建筑材料中的建筑给排水常用管材（Common pipes for building water supply and drainage in building materials）.doc

建筑材料中的建筑给排水常用管材（Common pipes for building water supply and drainage in building materials） Building materials commonly used in building drainage pipe editing: 1 plastic pipes Plastic pipe is a kind of product made by melting and molding synthetic resin and additive. Additives are plasticizers, stabilizers, fillers, lubricants, colorants, UV absorbers, modifiers and so on. The commonly used plastic pipe: hard polyvinyl chloride (PVC-U), high density polyethylene (PE-HD) pipe, cross-linked polyethylene pipe (PE-X), PP-R pipe (PP-R), polybutylene (PB), engineering plastics acrylonitrile butadiene styrene copolymer (ABS) etc.. 1.1 plastic pipe material composition determines the characteristics of plastic pipes. The main advantages of plastic pipes: (1) the chemical stability is good. It is free from the influence of the environmental factors and the composition of the medium in the pipeline, and has good corrosion resistance. (2) small thermal conductivity, low thermal conductivity, thermal insulation and energy saving. (3) the hydraulic performance is good, the pipeline inner wall is smooth, the resistance coefficient is small, not easy to fouling, tube flow area does not change with time, pipeline blocking probability. (4) relative to the metal pipe, the density is small, the material is light, the transportation, the installation is convenient, flexible, simple, and easy to maintain. (5) it can bend naturally or has cold bending property, and can use coil supply to reduce the quantity of pipe joint. 1.2 plastic pipe main drawback: (1) poor mechanical properties, impact resistance is poor, poor rigidity, poor flatness, and clip and hanger set density. (2) poor flame retardancy; most of the plastic products are flammable and decompose when burning; they release poisonous gas and smoke. (3) the coefficient of thermal expansion is large, so the expansion compensation must be emphasized. 2 plastic pipe performance 2.1 physical properties Physical properties of plastic pi