这一种方法与热电偶测量方法相当的理由。此证明要保留给监督者使用。非接触式测温装置要在测量操作条件下标定，标定周期应少于两个月。”一直纳闷，这里所说的高温计是一种什么样的测温元件？还望有知道的指点一二。
个人觉得，一是直接接触式测温可以反应当前工件的实际温度；再就是RCC作为核电界影响很大的核电站建造规则，力图给出的每一个信息都准确而唯一，便于标准化作业；就算目前不能实现标准化的，也尽可能多的收集实际的数据，便于下一版次修订时能加以规范。因为在实际操作中，如果热电偶不与工件接触，炉型不一样，炉子空间大小不一样，加热介质不一样，热能传递方式不一样，工件大小不一样，非接触式测温的热电偶与工件的距离也就不同，各个制造厂在执行规范时，虽然仪表的显示温度都一样，工件的实际温度可能就会有很大的差异。最终，导致不同厂家按同一规范作出来的产品的性能也会有很大差异。
回到楼主的问题，现在很多客户或有意，或模仿，都在这么要求制造厂，其实对促进我国的制造业规范化、标准化作业是一件好事！
下面是RCC-M F8140——2007版英文版的原文。
F 8140 HEAT TREATMENT TEMPERATURE
MEASUREMENT AND RECORDING
a) Temperature shall be measured by means of thermocouples placed on the load itself, on the
component or part thereof, or fixed to blocks in close contact with the part. Thermocouples
shall be shielded from radiation from the furnace and the atmosphere by a protective shield,
and shall be sufficient in number:
- to ensure that the load, the entire component or the section being treated is within the
required temperature range. In the case of heat treatment of a component or section thereof,
at least one thermocouple shall be placed on one of the thickest parts of the component and
at least one other on one of the thinnest parts. In the case of a load comprising several parts,
at least one thermocouple shall be placed on one of the parts at the centre of the load,
- to verify the absence of harmful temperature gradients.
However, the Manufacturer or Supplier need not comply with the above requirements if the
furnace is provided with special measuring devices not in contact with the load, component or
part. In such a case, the Manufacturer or Supplier shall provide justification by demonstrating
that the latter method is equivalent to the thermocouple method of measuring the temperature.Such justification shall be kept available for the Surveillance Agent. Temperature measuring
devices not in contact with the load, component, or part shall be tested under operating
conditions at less than 6-monthly intervals and whenever the heat conditions change (e.g. after
furnace overhaul). This requirement shall not apply to heat treatment of component parts as
defined in paragraph S 7542 b 2.
b) The main parameters concerning heat treatment, time and temperature shall be continuously
and automatically recorded. This applies also to the throughput rate in the particular instance of
a continuous feed furnace. Continuous readings are not required for cooling outside the
furnace, forming operations and heat treatments before and after welding. It shall be verified
throughout the duration of the treatment that the requirements of a) above are met.
c) The design of the furnace and its loading characteristics shall be such that the maximum
permissible deviation of the "obtained temperatures" at each point of the load, with respect to
the holding temperature specified by the Manufacturer, shall be ± 15°C for the entire load,
except where the procurement specification stipulates a different permissible deviation.
d) Each recording chart and channel shall be coded so as to permit identification of the relevant
load, component, section of component or weld. A sketch showing location of the
thermocouples shall be attached to the recording chart so that each channel can be related to the
location.
e) All time, temperature and throughput recordings shall be retained and kept available. The heat
treatment report shall refer to these recordings and shall give the characteristics of the thermal
cycles obtained to enable comparison with the cycle stipulated in the manufacturing
programme. |
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IP卡
发表于 2010-12-5 09:57:28
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楼主
发表于 2010-12-6 08:33:44
