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不锈钢法兰一般用于大口径管道拐弯处的连接，由于管径大，其壁厚也大，故需开坡口，坡口型式由工艺定，对人体能进入的大管径，大多采用“X”型坡口,可省工省料，对人无法进入的管道大多采用“V”型坡口,底层焊透即可,有要求的,采用单面焊双面成形。对用于管道工程的压力管道，其厚度大于等于4毫米时，必需开坡口。 而一般小口径管道弯头，多由工厂按标准生产成形弯头不用现场制作。不锈钢法兰一般用于常压或低压的大口径管道转弯处，经过放样、下料、拼焊而成，成本较低，而压力管道对焊接要求很严格，不论口径大小，一般采用机制的普通弯头，成本比不锈钢法兰高很多。长输管道多不采用短节拼装的弯头。利用管道的弹性自然弯管（又称弹性敷设）的曲率半径为管径的 500～1000倍。在管道线路转角较小或条件容许的情况下常采用自然弯管法。
不锈钢法兰按照《钢制对焊无缝管件》GB/T12459-2005、《钢板制对焊管件》GB/T13401-2005、《钢制对焊管件》SY/T0510-1998,长半径弯头的曲率半径是1.5DN,短半径的弯头的曲率半径是1.0DN，所以，要是3D以上的弯头，就应该叫做弯管，因为加工成型的方式也不同。对于弯管，长输管道上一般用5DN或6DN的曲率半径是为了通球考虑的，这个楼上也有人解答了，角度需要由设计文件确定，和弯头不同的是，弯管是带有直管段的，根据《油气输送用钢制弯管》SY/T5257-2005,一般DN500以下不小于250mm，DN500以上应不小于500mm。楼上也有朋友提到弹性敷设了，根据《输气管道设计规范》GB50231-2005 如果管道走向弯曲的曲率半径大于1000DN,采用弹性敷设，尽量减少管道附件。
Stainless steel flanges are generally used for large diameter pipe bend connection, as a large diameter, its wall thickness is also large, so need to groove, groove pattern set by the technology of large diameter can enter the human body, they use " X "-type groove, can save labor and materials, and most people can not enter the pipe with" V "groove, bottom penetration can have requirements, with one-side welding shape. The pressure on the pipes for pipeline projects, its thickness is more than equal to 4 mm, the need to groove. General small-diameter pipe elbow, more than the standard production by the plant site produced without forming elbows. Stainless steel flanges are generally used for pressure or low pressure, large diameter pipe bend, after setting out, cutting, welding made, low cost, and pressure pipe right Hanjie very strict, regardless of caliber Normally, common use of the mechanism elbow, the cost is much higher than the stainless steel flange. Pipeline many do not use a short section of the elbow assembly. The flexibility of using the natural bend pipe (also known as flexible installation) of the curvature radius of 500 to 1,000 times the diameter. Small corner in the pipe line or permitted under conditions of constant use of natural elbow. Stainless steel flange in accordance with the "seamless piece of steel welded" GB/T12459-2005, "plate system on the pipe pieces" GB/T13401-2005, "steel butt welding fittings" SY/T0510-1998, long radius bend radius of curvature is 1.5DN, short radius of the bend radius of curvature is 1.0DN, so, if the 3D above the elbow, should be called the elbow, because processing of forming different ways. For the elbow, general use of long-distance pipeline or 6DN 5DN radius of curvature is considered to pass the ball, the upstairs was also answered this question, point of need identified by the design documents, and elbow difference is that with the elbow is straight sections, according to the "steel pipe used in oil and gas" SY/T5257-2005, the following general DN500 not less than 250mm, DN500 above shall be not less than 500mm. Upstairs also has a friend that flexible installation, and under the "gas pipeline design" GB50231-2005 if the pipeline to bending radius of curvature is greater than 1000DN, with flexible installation, to minimize the pipeline accessories.