The standards of many five-star hotels require the use of copper pipes for the water supply system, but due to cost and market reasons, more and more hotels now also accept the use of stainless steel pipes. This article mainly makes a technical comparison between copper pipes and stainless steel pipes. ,for reference.
1. Comparison of copper pipe and stainless steel pipe
Now compare the physical performance, hygienic performance, corrosion resistance and economic value of the materials.
1) Comparison of physical properties
Comparison of tensile strength:
Taking the commonly used thin-walled stainless steel pipe made of 304 as an example, its tensile strength is 530-750Mpa, which is twice that of galvanized pipe and three times that of copper pipe. Therefore, the thin-walled stainless steel pipe can be made thinner (0.6MM) than the copper pipe, which is in line with the national industrial policy of saving materials, has a guarantee of strength, and can achieve the purpose of reducing the load-bearing of buildings
2) Comparison of thermal conductivity:
The thermal conductivity of thin-walled stainless steel pipe is 15 W/m°C (100°C), which is 1/4 of that of carbon steel pipe and 1/23 of that of copper pipe. Thin-wall stainless steel pipes are especially suitable for hot water transportation due to their good thermal insulation performance. Whether it is the thickness of the insulation layer, or the construction and maintenance costs of the insulation structure, the thin-wall stainless steel pipes have good economical efficiency.
3) Comparison of thermal expansion coefficients:
The average coefficient of thermal expansion of thin-walled stainless steel pipes is 0.017mm/(m°C), which is close to that of copper pipes. Metal pipes should be used for hot water transportation.
The inner wall of the thin-walled stainless steel tube is smooth after the internal and external finishing treatment, and the equivalent roughness Ks of the inner wall of the tube is 0.00152mm, which is smaller than that of the copper tube.
Therefore, the use of thin-walled stainless steel pipes has greater water flow, smoother water flow, better corrosion resistance, and effectively reduces noise
2. Comparison of hygienic performance
The stainless steel water pipe eliminates the problem of "red water, blue-green water and hidden water". It has no peculiar smell, no scaling, no harmful substance precipitation, keeps the water quality pure, and is harmless to the human body.
Decades of foreign use practice and laboratory tests in different countries have shown that the precipitation of stainless steel metal elements is more than 5% of the standard value stipulated by the WHO and the European Drinking Water Act (all countries in the world refer to these two standards). Low.
In fact, the stainless steel material itself is safe, non-toxic, and has good cleaning properties, which have been fully proved by the decades of successful application of stainless steel in various fields related to human health, and have become a well-known fact.
Stainless steel has not only been used for a long time in the food industry, including beverage, dairy, brewing, pharmaceutical industry, tableware and cooking utensils, and has become a standard material in these industries, but also widely used in medical human implants that require extremely high material safety and cleanliness Such as various brackets, artificial joints and steel nails in the body, etc., and become the standard material for clean rooms in the semiconductor industry that require extremely high cleanliness.
It is well known that copper pipes are prone to corrosion and produce patina.
Copper pipes suffer from excess copper, corrosive bitter odor from blue-green water due to corrosion, and scaling. The "patinous green" that occurs in copper pipes is mainly composed of copper carbonate, copper hydroxide compound [cuco3.cu(on)2] and copper sulfate (cuso4), which is easy to weather and dissolve in water. Although it can inhibit fungi, it has no effect on Bacterial effects are poor, toxic and also used as insecticides, which have astringent, stimulating and corrosive effects on the mucous membranes in the human body.
It can cause reflex vomiting and has a strong stimulating effect on the intestinal tract. Modern medical research shows that drinking water with excessive copper (whether it reaches the level of blue-green water or not) is extremely harmful to health.
3. Comparison of corrosion resistance
Because the thin-walled stainless steel tube can passivate with the oxidant, forming a tough and dense chromium-rich oxide protective film on the surface of chromium trioxide (Cr2O3), which can effectively prevent the further occurrence of oxidation reaction, while the passivation ability of copper tube is very good. This is the key reason why the corrosion resistance of copper pipes is far inferior to that of thin-walled stainless steel pipes.
When using copper pipes, it is necessary to control the chemical composition and speed of the water, otherwise it will cause corrosion of the pipes. For example, the corrosion of copper pipes will increase significantly in water with pH<6.5 or residual chlorine content>70ppm, and soft water will also lead to increased corrosion. When using copper pipes, the water velocity should not exceed 2 m/s, otherwise the corrosion rate will increase significantly.
When the flow rate reaches 2 m/s, the corrosion degree of the copper pipe is about 3 times that of the thin-walled stainless steel pipe, and when the flow rate is greater than 6 m/s, the corrosion degree will be as much as 20 times that of the thin-walled stainless steel pipe.
In addition, the surface of the copper pipe is also easy to corrode.
4. Comparison of economic value
The Chrysler Building, located in New York, USA, was built between 1926 and 1931. It is 318.9 meters high and has 77 floors. It is the first building in the world to use stainless steel materials in its exterior.
Despite its coastal and polluted location, the stainless steel on it still shines after 80 years, with only two cleanings in between.
From the Chrysler Building in New York, the Petronas Towers in Kuala Lumpur to the Disney Concert Hall in Los Angeles made of stainless steel, and Waterloo Railway Station in London, England; For structural parts, stainless steel, as the most sustainable green building material, exudes a unique charm that ordinary materials do not have all over the world.
These are excellent examples of the timeless nature of stainless steel.
From the analysis of the use of thin-walled stainless steel pipes at home and abroad, the service life of thin-walled stainless steel pipes and water pipes is the same as that of buildings, which is equivalent to that of copper pipes.
Theoretical weight calculation formula of thin-walled stainless steel:
Weight per meter = (outer diameter - thickness) × thickness × pi × density ÷ 1000
Price comparison of pipes: Due to the high price of copper raw materials, the price of copper pipes is the highest, and the price of thin-walled stainless steel pipes is about 40% lower than that of copper pipes. Therefore, the economic value of thin-walled stainless steel pipes is obviously better than that of copper pipes.
Thin-walled stainless steel pipes have a lower life cycle cost than copper pipes.
Because once the thin-walled stainless steel pipes are used, they do not need to be replaced within the 100-year life cycle, while other pipes cannot achieve such a long service life. As long as they are replaced once in the 70-year life of the building, the overall cost will be at least 2 to 4 times the initial investment of thin-walled stainless steel pipes and water pipes.
In fact, the choice of stainless steel water pipes not only has a low initial investment, but also has a very low life cycle cost. This is the biggest economic advantage of stainless steel that other materials cannot match.
3. Summary
Both stainless steel pipes and copper pipes are high-quality water supply metal pipes. It is more common to use copper pipes as water supply pipes abroad because the price of copper in foreign countries is relatively cheap, and the development time in foreign countries is relatively long.
With the development of domestic stainless steel pipes, many international brand star hotels now also use stainless steel pipes. The prospect of stainless steel pipe application will only become wider and wider in the future. The majority of pipe manufacturers should deploy in the precision stainless steel tube making machine as soon as possible to occupy the market, and Hangao Tech (SEKO Machinery) will be your reliable partner.
Iris Liang
Hangao Tech (SEKO Machinery) Technology Co., Ltd
Add: No.13 of Haiyu 2nd Road, Fuyu Village, Leliu, Shinde, Foshan City, Guangdong Province, China
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