In the history of the development of building water supply pipelines in China, it has experienced the evolution from galvanized steel pipes-plastic pipes (PP-R)-composite pipes-to copper pipes and stainless steel pipes. Among them, galvanized steel pipe occupied a major position for a long time before 2000. Because the galvanized steel pipe is not resistant to corrosion, the pipeline is rusted after long-term use, which leads to secondary pollution of water quality, yellow water, pipeline scaling, bacterial growth and other problems, which seriously affect people's health. Moreover, due to the influence of corrosion, the general service life of galvanized steel pipe is only 8-12 years, and the problem of water leakage and maintenance during use is even worse. Therefore, at the end of 1999, China's Ministry of Construction and other four ministries and commissions jointly issued a document clearly banning galvanized steel pipes in new residential buildings from June 1, 2000, thus opening the prelude to the reform of pipeline materials. However, due to the great economic differences in domestic regions, galvanized steel pipes still occupy a certain market in backward areas.

Since the state has not clearly defined alternative products after the ban on galvanized steel pipes, and due to the limitation of economic capacity, plastic pipes represented by PP-R (random copolymer polyethylene) temporarily dominate the water supply pipeline market. Compared with galvanized steel pipe, PP-R pipe has the advantages of corrosion resistance, environmental protection and long use time, so it has been developing rapidly for a period of time. However, the unavoidable shortcomings of the plastic pipe itself are also exposed in use. The main problem is serious thermal deformation and cold crack. By sunlight or hot and cold change aging speed, easy to burn, etc. Due to the development of China's market is not standardized enough, the investment threshold of plastic pipe production enterprises from hundreds of thousands to hundreds of millions of yuan, the proliferation of manufacturers, disorderly competition. In order to reduce production costs and seize the market, small enterprises cut corners in the production process and flood the market with low-cost and inferior products. Affected by this, the further promotion of PP-R tube has been greatly restricted. After four years of development, there are now several large enterprises with over 100 million investments to survive and develop.

composite pipe is as a transitional product on the historical stage of the pipeline. The so-called composite pipe is a composite of metal and plastic. There are two kinds of inner plastic and outer plastic, and the two materials are glued together. Due to the different properties of the two materials, the linear expansion coefficient of plastic is more than 4 times that of metal. Therefore, due to temperature changes, problems such as plastic and metal degumming and delamination, joint dislocation, etc., have occurred in a large area of pipeline water leakage. This is the case in a large number of domestic engineering examples.

copper pipe as a high-grade new pipe, has been respected by the industry. The main advantage of copper pipe is durable, and the sanitary performance is better, especially the copper ion free into the pipeline water has a certain bactericidal effect. But the copper pipe has not been widely used in the market. The main reasons are as follows: first, the cost is high, copper is a limited resource, and the high price limits its scope of use under the current national conditions; second, the quality of domestic copper is controversial, and copper pipes often have patina (oxidized rust) in use; third, the construction is difficult, copper pipes are connected by welding, which requires relatively high welding technology.

Based on the above situation, in my country's building water supply pipeline system, the four major problems recognized by the industry-pipeline leakage, secondary pollution of water quality, short water pipe life, and pipeline construction troubles-have not been effectively resolved. However, with the rapid development of the national economy, people's living standards, the improvement of building grades, more and more need a new, environmental health, safe, economic durability, convenient construction of water supply pipeline. Under this historical condition, thin-walled stainless steel pipe as a new water supply pipe boarded the historical stage of the pipeline revolution. Stainless steel materials are environmentally friendly, corrosion-resistant, durable, smooth inner wall, small water flow loss, luxurious and beautiful after polishing, and cost-effective beyond any existing water supply materials. Once available, they have received widespread attention from the industry.

, large demand for building water supply pipelines
According to the "Ninth Five-Year Plan for Construction and the Outline of Long-Term Goals for 2010", the demand for cold and hot water pipes in residential building areas was 0.4 billion meters from 2001 to 2010. In addition, the demand for heating pipes is about 0.2 billion meters, the demand for cold and hot water pipes in other buildings is about 0.1 billion meters, the demand for floor radiant heating pipes is about 0.4 billion meters, and the demand for cold and hot water pipes in solar water heaters is about 20 million meters per year. In addition, the average annual renewal of cold and hot water pipelines in many hotels in our country is 20 million meters, the annual pipeline demand for building renovation projects is about 20 million meters, the annual demand for industrial pipelines is about 20 million meters, and the annual demand for medical and food production pipelines is about 20 million meters. According to the above calculations, the annual demand for construction pipelines in China is about 1.2 billion meters from 2001 to 2010. According to authoritative sources, the demand for stainless steel pipes will reach 300000 tons by 2010. According to the proportion of thin-walled stainless steel pipes accounting for 60% of stainless steel pipes, with an average of 1kg per meter, the total amount is 0.18 billion meters, accounting for 15% of the total demand for pipes, and there will be a market share of more than 6 billion yuan.

Due to the differences in economic conditions in various regions of the country, different building requirements, various pipelines have a certain market, but from the application of developed areas, the use of thin-walled stainless steel pipes is gradually expanding, with The improvement of the economic level of underdeveloped areas will also be developed and applied to a certain extent.

2. Pipeline direct drinking water has developed rapidly.
It is reported that 133 river sections in 138 cities across the country have been polluted in different ways, and 78% of the river sections are not suitable for drinking water. 50 per cent of urban groundwater is contaminated; about 70 per cent of the country's population consumes contaminated water. With the development of national economy, the health problem of drinking water has been paid more and more attention. As early as 1995, President Jiang Zemin issued an instruction to "vigorously develop drinking water projects and improve the quality of drinking water for citizens". Since then, the direct drinking water industry has gradually developed in China, but due to different regional economic levels, it has developed in developed cities in China. Rapid, relatively slow development in underdeveloped areas.

In June 2005, the Ministry of Construction promulgated the new "Urban Water Supply Quality Standards", which proposed higher drinking water indicators. In August 2006, the industry standard "Technical Specification for Pipeline Direct Drinking Water System" (CJJ 110-2006) began to be implemented. The implementation of these two standards has greatly promoted the large-scale development of the direct drinking water industry. By 2007, the direct drinking water industry has grown into a market with an annual output value of nearly 10 billion yuan. The penetration rate of direct drinking water in developed areas such as Beijing, Shanghai and Guangzhou has reached 10%, and medium-sized cities are also actively implementing or planning. It is estimated that the capacity of the entire domestic direct drinking water market is 100 billion. According to the proportion of direct drinking water pipelines accounting for 15% of the entire direct drinking water market and the proportion of thin-walled stainless steel accounting for 65% of the direct drinking water pipeline market, there is about 10 billion of the market.

In the direct drinking water pipeline, the thin-walled stainless steel pipeline is undoubtedly second to none for its excellent performance of hygiene, beauty, high strength, and high cost performance.

3, domestic alternative imports have a bright future. The popularization and application of
domestic thin-walled stainless steel pipe is the trend of replacing imported pipe. At present, the production and usage of domestic thin-walled stainless steel pipes and fittings are gradually increasing, and the production technology has also been improved to a certain extent. Localization reduces the cost of use, promotes the improvement of technical capabilities, and enables thin-walled stainless steel pipes to be accepted by national conditions. It is inevitable to replace imported pipes for development and has a very broad future.