一般没有什么规范，不过重要的管道还是建议使用锻打法兰，比如一些高温差或者管道有震动的地方，铸造法兰质量较差的可能会造成断裂，振裂，漏水等。
Generally there are no specifications, but forged flanges are recommended for important pipelines, such as in some places where the temperature difference is high or there is vibration in the pipeline. Poor quality of cast flanges may cause fracture, vibration cracking, leakage, etc.
铸造法兰生产效率较高，质量比较低，但是价格比较便宜。但是铸造法兰因缺陷多，比如气孔，夹砂，等不宜作有高压力高强度的法兰。铸造毛坯因余量小的优点在一些不重要的场合也是可以用的。锻打法兰就没有这些缺陷，高质量管道安装中非常常见。

Casting flange has higher production efficiency and lower quality, but its price is cheaper. But casting flange is not suitable for high pressure and high strength flange because of many defects, such as blowhole, sand juyixiban.07858.net guangyou.07858.netshuzhi.07858.netchejiareqi.07858.netruhuaji.07858.netwenbanji.07858.net

inclusion, etc. Casting blank can also be used in some unimportant occasions because of its small margin. There are no such defects in forged flange, which is very common in high quality pipeline installation.