High-density polyethylene (HDPE) double-wall corrugated pipe is a new type of pipe with an annular outer wall and a smooth inner wall. It was first successfully developed in Germany in the early 1980s. After more than ten years of development and improvement, it has developed from a single variety to a complete product series. It is very mature in production technology and application technology. Due to its excellent performance and relatively economical cost, it has been greatly promoted and applied in developed countries such as Europe and the United States. In my country, the promotion and application of HDPE double-wall corrugated pipes are in an upward trend, and all technical indicators have reached the use standards. The inner wall of the double-wall corrugated pipe is usually blue and black, and some brands use yellow inner walls.
Process characteristics
·Digital centralized control of the entire line ·Dual machine co-extrusion, double-layer diversion
Full vacuum belt feeding
Random expansion one-step forming HDPE double wall corrugated pipe product specifications
Specifications:
DN110mm, DN125, DN150, DN220, DN225mm, DN250, DN300mm, DN400mm, DN500mm, DN600mm, DN700mm, DN800, DN1000, DN1200 and other specifications
Advantages of double wall corrugated pipe
Reasonable structure and beautiful appearance
Temperature resistance -40℃-60℃
Small resistance, large flow
·Strong flame retardancy ·Long service life
Reliable hygienic performance
·Low overall cost·Acid and alkali resistant and corrosion resistant
·High strength and strong earthquake resistance
Energy saving and consumption reduction
Easy to install and transport
Features:
High-density polyethylene (HDPE) has excellent chemical stability, aging resistance and environmental stress cracking resistance. The HDPE double-wall corrugated pipe produced from it as raw material is a flexible pipe. Its main properties are as follows:
Strong resistance to external pressure
The outer wall has an annular corrugated structure, which greatly enhances the ring stiffness of the pipe, thereby enhancing the pipe's resistance to soil load. In this performance, HDPE double-wall corrugated pipe has obvious advantages compared with other pipes.
Low project cost
Under the same load conditions, HDPE double-wall corrugated pipes only need thinner walls to meet the requirements. Therefore, compared with solid wall pipes of the same material specifications, it can save about half of the raw materials, so the cost of HDPE double-wall corrugated pipes is also lower. This is another outstanding feature of this pipe.
Easy construction
Because HDPE double-wall corrugated pipe is light in weight, easy to carry and connect, it is quick to construct and simple to maintain.
Under poor conditions, its advantages are more obvious.
Small friction coefficient and large flow rate
HDPE double-wall corrugated pipes made of HDPE can pass a larger flow rate than other pipes of the same diameter. In other words, under the same flow requirements, HDPE double-wall corrugated pipes with a relatively smaller diameter can be used.
Low temperature resistance and impact resistance
The brittle temperature of HDPE double-wall corrugated pipe is -70℃. No special protective measures are required during construction under normal low temperature conditions (above -30℃), which makes construction convenient in winter. In addition, HDPE double-wall corrugated pipe has good impact resistance.
Good chemical stability
Since HDPE molecules have no polarity, they have excellent chemical stability. Except for a few strong oxidants, most chemical media will not damage them. The soil, electricity, acid and alkali factors in the general use environment will not damage the pipe, will not breed bacteria, will not scale, and its flow area will not decrease with the increase of operating time.
Long service life
Under the condition of not being exposed to sunlight ultraviolet rays, the service life of HDPE double-wall corrugated pipe can reach more than 50 years.
Excellent wear resistance
Germany has used experiments to prove that the wear resistance of HDPE is even several times higher than that of steel pipes.
Proper flexure
A certain length of HDPE double-wall corrugated pipe can be slightly bent axially and is not affected by a certain degree of uneven settlement of the ground. It can be laid directly in a slightly crooked groove without pipe fittings, etc.
Engineering solution:
Be familiar with the design drawings and materials, and understand the pipeline layout, direction, process flow and construction and installation requirements of the main and branch pipes.
Be familiar with the site conditions and understand the distribution of existing plane and elevation control points along the designed pipeline.
According to the pipeline plane and existing control points, and combined with the actual terrain, organize the measured data and draw a measured sketch.
After entering the site, the leveling points and guide points handed over by the construction unit are re-surveyed. After the closing error meets the design requirements, the guide points and leveling points are encrypted. There is a leveling point within every 60 meters, and the encrypted points must be closed and adjusted. The closing error of the leveling points is 20√L to ensure the accuracy of the encrypted points to meet the accuracy of the drainage pipe elevation and linear control.
Since the centerline piles of the pipeline will be dug out during construction, construction control piles should be measured and installed in places that are not disturbed by construction and are convenient for measurement and easy to protect. The extension line or guide wire method should be used to measure and install centerline direction control piles, and the intersection method or parallel line method should be used to measure and install ancillary structure position control piles.
The measurement during the construction process is mainly to determine the elevation of the trench bottom. After mechanical excavation, follow-up measurement is adopted to prevent over-excavation and ensure that the trench bottom elevation meets the design requirements. After the pipeline is installed, re-measurement is carried out to deal with problems in a timely manner so that the pipe bottom elevation is controlled within the allowable deviation range. Before the measurement work starts every day, adjacent level re-measurement is carried out.
The center of the pipeline is determined by the centerline control piles. The control piles are used to drive the edge lines on the pipeline foundation to determine the laying position of the pipeline.
The elevation of the well chamber is controlled according to the design requirements. After the pipeline is laid, the completion review measurement of the pipe top and structure shall be carried out.
Trench excavation and foundation treatment:
Be familiar with the drawings, measure, locate and lay out according to the given leveling points and coordinate control points in the design, introduce temporary leveling points and control piles, and trench excavation can only be carried out after review and certification approval by the supervising engineer.
The project uses excavators for excavation. The trench excavation depth and pipeline centerline must be strictly controlled. A 20cm margin is left for mechanical excavation. The trench is cleared manually to the designed trench bottom elevation, and mileage piles are led to the trench bottom.
Strictly control the slope coefficient of trench excavation, and dig to a sufficient width according to the designed slope coefficient. Pay attention to the soil conditions of the trench during excavation. If necessary, ask the resident supervisor, Party A, and design representative to determine the slope coefficient on site to prevent trench edge collapse.
The earth excavated from the trench is directly loaded onto trucks for transportation, and the transportation location is designated by the owner.
When encountering groundwater during trench excavation, drainage ditches and sump pits shall be set up to timely drain and dewater the groundwater in the trench, and measures shall be taken to reinforce the foundation by first laying pebbles or crushed stone layers (thickness not less than 100mm); when there is no groundwater, the soil under the foundation shall be compacted, and the compaction coefficient shall be greater than 0.95; when encountering soft foundations such as silt and miscellaneous fill, graded Gobi soil shall be used for replacement filling according to the pipeline treatment requirements; the replacement filling thickness is 30cm.
After the trench is excavated for about 100 meters, the earthwork is transported out and the trench is cleared manually, and it is inspected and approved by the supervising engineer, the next construction process can be carried out in the trench.
drain:
HDPE double-wall corrugated pipe for drainage is a new type of pipe made of polyethylene resin as the main raw material, with appropriate amount of additives added, and extruded and molded. It is suitable for outdoor drainage of buildings and municipal sewage. It has the advantages of light weight, small drainage resistance, high compressive strength, corrosion resistance, and convenient construction. It is an ideal material to replace cast iron pipes and cement concrete pipes.
HDPE structural wall pipe has more economic and social benefits than cement bell-and-spigot pipe
1. Greatly shorten the construction period and reduce the construction difficulty
Since HDPE double-wall corrugated pipes are much lighter than cement pipes and are very easy to socket, the construction difficulty is greatly reduced; and the shortest HDPE double-wall corrugated pipe is 6 meters, while the cement pipe is 2.5 meters, which greatly shortens the construction period.
2. HDPE double-wall corrugated pipe has low requirements on the bottom of the trench
Since cement pipes are rigid pipes, in order to ensure the socket effect, the bottom of the trench must be smooth, it is best to lay a foundation layer, and the construction workers are required to have an absolute sense of responsibility. HDPE double-wall corrugated pipes are flexible pipes and do not have high requirements for the bottom of the trench.
3. HDPE pipes will not break due to ground subsidence or crustal changes
The elongation of HDPE pipe is more than 20 times that of steel pipe and six and a half times that of PVC, but its elongation at break is very high and its ductility is very strong. This means that when the ground sinks or the earth's crust changes during an earthquake, the HDPE pipe can resist deformation without breaking. This is far better than steel pipes and PVC pipes with obvious brittleness. This performance has been proven at home and abroad (the Great Hanshin Earthquake in Japan did not cause the pipe to break; the HDPE pipe was not damaged in the Zhinan Baoshan Earthquake).
4. The permeability of HDPE pipes is much lower than that of cement pipes, less than 2%, and will not cause secondary pollution to groundwater
Cement pipes are inelastic and although they are equipped with rubber rings, the sealing effect is poor. In particular, since cement pipes are heavy and difficult to construct, construction workers simply ignore the effect of the socket, causing the rubber ring to lose its function, thereby increasing the permeability of the pipe.
5. HDPE pipe has a long service life of more than 50 years
The safe service life of PE pipes is more than 50 years, which has been proven not only by international standards and the new international, but also by advanced countries. The theoretical service life of cement pipes is 20 years, but as silicates, they are corroded by acids and alkalis for a long time, and their service life is greatly reduced. There are examples all over the country where cement pipes have to be replaced within a few years due to sewage leakage, ground subsidence, and joint fractures.
6. The inner surface of HDPE pipe is smooth, without positive and negative charges, and does not scale.
Cement pipes are prone to scaling, which reduces the pipe diameter and affects the flow rate.
7. HDPE is light, easy to transport and install, and has no loss
Cement pipes are heavy, inconvenient to transport and install, and are easily damaged during transportation and installation.
8. When the flow rate, slope and burial depth of the pipeline are the same, HDPE can be one or two sizes smaller than cement pipe
The roughness coefficient of the inner surface of HDPE is 0.009, and the roughness coefficient of the inner surface of cement pipe is 0.014. According to the world-recognized Xie Cai law, for the same flow calculation, HDPE pipe can be two sizes smaller than cement pipe. In actual applications, it is recommended to use one size smaller. For example, a cement pipe designed for 600 diameter can be replaced with a 500 diameter HDPE.
Applications:
It is mainly used in large-scale water transmission, water supply, drainage, sewage discharge, exhaust, subway ventilation, mine ventilation, farmland irrigation, etc. with working pressure below 0.6MPa.
1. Municipal engineering: used as drainage and sewage pipes.
2. Construction projects: used as rainwater pipes, underground drainage pipes, sewage pipes, and ventilation pipes in buildings.
3. Railway and highway communication equipment: used as protection tube for communication cables and optical cables.
4. Industry: Widely used in sewage pipes in chemical, hospital, environmental protection and other industries.
5. Agricultural garden engineering: used for drainage in farmland, fruit and tea gardens, and forest belts.
6. Road engineering: used as seepage and drainage pipes for railways and highways.
7. Mines: used as mine ventilation, air supply and drainage pipes.
8. Double-wall corrugated pipe with holes: can be used as seepage and drainage pipes for highways in saline-alkali land.
9. Golf course and football field projects: used as seepage and drainage pipes for golf courses and football fields.
