At present, the variety of water supply materials is very diverse. Our focus is to introduce new indoor and outdoor water supply pipes, and to introduce some application points that have been used in the past. The following is a summary of the two major categories from the main places of use of pipes:
(1) Outdoor water supply pipe
Outdoor water supply pipes can be divided into two categories: metal pipes and non-metal pipes.
1, metal tube
At present, the outdoor metal water supply pipes that are widely used and applied mainly include steel pipes and water supply ductile iron pipes.
1.1 steel pipe
The steel pipe has the points of welded steel pipe and seamless steel pipe; in terms of anti-corrosion performance, it can be divided into protective layer type, unprotected layer type and texture type; according to wall thickness, there are ordinary steel pipe and thick steel pipe.
Welded steel pipes are divided into spiral seam welded and straight welded steel pipes. Spiral seam welded steel pipes are divided into automatic submerged arc welded steel pipes and high frequency welded steel pipes. Straight welded steel pipes are further divided into ordinary straight welded steel pipes and stainless welded steel pipes. The seamless steel tubes are divided into hot rolled tubes and cold rolled (drawn) tubes according to the manufacturing method, and the precision thereof is divided into ordinary and advanced. The cold-rolled (pull) pipe has a nominal diameter of 200 mm and the hot-rolled pipe has a nominal diameter of 600 mm. Seamless steel pipe also has stainless steel seamless steel pipe. Stainless steel seamless steel pipe is divided into hot rolled, hot extruded stainless steel seamless steel pipe and cold rolled (drawn) stainless steel seamless steel pipe.
There is no protective layer with or without protective steel pipe, which used to be called non-galvanized steel pipe (black iron pipe). The texture type steel pipe mainly refers to the stainless steel seamless steel pipe and the stainless steel welded steel pipe. It has not been promoted and applied due to the cost and connection in the outdoor large and medium pipes.
The protective layer type (mainly refers to the inner wall of the pipe) is now available in a metal protective layer type and a non-metal protective layer type. The metal protective layer type is commonly used as a surface plating protective layer type and a surface pressure protective layer type. Commonly used in the surface coating protection layer type is galvanized pipe. The galvanized pipe also has cold galvanized pipe and hot galvanized pipe. The hot galvanized pipe is still widely used because of its dense and uniform protective layer, strong adhesion and good stability. . The cold-galvanized pipe is not dense enough and uniform in stability, and its stability is poor. Generally, the service life is less than 5 years, it is rusted, and there are “red water” and “black water”. The smell of iron is serious, and all kinds of harmful bacteria exceed the national drinking water. The water quality standards have been banned in the domestic water supply pipelines. The surface pressure-protection layer type is also divided into a physical cover type composite steel pipe and a chemical blasting cover type composite steel pipe according to different production processes, wherein the physical cover type composite steel pipe has been produced with a steel double-stainless steel composite steel pipe and a copper-steel double-metal composite steel pipe. The physical softening method is adopted to press the heat-softened thin-walled stainless steel pipe or the cold-thin-wall copper pipe to the inner wall of the steel base pipe by a certain process. The specifications of these two pipes are DNl5-DN300 and DNl5-DNl50 respectively. The physical cover type composite steel pipe connection is mostly connected by special accessories. The chemical blasting covered composite steel pipe has a bimetallic composite pipe.
Non-metallic protective layer type has two categories: non-metal coated type and non-metal lining type. "Technical Regulations for Construction Water Supply Steel-plastic Composite Pipeline Engineering" (CECSl25:2001) (referred to as "Steel-Plastic Technical Regulations") The steel pipes are collectively referred to as steel-plastic composite pipes, and the basic materials of the steel pipes to which the steel-plastic composite pipes are attached are divided into coated (lining) plastic welded steel pipes and coated (lining) plastic seamless steel pipes. According to the different non-metallic materials coated (lining), the current industry standard "water-coated plastic composite steel pipe" (CJ/T120-2000) divides the water-coated plastic composite pipe into polyethylene (PE) steel-plastic composite pipe and epoxy resin. (EP) steel-plastic composite pipe, some manufacturers also produce ethylene-acrylic acid copolymer (EAA) steel-plastic composite pipe, "water supply lined plastic composite steel pipe" (CJ/T136-2001) divided water supply plastic-lined composite pipe into polyethylene (PE), hard polyvinyl chloride (PVC-U), cross-linked polyethylene (PEX), chlorinated polyvinyl chloride (CPVC) and polypropylene (PP) steel-plastic composite pipe. The manufacturer divides the steel-plastic composite pipe into three types: flange type, groove type and thread type from different pipe connection methods and accessories. According to the heat resistance of the coating (lining) layer, it is divided into hot-water steel-plastic composite pipe and ordinary Steel-plastic composite pipe for cold or cold water. In addition, depending on the way of coating, there are different types of external galvanizing and inner coating (grooved water-supply steel-plastic composite pipe, threaded water-supply steel-plastic composite pipe, etc.) and internal and external full-coated steel-plastic composite pipe (flange) Type of water supply steel-plastic composite pipe) difference. According to the metal material of the outer coating, the plastic-lined composite steel pipe is divided into an outer galvanizing type, an outer coating type and an outer galvanized aluminum alloy type lining plastic composite steel pipe (the manufacturer is also called an alloy steel-plastic composite pipe). In addition, there is a large class of injection-molded steel pipes. Currently, polypropylene (PP) and polyvinyl chloride (PVC) water supply pipes are known, but they are not confirmed in the Technical Specification for Steel Plastics. Steel-plastic composite pipe is a relatively good anti-corrosion pipe. The current large pipe diameter of steel-plastic composite pipe is DNl25-DN300, which is limited in the use of outdoor large and medium pipes.
The welded steel pipe for low-pressure fluid transportation and the galvanized welded steel pipe also have the difference between ordinary steel pipe and thick steel pipe. For welded steel pipes, the pressure-reducing capacity of the pipe wall is appropriately increased, and the cost is still a low-cost steel pipe for the seamless steel pipe type pipe. Seamless steel pipe is mainly reflected in the wall thickness varies with various grades and materials.
We know that the mechanical strength of steel pipes can withstand high internal and external pressures. The weldability of the pipe body facilitates the manufacture of various pipe fittings, and is particularly suitable for pipelines with complex terrain and high requirements. Corrosion is its shortcoming. However, the inner and outer protection of the steel pipe is properly handled and the service life is also very long. According to reports, a 1m diameter factory pipe of Shanghai Yangshupu Water Plant has been used for 60 years and is still very good.
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