Substitution of spiral submerged arc welded pipe for traditional pipe is a new trend of development

 The historical experience of the countries all over the world in the process of modernization of spiral submerged arc welded pipes shows that the development speed of plastic pipes exceeds the economic development speed of the same period. It is an irresistible trend of historical development to replace traditional pipes with plastic pipes. Even in developed countries where dense plastic pipe networks have been built, the application of plastic pipes is still increasing year by year. For example, in 1986, the total consumption of plastic pipes in Europe was 2.134 million tons, in 1998 it increased to 3.465 million tons, with an average annual growth rate of 5.2%, exceeding the growth rate of national economy in the same period. In the past 10 years, the average annual growth rate of China's plastic pipe market was 20%. In 2000, 2002 and 2003, the output reached 700,000-800,000 t, 1.3 million T and 1.5 million t, respectively, with a growth rate of 15%. Among them, 55% were PVC pipes and 40% were PE pipes. It is expected that the annual growth rate of plastic pipes in China will still exceed 20% by 2010.

Advantages of Plastic Pipes

Plastic buried pipes have been widely used in foreign countries. The reason is that buried pipes have many advantages over cast iron pipes, steel pipes, cement pipes and other traditional buried pipes.

Strength and Rigidity

On the surface, the strength and rigidity of plastic buried pipes are inferior to those of cement pipes, especially reinforced concrete pipes. In fact, plastic buried pipes belong to flexible pipes. Under the correct design and construction conditions, plastic buried pipes and surrounding soil bear the load together. Therefore, plastic buried pipes do not need to achieve the same strength and rigidity as concrete pipes and other "rigid pipes", so they can meet the burial requirements. Mechanical properties in use.

Hydraulic characteristics of plastic pipes are smooth, small resistance and large water flux. Under the same caliber, the water flow of plastic pipes is larger than that of concrete pipes. When the terrain is sloping, the diameter of plastic pipes can be reduced and the construction quantity is small.

Tightness

The sealing property of mud pipe is very poor. The domestic flat joint concrete pipe is sealed only by plastering a circle of concrete. It is difficult to ensure no leakage during construction. In addition, the rigid pipe of concrete pipe system can cause damage to the joint if it moves slightly (such as uneven settlement of soil). In addition, the cement pipe is sealed by vulcanized rubber ring, and the plastic pipe is sealed by thermoplastic elastomer ring. The former is used. The service life is shorter than that of the latter, and the connection and sealing of plastic pipes have a series of strict requirements, which can maximize the assurance of no leakage. The life of cement pipe is only 15 years, while that of plastic pipe is 50 to 100 years. Domestic sewage and rainwater are usually corrosive. Industrial sewage is more corrosive. Metal and cement underground drainage pipes are used to transport sewage. Their corrosion resistance is worse than that of plastic pipes. In some areas, the corrosiveness of outdoor natural environment is very large. For example, in Tanggu New District of Tianjin, the cement sewage pipes laid can not be found after three years. All of them are corroded by salt in sea water, so plastic pipes have to be laid twice.

Laying construction

Plastic pipes are light in weight, long in length, few joints, low requirement for pipe trench, convenient in connection, fast in construction and low in construction cost. They have more outstanding advantages in urban and harsh natural conditions.

Comprehensive Economy

In terms of comprehensive economy, the advantages of plastic pipes are being recognized by more and more users. Although the unit price of plastic pipe is slightly higher than that of cement pipe, the total cost of engineering is not higher than that of cement pipe. Tianjin Municipal Engineering Design Institute has systematically studied the application of UPVC double-wall corrugated pipe since 1992 and PE double-wall corrugated pipe in buried drainage pipe since 1998. The conclusion is that the cost of double-wall corrugated pipe is equivalent to that of concrete flat-mouth pipe, 30% lower than that of socket concrete pipe. The construction period is significantly shortened and the economic benefit is remarkable.