Stainless steel pipes are the most durable.

It's good that galvanized pipes can last for ten or eight years.

Stainless steel pipes can be used for a lifetime.

In terms of price?

Stainless steel pipe is more expensive than galvanized pipe 10 times.

The advantage of galvanized pipe is its low price.

Stainless steel pipe saves the usual processing cost once and for all.

Brief introduction of galvanized pipe

Galvanized pipe, also known as galvanized steel pipe, is divided into two types: hot dip galvanizing and electro-galvanizing. Thick galvanized coating, uniform coating, strong adhesion and long service life. The cost of galvanizing is low, the surface is not very smooth, and the corrosion resistance is much worse than that of hot galvanized pipe.

Nominal wall thickness mm 2.0 2.5 2.8 3.2 3.5 3.8 4.0 4.5

Coefficient c1.0641.051.0451.0401.0361.0341.028.

Grade of steel: q 215a; ; q 2 15B； Q235AQ235B

Test pressure/MPa: d10.2-168.3mm is d3MPaD 177.8-323.9mm is 5mpa.

Theoretical weight table and formula of galvanized pipe

Theoretical weight formula of galvanized pipe: (diameter-wall thickness) x wall thickness x0.02466* 1.0599= weight per meter (kg/meter).

Main applications

Galvanized pipes, which are often mentioned, are mainly used for gas transmission and heating. As a water pipe, galvanized pipe produces a lot of rust after several years of use. The yellow water not only pollutes sanitary ware, but also is mixed with bacteria growing on the unsmooth inner wall. Corrosion leads to high content of heavy metals in water, which seriously harms human health. In 1960s and 1970s, developed countries began to develop new types of pipes and gradually banned galvanized pipes. China Ministry of Construction and other four ministries and commissions also issued a document explicitly prohibiting galvanized pipes from 2000.

Brief introduction of stainless steel pipe

Stainless steel pipe is an economical section steel, an important product in iron and steel industry, and has a wide range of uses.

stainless steel tube

Used in life decoration and industry, many people in the market use it to make stair handrails, window covers, railings, furniture and so on. Common materials are 20 1 and 304.

It accounts for about 8%- 16% of the total steel and is widely used in the national economy. Because steel pipes are hollow, they are most suitable for conveying liquids, gases and solids. At the same time, compared with round steel with the same weight, steel pipe has larger section coefficient and higher bending and torsion strength, so it has become an important material in various mechanical and building structures. Under the same weight, structures and parts made of stainless steel tubes have larger cross-sectional modulus than solid parts. Therefore, stainless steel pipe itself is a kind of economical section steel which saves metal and is an important part of high-efficiency steel, especially in oil drilling, smelting and transportation industries. Secondly, geological drilling, chemical industry, construction industry, machinery industry, aircraft and automobile manufacturing, as well as boiler, medical equipment, furniture and bicycle manufacturing also need a large number of various steel pipes. With the development of new technologies such as atomic energy, rockets, missiles and aerospace industry, stainless steel pipes play an increasingly important role in national defense industry, science and technology and economic construction.

Stainless steel pipes are safe, reliable, hygienic, environmentally friendly, economical and applicable. The successful development of thin-walled pipes and reliable and simple new connection methods has made them have more irreplaceable advantages, and their applications in engineering will be more and more popular, which has a good prospect in www.bxgb304.com. ? Because stainless steel has many ideal properties required by building materials, it can be said to be unique among metals, and its development continues. In order to improve the performance of stainless steel in traditional applications, the existing types have been improved, and new stainless steel is being developed to meet the strict requirements of advanced building applications. Due to the continuous improvement of production efficiency and quality, stainless steel has become one of the most cost-effective materials chosen by architects.

Stainless steel combines performance, appearance and use characteristics, so it will still be one of the best building materials in the world.

With the implementation of China's reform and opening-up policy, the national economy has achieved rapid growth, and the construction of a large number of urban houses, public buildings and tourist facilities has put forward new requirements for hot water supply and domestic water supply. Especially the water quality problem, people pay more and more attention to it, and the requirements are constantly improving. Galvanized steel pipe, a common pipe, will gradually withdraw from the historical stage under the influence of relevant national policies because of its corrosiveness. Plastic pipe, composite pipe and copper pipe have become common pipes in pipeline system. However, in many cases, stainless steel pipes are superior, especially thin-walled stainless steel pipes with a wall thickness of only 0.6 ~ 1.2 mm, which are safe, reliable, hygienic, environmentally friendly and economical, and are suitable for high-quality drinking water systems, hot water systems and water supply systems that put safety and hygiene first. Engineering practice at home and abroad has proved that it is one of the new energy-saving and environmental protection pipes with the best comprehensive performance in water supply system, and it is also a highly competitive water supply pipe, which will surely play an unparalleled role in improving water quality and people's living standards.

In the building water supply system, due to the glorious history of galvanized steel pipes, various new plastic pipes and composite pipes have developed rapidly, but there are still some deficiencies in various pipes, which are far from fully meeting the needs of the water supply system and the national requirements for drinking water and related water quality. Therefore, experts predict that the building water supply pipeline will eventually return to the metal pipe era. According to the application experience abroad, thin-walled stainless steel pipe is considered to be one of the metal pipes with the best comprehensive performance.

range

Thin-walled stainless steel pipes are a new family in the field of pipes. They began to be produced and used in China in the late 1990s, and have been widely used in building water supply and direct drinking water pipelines.

Thin-walled stainless steel pipes are durable and have been recognized by the engineering community. Relevant parties are starting from reducing the wall thickness and price to facilitate further promotion. Especially the small-caliber stainless steel pipe, the price is not high, so the matching connection mode, the reliability and price of the pipe fittings are the main factors that determine its development. Developers in Sichuan, Guangdong, Zhejiang, Jiangsu and other places have independently developed connection technology and pipe fittings, which are promising pipes. The Ministry of Construction and relevant departments also attach great importance to this new type of pipe. According to the document [200 1]7 1 issued by China Technology Market Management Promotion Center, Notice on Popularizing and Applying High-precision Stainless Steel Pipe and Fittings and Special Technology for Medium and High Pressure Water Supply tells us that the popularization and application of this technology and product of thin-walled stainless steel pipe is of great significance for improving the grade of modern buildings in China and improving and ensuring water quality.

At the same time, the Ministry of Construction attaches great importance to the popularization and application of thin-walled stainless steel pipes. The industry standard of thin-walled stainless steel water pipes was issued and implemented in 200 1 year. Technical specifications and installation drawings related to pipeline engineering have been issued by the Ministry of Construction and are being compiled by Tongji University. At present, Sichuan, Guangdong, Zhejiang, Jiangsu and other places have professional manufacturers to produce thin-walled stainless steel pipes, and the products are mature. So it's time to promote the application.

Good prospects at home

① There is a great demand for building water supply pipes.

According to the Ninth Five-Year Plan and the long-term target outline of 20 10, from 200 1 year to 20 10 year, the annual demand for pipelines is 500,000-600,000 kilometers, including 400,000 kilometers of hot and cold water pipelines for residential buildings. Some people think that the development of stainless steel water pipes is of great significance to improving the grade of modern urban buildings.

(2) Pipeline drinking water is developing rapidly.

With the development of national economy, piped drinking water has developed rapidly in China, such as Beijing, Shenzhen, Shanghai and Chongqing, and medium-sized cities with developed economies are actively planning to catch up. In direct drinking water, stainless steel pipes are undoubtedly second to none. At present, domestic high-end hotels and public places have installed or are installing direct drinking water pipes.

③ There are broad prospects for domestic substitute imports.

In order to popularize stainless steel pipes, China has solved the technical problem of "high diameter-wall ratio and high precision" of thin-walled stainless steel pipes from the aspects of reducing wall thickness and cost since the 1990s, which has promoted the application of stainless steel pipes and developed rapidly. If a pipeline can be widely applied, it must be localized. At present, some domestic manufacturers have the ability to produce and further develop thin-walled stainless steel pipes and fittings.

Manned mode

Stainless steel pipes can be connected in many ways. Common pipe fittings include compression type, compression type, hinged type, push type, push thread type, socket welding type, hinged flange connection, welding type and series connection mode derived from the combination of welding and traditional connection. According to different principles, these connection methods have different application scopes, but most of them are convenient to install, firm and reliable. The materials of sealing ring or gasket used for connection are mostly silicone rubber, nitrile rubber and EPDM, which meet the requirements of national standards and eliminate the worries of users.

Clamping connection step

1. Pipe breaking: cut the pipe according to the required length. When breaking the pipe, don't use too much force to avoid the pipe being out of round.

2. Burr removal: After the pipeline is cut, burr should be removed to avoid cutting the sealing ring.

3. Scribing and marking: In order to completely insert the steel pipe into the socket of the pipe fitting, the insertion length must be marked on the pipe end.

4. Assembly: The sealing ring should be correctly installed in the U-shaped groove of the pipe fitting, and the pipe should be inserted into the socket of the pipe fitting, waiting for crimping.

5. Crimping: During crimping, the convex part of the pipe fitting is placed in the groove of the die, and the jaw is perpendicular to the pipe axis.

6. Inspection: After the crimping is completed, check the crimping size with a special gauge.

Corrosion resistance of stainless steel

All metals will react with oxygen in the atmosphere and form an oxide film on the surface. Unfortunately, the iron oxide formed on ordinary carbon steel continues to be oxidized, which makes the corrosion expand and eventually forms holes. Paint or antioxidant metals (such as zinc, nickel and chromium) can be used for electroplating to ensure the surface of carbon steel, but as we all know, this protection is only a film. If the protective layer is destroyed, the steel below will begin to rust.

The corrosion resistance of stainless steel depends on chromium, but because chromium is one of the components of steel, the protection methods are different.

When the chromium content reaches 10.5%, the atmospheric corrosion resistance of steel is significantly improved, but when the chromium content is higher, the corrosion resistance is still improved, but it is not obvious. The reason is that when steel is alloyed with chromium, the types of surface oxides change, similar to those formed on pure chromium metal. This tightly attached chromium-rich oxide protects the surface from further oxidation. This kind of oxide layer is extremely thin, and the natural luster of steel surface can be seen through it, which makes stainless steel have a unique surface. Moreover, if the surface layer is damaged, the exposed steel surface will react with the atmosphere to repair itself, re-form this "passive film" and continue to play a protective role.

So all stainless steels have the same feature, that is, the chromium content is above 10.5%.

There are usually only six kinds of steel related to the application field of building construction. They all contain 17 ~ 22% chromium, and the better steel also contains nickel. Adding molybdenum can further improve the atmospheric corrosivity, especially the corrosion resistance to chlorine-containing atmosphere.

Stainless steel is resistant to atmospheric corrosion

Experience shows that the degree of atmospheric corrosion is different in different regions. For the sake of explanation, it is suggested that the regions should be divided into four categories, namely rural areas, cities, industrial areas and coastal areas.

Rural areas are basically pollution-free areas. The population density in this area is low and there are only pollution-free industries.

This city is a typical residential, commercial and light industrial area, where there is light pollution, such as traffic pollution.

Industrial areas are areas where heavy industry causes air pollution. Pollution may be caused by gases formed by fuel oil, such as oxides of sulfur and nitrogen, or other gases released by chemical plants or processing plants. Suspended particles in the air, such as dust or iron oxide precipitation produced during steel production, will also aggravate corrosion.

Coastal areas usually refer to areas within a mile from the sea. However, the ocean atmosphere can spread inland, especially on the island. The prevailing wind comes from the ocean and the climate is bad. For example, the weather in Britain is like this, so the whole country belongs to the coastal areas. If the wind is mixed with sea fog, especially because of salt deposition and accumulation caused by evaporation, coupled with less rain, it is not often washed away by rain, and the conditions in coastal areas are even more unfavorable. If there is industrial pollution, it is more corrosive.

Studies in the United States, Britain, France, Italy, Sweden and Australia have determined the influence of these areas on the atmospheric corrosion resistance of various stainless steels. The related contents are briefly introduced in the Brief Introduction of Architects published by NiIDI. The tables in this book can help designers choose the most cost-effective stainless steel for different fields.

When making a choice, it is important to determine whether there are still local factors that affect the use of the site environment. For example, when stainless steel is used under factory chimneys, near air conditioning exhaust baffles or near waste yards, abnormal situations will occur.

Maintenance and cleaning of stainless steel

Like other materials exposed to the atmosphere, stainless steel will get dirty. Future lectures will analyze the design factors that affect maintenance and cleaning costs. But rain washing, hand washing and dirty surface are still related.

The effect of rain erosion is determined by placing the same slats directly in the atmosphere and in the shed. The effect of manual cleaning is determined by manually scrubbing the right side of each lath with a sponge dipped in soapy water every six months. The results show that, compared with being placed in a shed or an unwashed place, washing with rainwater and manual scrubbing to remove dust and deposits on the surface have a good effect on the surface condition. In addition, it is also found that the surface processing conditions also have an influence, and the lath with smooth surface is better than the lath with rough surface.

Therefore, the interval of washing is influenced by many factors, and the main influencing factor is the required aesthetic standard. Although many stainless steel curtain walls are only cleaned when cleaning the glass, generally speaking, the stainless steel used for external walls is cleaned twice a year.

Typical uses of stainless steel

Most of the use requirements are to keep the original appearance of the building for a long time. When determining the type of stainless steel to be selected, the main considerations are the required aesthetic standards, the corrosiveness of the local atmosphere and the cleaning system to be adopted.

However, more and more other applications only seek structural integrity or impermeability. Such as roofs and side walls of industrial buildings. In these applications, the owner's construction cost may be more important than beauty, and the surface is not very clean.

The effect of using 430 stainless steel in dry indoor environment is quite good. However, in rural and urban areas, if you want to keep its appearance outdoors, you need to clean it frequently. In heavily polluted industrial areas and coastal areas, the surface will be very dirty and even rusty. However, in order to obtain the beautiful effect in outdoor environment, nickel-containing stainless steel must be used. Therefore, 304 stainless steel is widely used in curtain walls, side walls, roofs and other building applications, but in the industrial or marine atmosphere with severe corrosiveness, it is best to use 3 16 stainless steel.

People have fully realized the advantages of using stainless steel in structural applications. Some design standards include 304 and 3 16 stainless steel. Because "duplex" stainless steel 2205 combines good atmospheric corrosion resistance with high tensile strength and elastic ultimate strength, it is also included in European standards.

Stainless steel product shape

In fact, stainless steel is made according to all standard metal shapes and sizes, and there are many special shapes. The most commonly used products are thin plate and strip steel, and special products are also medium plate, such as hot rolled structural steel and extruded structural steel. There are also round, oval, square, rectangular and hexagonal welded or seamless steel pipes and other forms of products, including profiles, bars, wires and castings.

character of surface

As will be mentioned later, many different commercial surface treatments have been developed to meet the aesthetic requirements of architects. For example, the surface can be highly reflective or dull; Can be smooth, polished or embossed; It can be colored, colored, electroplated or etched on the surface of stainless steel to meet various requirements of designers for appearance.

It is easy to keep the surface state. Dust can only be removed by occasional cleaning. Because of its good corrosion resistance, graffiti pollution or similar other surface pollution can also be easily removed.