1, Japan tap water supply pipes into the standardized track

Before 1955, galvanized pipes were commonly used in tap water supply pipes in Tokyo, Japan. From 1955 to 1980, plastic pipes and steel-plastic composite pipes were widely used. Although the water quality problems and leakage problems of galvanized pipes have been partially solved, the leakage phenomenon of Tokyo water supply network is still very serious. The leakage rate reached an unacceptable 40% ~ 45% in the 1970 s, and the problem of "hidden water" is also gradually reflected. Plastic pipes and steel-plastic composite pipes cannot meet the basic requirements of environmental protection.

Tokyo Water Supply Bureau has conducted a large number of experimental studies on the water leakage problem for more than 10 years. According to analysis, 60.2 percent of the water leakage is caused by insufficient strength of water pipe materials, 24.5 percent of the water leakage is caused by unreasonable design of pipe joints, and 8.0 percent of the water leakage is caused by unreasonable design of pipe lines due to excessive expansion rate of plastics. For this reason, the Japan Waterway Association recommends improving water pipe materials and connections. Since May 1980, stainless steel pipes, pipe joints, elbows and faucets have been used for water supply pipelines with a diameter of less than 50mm from the auxiliary trunk line to the water meter. As a result, the problem of water leakage has been fundamentally solved. In 1982, Japan also developed stainless steel bellows. Pipeline users can easily bend to any angle, greatly reducing the number of joints and even completely eliminating joints, saving installation time and cost. In 1980, Japan formulated the industrial standard (JISG3448-stainless steel pipe for general piping, in 1982, Japan Waterway Association formulated the standards of "JWWAG115-stainless steel pipe for tap water" and "JWWAG116-stainless steel pipe joint for tap water", and later formulated the standard of stainless steel corrugated pipe. In 1999, the Tokyo Water Supply Bureau used 316 stainless steel corrugated pipes as standard materials, indicating that stainless steel used as tap water pipelines and water supply pipelines in buildings has entered a standardized track. According to statistics from Tokyo's water department, with the stainless steel rate rising from 11% in 1982 to more than 90% in 2000, the number of water leaks correspondingly dropped from more than 50000 points per year in the late 1970 s to 2-3 points in 2000 (leakage at joints caused by stray current). The use of stainless steel water pipes greatly reduced the water leakage rate. After the collective poisoning of 0-157 pathogenic coliform bacteria in the 1980 s, especially in 1996, people paid more attention to water quality, and stainless steel pipes and water storage equipment that can obtain good water quality were generally welcomed and widely used. In addition, Japan is an earthquake-prone area. In the 1995 Hanshin earthquake, stainless steel water tanks and pipes were not damaged by the earthquake due to their high strength and excellent impact resistance, and they also assumed the task of supplying drinking water to people in the ruins. Therefore, the outstanding seismic capacity of stainless steel water tanks and pipes has attracted people's attention.

In Tokyo, Japan, the penetration rate of stainless steel water supply pipes has reached almost 100 percent, and stainless steel pipes have been installed in all residential areas, greatly improving water quality and enhancing earthquake resistance. Moreover, a large number of dual-use water transmission bridges (both used as water pipelines and passing bridges) are also widely used in 304 or 316 stainless steel construction, and nearly 3000 stainless steel water transmission bridges have been built since 1983.

Japan has used stainless steel pipes for 40 years. Now stainless steel pipe has been recognized by the Japanese as "the best drinking water container material". The use of stainless steel pipes in the United States began in the 1960 s and prevailed in the 1990 s. The U.S. Environmental Protection Agency (EPA) makes rigid regulations on the selection of water pipe materials, and the selection of pipes must meet the requirements of high water quality, low maintenance and long life. The National Standard/National Sanitation Fund International Standard ANSI/NSF61-1997a formulated by the U.S. government in accordance with the 1996 Water Purification Act clearly stipulates: "For metal pipes for drinking water, only stainless steel and ductile iron pipes are allowed." City water supply pipe network, where the main pipe transformation, all use stainless steel pipe and ductile iron; into the high-rise water supply pipe, the preferred stainless steel pipe. The latest 2003 edition of the American International Standards Committee's water pipe and residential standards include this aspect again, indicating that the use of stainless steel water pipes has been officially approved by the United States. Other countries such as Health Canada, the Netherlands Health Accreditation Board and the World Health Organization have also confirmed this standard. Now more and more countries require that the pipes and system components of drinking water systems must meet the above standards as the basis for health assurance. The first batch of materials that meet the requirements of this standard are 304/304L and 316/316L stainless steel.

In the United States, stainless steel has been successfully applied in more than 100 drinking water treatment plants and conveying systems. New York's water supply system has been made of stainless steel since the 1960 s. The original drinking water distribution system in New York City is aging and unable to meet demand. Based on a 15-year evaluation of alternative materials, the authorities introduced 304L stainless steel on a large-diameter vertical pipe and other pipes in the city's water pipeline in 1993, with the goal of achieving a system life of up to 100 years. Stainless steel water pipes have also been used on a large scale in the Washington area water supply renovation. The main pipeline of the water supply system in Ford Stadium, a 0.3 billion-built large sports ground in Detroit, USA, includes direct drinking water pipelines at various sales points, all of which are made of 304 stainless steel. In addition, stainless steel pipes have become the standard material for more than 1600 new urban sewage treatment plants in the United States in the past 30 years.

The reason why the United States chooses stainless steel is entirely based on economic and health considerations. Stainless steel materials meet the Environmental Protection Agency (EPA) guidelines and are often used for water quality requirements, difficult to replace, low maintenance, and long service life. occasion. Although the first material cost is about 20% to 50% higher than that of galvanized pipe, due to the excellent corrosion resistance of stainless steel, the installation and processing costs are greatly reduced, the daily operation and maintenance costs of the pipeline are also greatly reduced, and the service life of the water system can be Up to 100 years, so the total cost during the entire life period is the lowest.

More than 30 drinking water treatment plants in the United States have used stainless steel instead of ductile iron pipes, mainly because of cost savings. Massachusetts water plant due to the use of stainless steel pipes, than the use of ductile iron to save about $50000, and the use of 30 years of stainless steel pipes are still bright as new.

3, European stainless steel water pipes are gradually popularized

The main water supply pipes in some ancient European cities are asbestos cement pipes and cast iron pipes, and the water loss caused by leakage is as high as 40%. Since 1980, Germany began to use a large number of stainless steel materials in the tap water system to save water resources. German Mapress Company is the largest pipe fittings manufacturer in Europe, with an annual production of 40 million pipe fittings. Sales figures in 2001 showed that stainless steel pipe fittings accounted for 51% of its pipe fittings sales, carbon steel pipe fittings accounted for 44% of sales, and copper pipe fittings accounted for only 5% of sales. As one of the most watched sports events in the world in 2006-Allianz Munich Football Stadium, Germany, most of its water supply system uses stainless steel water pipes, because stainless steel has the most stable and reliable performance, clean and hygienic, and can fully meet the requirements of German construction standards for the delivery of drinking water pipes must have at least 50 years of life.

Since 1995, Italian cities have generally adopted a technology that does not require trenching to replace the main water delivery pipeline with stainless steel pipeline. Experience shows that stainless steel pipeline is corrosion-resistant, has high strength, can withstand ground subsidence and earthquakes, has a service life of at least 7O years, and is more economical than alternative pipes such as plastic pipes.

After 10 years of testing in Karls Koga City, Sweden, ductile iron and PVC buried water supply main pipes have all been replaced with 316 stainless steel pipes.

British hospitals (Scotland) used copper pipes in the past, but the soft water quality in Scotland led to corrosion and failure of copper pipes, resulting in serious water leakage. The government spent a lot of money to study the causes of failure and solutions, and then all the hot and cold water pipes were replaced with stainless steel water pipes and joints. After more than ten years of use, the cold and hot water pipes were disassembled to investigate the use of stainless steel pipes and joints. The results showed that the stainless steel pipes and joints were in excellent condition and showed no signs of corrosion.