1.前言 HNG型管是三井金属公司与西德科拜尔金属公司共同协作开发的产品,为双层金属波纹结构直埋管。该管弯曲自由度大,产成品规格尺寸长,并可在工厂连续完成内套管、隔热层、外壳保护管及防腐层等几道工序,其主要特点如下: ·弯曲自由度大,加工管段尺寸长,施工时对地形、地质条件要求简单,敷设工期短。 ·热损失小,隔热效果优异,并可长期 1. Introduction HNG-type pipe is a product jointly developed by Mitsui Metals Co., Ltd. and West German Bayer Metals Co., Ltd. and is a double-layer metal corrugated structure direct-buried pipe. The pipe has a large degree of freedom of bending and a long dimension of the finished product. The inner casing, heat insulation layer, shell protection pipe, and anti-corrosion layer can be successively completed in the factory. The main features are as follows: Large bending freedom, processing The length of the pipe section is long, and the requirements for the terrain and geological conditions during the construction are simple, and the construction period is short. Low heat loss, excellent heat insulation effect, and long-term