Application of Stainless Steel Pipe in Drinking Water in Developed Countries

1. Japan's tap water supply pipe enters the standardization track Before 1955, the water supply pipe in Tokyo, Japan, was commonly used galvanized pipe. From 1955 to 1980, a large number of plastic pipes and steel-plastic composite pipes were used. Although the water quality and leakage problems of the galvanized pipes were partially solved, the leakage of the water supply pipe network in Tokyo was still very serious. The leakage rate had reached an unacceptably high 40% to 45% in the 1970s, and the “hazardous water” was Problems have also gradually reflected that plastic pipes and steel-plastic composite pipes cannot meet the basic requirements for environmental protection.

The Tokyo Water Supply Bureau conducted a large number of experimental studies on the leakage problem for more than 10 years. According to the analysis, 60.2% of the leakage was caused by insufficient strength of the water pipe material due to the external force, and 24.5% of the leakage was caused by the unreasonable design of the pipe joint. 8.0 The leakage of % is caused by the unreasonable design of the pipeline circuit due to the high expansion rate of plastics. To this end, the Japan Waterway Association recommends improving the water pipe materials and connection methods. From May 1980, from the water supply auxiliary line to the water meter, all the water pipes with a diameter of 50 mm or less use stainless steel pipes, pipe joints, elbows, and taps. The result is a fundamental solution to the problem of water leakage. In 1982, Japan developed a stainless steel bellows, which allows pipe users to easily bend at any angle, greatly reducing the number of joints or even eliminating joints completely, saving installation time and costs.

In 1980, Japan established industrial standards (JIS G 3448 - Stainless Steel Pipes for General Plumbing). In 1982, the Japan Water Works Association developed "JWWA G 115 - Stainless Steel Pipes for Tap Water" and "JWWA G 116 - Stainless Steel Pipe Fittings for Tap Water". The standard, which was later developed as a standard for stainless steel corrugated pipes, was adopted by the Tokyo Water Authority in 1999 as a standard material for 316 stainless steel bellows, which indicates that stainless steel is used as a pipe for tap water and a water supply pipe in a building to enter a standardized track. With the increase in the rate of stainless steel from 11% in 1982 to over 90% in 2000, the amount of water leakage has dropped from 50,000 in the end of the 1970s to 2-3 in 2000 (caused by stray currents). Leakage at joints) The use of stainless steel water pipes has greatly reduced the water leakage rate.

In the 1980s, especially after the 0-157 pathogenic coliform poisoning in 1996, people paid more attention to water quality. Stainless steel pipes and water storage equipment that can obtain good water quality were widely welcomed and widely used. In addition, Japan is an area prone to earthquakes. During the Great Hanshin Earthquake in 1995, stainless steel tanks and pipelines were not damaged by earthquakes due to their high strength and excellent impact resistance, but they also assumed the task of supplying drinking water to people in the ruins. As a result, the outstanding seismic resistance of stainless steel tanks and pipes has attracted attention.

Nowadays in Tokyo, Japan, the penetration rate of stainless steel water supply pipes has reached almost 100%. All residential areas have installed stainless steel pipes, greatly improving water quality and enhancing earthquake resistance. Moreover, a large number of dual-use water transmission bridges (both for water pipelines and fly bridges) are also widely used in 304 or 316 stainless steel construction. Since 1983, nearly 3,000 stainless steel water transmission bridges have been constructed.

Japan has been using stainless steel pipes for 40 years. Stainless steel pipes are now recognized by the Japanese as "the best drinking water container material."

2. The U.S. government has promoted the use of stainless steel pipes for the development of U.S. stainless steel pipes, which began in the 1960s and prevailed in the 1990s. The US Environmental Protection Agency (EPA) makes rigid regulations on the selection of water pipe materials. The selection of pipe materials must meet the requirements of high quality, low maintenance, and long life. According to the National Standard/National Health** International Standard ANSI/NSF61-1997a established by the U.S. government in accordance with the 1996 Water Purification Act, “The use of stainless steel and ductile iron pipes is permitted for metal pipes used in drinking water.” Urban Tap Water Supply Pipes In the network, where the trunk pipe is reformed, stainless steel pipe and ductile iron shall be selected; the water pipe entering the tall building shall be the preferred stainless steel pipe. The latest 2003 version of the American International Standards Committee's plumbing and residential standards once again included this aspect, indicating that the use of stainless steel water pipes has been officially approved by the United States. Other countries such as the Canadian Ministry of Health, the Dutch Health Accreditation Committee and the World Health Organization also confirmed this standard. Nowadays, more and more countries require that the pipes and system components of the drinking water system must meet the above standards as a basis for health assurance. The first batch of materials meeting the requirements of the standard are 304/304L, 316/316L stainless steel.

In the United States, stainless steel has been successfully used in more than 100 drinking water treatment plants and delivery systems. New York's water system has been using stainless steel since the 1960s. The original drinking water distribution system in New York City was outdated and could not meet demand. On the basis of 15 years of assessment of alternative materials, the authorities adopted large-caliber column and other pipes in the city's water pipelines in 1993. 304L stainless steel, its goal is to make the system life up to 100 years. Water supply reforms in the Washington area also use stainless steel pipes. The main water supply pipeline for the water supply system in the Ford Stadium, Detroit's $300 million new stadium, includes direct drinking water pipes at all 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 built in the United States in 30 years.

The reason why the United States chose stainless steel is based solely on economic and health considerations. Stainless steel materials meet the EPA guidelines and are often used in applications where water quality is high and difficult to replace, requires low maintenance, and has a long service life. Although the first material cost is about 20%-50% higher than 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 It can be up to 100 years, so the total cost over the entire life cycle is the lowest.

In the United States, more than 30 drinking water treatment plants use stainless steel instead of ductile iron pipes. The main reason is cost savings. The use of stainless steel pipes in the Massachusetts water plant saves about US$50,000 in the cost of ductile cast iron, and the use of stainless steel pipes for 30 years is still bright.

3. European stainless steel pipes have gradually become popular. The main water supply pipes in some of the oldest cities in Europe are asbestos cement pipes and cast iron pipes, and the loss of water caused by leakage is as high as 40%. Since 1980, Germany has begun to make heavy use of stainless steel in tap water systems to save water resources. German Mapress company is Europe's largest pipe fittings manufacturer, with annual production of 40 million pipe fittings. Sales figures for 2001 show that stainless steel pipes accounted for 51% of its pipe sales, carbon steel pipes for 44% of sales, and copper pipes for only 5% of sales. As one of the world’s most watched sporting events, the Allianz football stadium in Munich, Germany, the vast majority of its water supply system uses stainless steel water pipes, because stainless steel has the most stable and reliable performance, clean and sanitary, Water pipes that can fully meet the requirements of the German construction standards for delivering drinking water must have a minimum life expectancy of 50 years.

Since 1995, Italian cities generally adopt a technology that does not require trenching to replace main water supply pipes with stainless steel pipes. Experience has shown that stainless steel pipes are resistant to corrosion, have high strength, can withstand ground subsidence and earthquakes, and have a lifespan of at least 70 years. Plastic pipes and other alternative pipes are more economical.

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

The British ** (Scotland) used copper pipes in the past, but the soft water quality in Scotland led to corrosion and failure of the copper pipes and serious water leakage. The government spent a lot of money to study the causes of failure and solutions. Later, the hot and cold water pipes were replaced with stainless steel pipes and fittings. After more than a decade of use, the use of stainless steel pipes and fittings was examined when the hot and cold water pipes were disassembled. The results showed that the stainless steel pipes and fittings were in excellent condition and showed no signs of corrosion.