In the history of the development of building water supply pipelines in my country, it has experienced an evolution process from galvanized steel pipes to plastic pipes (PP-R) to composite pipes to copper pipes and stainless steel pipes. Among them, galvanized steel pipes have long occupied a dominant position before 2000. Because galvanized steel pipes are not corrosion-resistant, they rust after long-term use, which leads to secondary pollution of water quality, yellow water, pipe scaling, bacterial growth and other problems, which seriously affect people’s health. Moreover, due to the influence of rust, the service life of galvanized steel pipes is generally only 8-12 years, and the problem of water leakage and maintenance during use is even worse. Due to the great economic differences between domestic regions, galvanized steel pipes still occupy a certain market in backward areas.

PP-R pipes have the advantages of corrosion resistance, environmental protection and long service life compared to galvanized steel pipes, so they have developed rapidly for some time. However, the unavoidable shortcomings of plastic pipes themselves are also exposed during use. The main problems are severe deformation due to heat and cold cracking. Aging is accelerated by sunlight or hot and cold changes, and it is easy to burn. Due to the insufficient standardization of the market development in my country, the investment threshold of plastic pipe manufacturers ranges from hundreds of thousands to hundreds of millions of yuan, and manufacturers are rampant and disorderly competition is serious. In order to reduce production costs and seize the market, small enterprises cut corners in the production process, and low-priced and low-quality products flood the market. Affected by this, the further promotion of PP-R pipes has been greatly restricted. After four years of development, there are now several large enterprises with over 100 million yuan of investment to survive and develop.

Composite pipes are a transitional product on the historical stage of pipelines. The so-called composite pipe is a composite of metal and plastic, with two types of inner plastic coating and outer plastic coating, 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 in use, plastic and metal debonding and stratification, dislocation of joints and other problems occur, resulting in large-scale water leakage in the pipeline. This has occurred in a large number of domestic engineering examples.

As a high-end new type of pipe, copper pipes are highly respected by the industry. The main advantages of copper pipes are durability and good hygienic properties, especially the copper ions that are free in the pipe water have a certain bactericidal effect. However, copper pipes have not been widely promoted and used in the market. The reasons are mainly the following: First, the cost is high. Copper is a limited resource. Under the current national conditions, the high price limits its scope of use; second, there is controversy over the quality of domestic copper, and copper pipes often have verdigris (oxidation and rust) during use; third, the construction is difficult. Copper pipes are connected by welding, which requires relatively high welding technology.

In summary, in my country’s building water supply pipeline system, the four major problems recognized by the industry – pipeline leakage, secondary water pollution, short life of water pipes, and troublesome pipeline construction – have not been effectively solved. However, with the rapid development of the national economy, the improvement of people’s living standards and the grade of buildings, there is an increasing need for a new type of water supply pipeline that is environmentally friendly, hygienic, safe and leak-proof, economical and durable, and easy to construct. Under such historical conditions, thin-walled stainless steel pipes have entered the historical stage of the pipeline revolution as an emerging water supply pipe material. Stainless steel materials are environmentally friendly, corrosion-resistant, durable, have smooth inner walls, low water flow loss, are luxurious and beautiful after polishing, and have a cost-effectiveness that exceeds any existing water supply materials. Once they were released, they were widely valued by the industry.

1. Large demand for building water supply pipelines

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

2. Pipeline direct drinking water is developing rapidly.

The direct drinking water industry has gradually developed in China, but due to different regional economic levels, it has developed rapidly in developed cities and slowly in underdeveloped regions. In June 2005, the Ministry of Construction promulgated the new “Urban Water Quality Standards”, which proposed higher drinking water indicators. In August 2006, the industry standard “Technical Regulations for Pipeline Direct Drinking Water Systems” (CJJ 110-2006) came into effect. 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 regions 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 yuan. According to the proportion of direct drinking water pipes accounting for 15% of the entire direct drinking water market and thin-walled stainless steel accounting for 65% of the direct drinking water pipe market, there is a market of about 10 billion yuan.

In the direct drinking water delivery pipeline, thin-walled stainless steel pipes are undoubtedly the best with their excellent performance of hygiene, beauty, high strength and high cost performance.

3. Domestic substitution for imports has a bright future.

The promotion and application of domestic thin-walled stainless steel pipes is showing a trend of replacing imported pipes. At present, the production and use of domestic thin-walled stainless steel pipes and pipe fittings are gradually increasing, and the production technology has also been improved to a certain extent. Localization reduces the cost of use and promotes the improvement of technical capabilities, making thin-walled stainless steel pipes acceptable to national conditions. Replacing imported pipes is an inevitable development and has a very bright future.