1986年5月至8月全国沼协调查的,冬季印发的“沼气集中供应系统工程考察报告”小册子第18页载“硬质聚氯乙烯和聚乙烯塑料管具有质轻、价廉、抗腐蚀。摩擦阻力小、接口严密、抗拉强度大以及施工简便等一系列优点。由于塑料管件埋地敷设时可避免紫外线照射、减缓老化速度和延长使用寿命,因此,一些集中供气管网已开始 May 1986 to August investigation of the National Association of marsh, published in winter, “biogas centralized supply system engineering inspection report” on page 18, "hard PVC and polyethylene plastic pipe with a light, inexpensive, anti- Corrosion. Frictional resistance is small, tight interface, tensile strength and ease of construction and a series of advantages. As the laying of plastic pipe buried to avoid ultraviolet radiation, slow down the aging and extend the service life, therefore, some of the central air supply network has Start