Underground directly buried prefabricated hot water Thermal insulation pipe
High temperature prefabricated directly buried insulation pipe not only has traditional trench and overhead laying The Conduit The incomparable advanced technology and practical performance, as well as significant social and economic benefits, are also powerful measures for heat supply and energy conservation. High temperature prefabricated directly buried insulation pipe polyurethane The hard foam insulation layer is tightly bonded to the Steel pipe The outer skin can isolate the air and water penetration, and can play a good anti-corrosion role. At the same time, its foam pores are closed, and its water absorption is very small. Polyurethane insulation pipe High density shell, polyurethane insulation pipe Glass The steel shell has good anti-corrosion, insulation and mechanical properties.
Overview of directly buried thermal insulation pipes: directly buried thermal insulation pipes can be directly buried in 0.6-1.2m frozen soil layer (so people are used to calling them directly buried thermal insulation pipes or prefabricated thermal insulation pipes), the heat loss can be reduced by more than 40% compared with ordinary pipes, the working life can be increased by more than 3-5 times compared with other thermal insulation and anti-corrosion materials, and the service life can reach 30-50 years; The quality meets or exceeds the Chinese industry standards. Its complete thermal insulation system is characterized by low overall project cost, short construction period, long service life, energy conservation, environmental protection, etc. The continuous operating temperature is 130 º C, and the peak height can reach 150 º C.
● Specification of directly buried insulation pipe DN15~DN1200
● Applicable to direct burial of fluid pipes below 130 ℃ (such as hot spring, hot water, air conditioning water, etc.)
● Meet CJ/T114-2000 and CJJ/T81-98 standards
● Professional equipment and advanced technology ensure superior quality
● Professional equipment and advanced technology ensure superior quality
● Direct burial laying and installation are convenient and fast
The directly buried insulation pipe, also known as "pipe in pipe", is composed of a "two-step method", which is composed of high-density polyethylene outer protective layer, polyurethane rigid foam plastic insulation material and steel pipes. The insulation layer is made of rigid polyurethane foam with a density of 60kg/m3 to 80kg/m3, which can fully fill the gap between the steel pipe and the casing, and has a certain bonding strength, so that the steel pipe, the outer casing and the insulation layer form a solid whole.
Composition of directly buried insulation pipe:
1. Working steel pipe: according to the requirements of transmission medium, seamed steel pipe, seamless steel pipe and double submerged arc spiral welded steel pipe can be used.
2. Insulation layer: rigid polyurethane foam.
3. Protective shell: high-density polyethylene or glass fiber reinforced plastic.
Performance of directly buried thermal insulation pipe: directly buried thermal insulation pipe has good mechanical performance and thermal insulation performance. Generally, it can withstand high temperature of 120 ℃. By modification or combination with other thermal insulation materials, it can withstand high temperature of 180 ℃. It is suitable for thermal insulation engineering of various cold and hot water high and low temperature pipelines. Future development of directly buried insulation pipe: directly buried insulation pipe has become a relatively mature advanced technology in some developed countries abroad. In recent ten years, China's heating engineering technicians are promoting the domestic pipe network laying technology to a higher level by digesting and absorbing this advanced technology.
During the design and construction of high-temperature prefabricated directly buried insulation pipes, it is necessary to understand that the direct burial laying of heating pipes can be divided into two types: compensated direct burial laying and non compensated direct burial laying, and truly master the working principles, characteristics and application occasions of the two types of laying, so as to make reasonable selection in design and safe, reliable and economical construction.
1 First of all, we should grasp the concept: the direct buried laying with compensation is to solve the thermal elongation of the pipeline through natural compensation of the pipeline and compensators (such as square and corrugated pipe compensators), so that the thermal stress is small; The uncompensated direct burial laying simply means that there is no compensation measure when the pipeline is heated, but the strength of the pipe itself is used to absorb the thermal stress.
2 Basic principle of non compensation laying method: when installing pipes, first heat the pipes to a certain temperature, then weld and fix the pipes. When the pipes return to the installation temperature (temperature decreases), the pipes bear a certain tensile stress in advance. When the pipeline works with heat, the pipeline stress is zero with the increase of temperature. When the temperature continues to rise, the pressure stress of the pipeline increases. When the temperature rises to the operating temperature, the pressure stress (thermal stress) of the pipeline is still less than the allowable stress. In this way, the pipeline can work normally without compensation device. The fourth strength theory is applied to this non compensation method, which requires preheating of the pipeline during construction, which is troublesome. However, there are a lot of engineering practices at home and abroad, and the theoretical calculation is reliable to ensure safety. The other non compensation method is that the calculation method and stress classification proposed by Beijing Gas and Thermal Design Institute in recent years adopt shakedown analysis and apply the third strength theory. This method gives full play to the plastic potential of steel, and is convenient for construction without preheating.
Underground directly buried prefabricated hot water insulation pipe
The high-temperature prefabricated directly buried insulation pipe not only has the practical performance that is incomparable with the traditional trench and overhead laying pipeline, but also has significant social and economic benefits, which is also a powerful measure for heat supply and energy conservation. The high-temperature prefabricated directly buried insulation pipe adopts the directly buried heating pipe technology, which marks that the development of China's heating pipe technology has entered a new starting point.
When the polyurethane insulation pipe is applied with the insulation layer of inner pipe and outer pipe, the foaming slurry is usually poured directly between the two pipes to form foaming at one time. Before pouring slurry insulation materials, the inner pipe and outer pipe shall be kept in good concentricity with proper tools, and the lower sealing treatment shall be tight to prevent slurry leakage. According to the flow state and foaming speed of the slurry, the insulation layer with smaller length can be poured vertically, but for most insulation layers with larger length, the inclined pouring method is used to facilitate the slurry flow and foaming. According to the formula and construction requirements, it can be injected from the upper side or the lower side. When the pipe fittings are long, the slurry output from the mixing head can be introduced into the lower part of the pipe gap through the conduit, and the conduit will be gradually drawn out with the increase of injection amount.
The polyethylene jacket is made of high-density polyethylene material, which has high mechanical strength and excellent corrosion resistance. It can ensure that the pipes will not be damaged by external factors during transportation, installation and use.
The inner surface of the polyethylene outer protective layer is corona treated by the low-temperature plasma generated by electrode discharge. After corona treatment, the inner surface tension of the outer protective tube reaches more than 50 dynes/cm, which significantly increases the shear strength between the insulation layer foam and the outer protective tube. It is of great significance to ensure the quality of the integral pipe and extend its service life.
Advantages of polyurethane insulation pipe: the on-site joint insulation of insulation pipe can be carried out only after the pressure test is qualified. The insulation layer has two methods: on-site foaming construction and insulation tile construction. No matter which method is used for construction, there is no annular space, crack, delamination and other defects. There are many methods of protective layer (such as high-density polyethylene and glass fiber reinforced plastic protective layer), However, the integrity, tightness and waterproof of the joint must be guaranteed. Insulation pipe Pan Huailiang, because the polyurethane rigid foam prefabricated directly buried insulation pipe foam insulation layer is closely bonded to the steel pipe skin, which can isolate the infiltration of air and water, and can play a good anti-corrosion role.
At the same time, its foam pores are closed, and its water absorption is very small. High density polyethylene shell and glass fiber reinforced plastic shell have good anti-corrosion, insulation and mechanical properties. Therefore, the outer skin of working steel pipe is difficult to be eroded by external air and water. As long as the water quality inside the pipeline is well treated, the weld length increases by 30 compared with the straight seam pipe of the same length. This product is widely used in flammable and non flammable fluid transmission pipelines, boilers and steel structures.
Seamless steel pipe is also called hot-rolled seamless steel pipe or hot-rolled steel pipe. The insulation layer is made of high-temperature fiber felt and spiral welded pipe, whose strength is generally higher than that of straight seam welded pipe. It can produce welded pipe with larger pipe diameter with narrower billet, and can also produce welded pipe with different pipe diameter with the same width of billet. Seamless steel pipe production process seamless steel pipe is important to complete the stretch reducing process through stretch reducing is the continuous rolling process of hollow base metal without mandrel.
The super steel sheathed steel directly buried insulation pipe is composed of internal working steel pipe, external protective steel pipe and intermediate insulation layer. The working steel pipe is sandblasted and coated with two layers of anti rust paint. Hot rolled seamless steel pipe of prefabricated directly buried thermal insulation pipe is resistant to high temperature and pressure, suitable for medium temperature of 350 ℃, strong pressure corrosion resistance, high strength of anti-corrosion coating, and it is not easy to damage seamless elbow elbow, which is a kind of pipe fitting used for pipe turning.
The proportion of all fittings used in the piping system is approximately. Generally, different forming processes are selected for elbows with different materials or wall thicknesses. The commonly used seamless elbow forming processes of manufacturers include hot pushing, stamping, extrusion, etc.
Buildings with directly buried insulation pipes can be divided into civil buildings with directly buried insulation pipes and non civil buildings with directly buried insulation pipes according to the nature and function of their use. Buildings using directly buried thermal insulation pipes for non civil use can also be called productive buildings using directly buried thermal insulation pipes. It refers to buildings using directly buried thermal insulation pipes for means of production and serving industrial and agricultural production. Buildings using directly buried thermal insulation pipes for civil use can also be divided into residential buildings using directly buried thermal insulation pipes and public buildings using directly buried thermal insulation pipes according to their use functions. Buildings with directly buried thermal insulation pipes for living refer to buildings with directly buried thermal insulation pipes for people's daily life. Buildings with directly buried thermal insulation pipes for public use refer to buildings with directly buried thermal insulation pipes for people's various social activities.
Application of polyurethane insulation pipe: polyurethane insulation pipe is used for insulation and cold insulation of indoor and outdoor pipelines, central heating pipelines, central air-conditioning pipelines, chemical, pharmaceutical and other industrial pipelines. The polyurethane foam insulation pipe has been developed rapidly as an excellent thermal insulation material since the polyurethane synthetic material was born in the 1930s, and its application scope is also becoming more and more extensive. Because of its simple construction, energy-saving and anti-corrosion, it is widely used in various kinds of heat supply, refrigeration, oil transmission, steam transmission and other pipelines.
Steel pipe: according to the requirements of the design and customers, seamless pipe (GB8163-87) shall be used below DN200, spiral welded pipe (GB9711-88; SY/T5038-92) and straight seam welded pipe (GB3092-93) shall be used above DN200. After the steel pipe surface is treated by advanced shot blasting, the steel pipe rust removal grade can reach Sa2 in GB8923-1988 standard, and the surface roughness can reach R=12.5 μ m in GB6060.5-88 standard.
Insulation layer: the product is applied outside the steel pipe by on-site pouring or prefabrication, which is simple and effective. The suitable temperature of polyurethane insulation layer is 120 ℃ - 196 ℃. The thermal conductivity of polyurethane foam is low in thermal insulation materials, so the heat loss of materials can be reduced to a low limit.
High density polyethylene: the product is characterized by high strength, impact resistance, environmental aging resistance, prestressed cracking, corrosion resistance, low temperature resistance, easy welding, simple construction, strict sealing and no leakage.
