Generally speaking, type B HDPE winding structure wall reinforced pipe (also call HDPE carat pipe) and HDPE double-wall corrugated pipe are similar in length, color, and appearance. It's hard to tell the difference at first glance. Now we enumerate the differences between these two kinds of pipes in detail, which will be of great help in distinguishing the two kinds of pipes.
HDPE winding structure wall reinforced pipe B Type (referred to as HDPE carat pipe)
Adopt standard: Type B structural wall pipe specified in GB/T19472.2-2004;
Connection method: Spiral wound pipe with socket type electrofusion connection method.
HDPE double-wall corrugated pipe (referred to as corrugated pipe)
Adopt standard: Type B structural wall pipe specified in GB/T19472.1-2004;
Connection method: Tight-force socket type packing connection.
Carat Pipe VS Double-wall Corrugated Pipe
1. Comparison of raw materials
The carat pipe of the same pipe diameter is more than 60% heavier than the corrugated pipe. In order to ensure the flexibility of its quality and the good welding performance of the interface, 100% new raw materials must be used, so the quality of the produced pipe is reliable and stable.
The corrugated pipe extrusion process is simple, the relatively layered double-walled pipe structure, the pipe loses its flexibility; and the addition of recycled materials often exceeds 70% during production, which increases the instability and fragility of the pipe quality, and changes the flexibility of the pipe. And the mass flow rate of the melt, the appearance of the pipe is not smooth, and the ring stiffness and the tensile strength of the weld are reduced, and it is easy to cause broken pipes and cracks in areas with uneven geological settlement.
Since the recycled material added in the production process of this pipe is much larger than the polyethylene material, it will appear on the market and you can buy this pipe at a very low price.
2. Comparison of production technology
The carat tube is computer-controlled hot winding and rolling cooling by natural wind. The structure wall has no internal stress, no welding seam, and the wall thickness of the pipe is uniform. The large-diameter pipes produced by winding molding mainly have specifications of DN300mm-DN2000mm, which are reinforced by spiral ribbed pipes, which greatly increase the ring stiffness of the pipe. The ring stiffness exceeds 20 KN/m2, and the ring stiffness can be continuously adjusted according to engineering requirements, and the maximum buried depth can reach 20m.
The corrugated pipe is a pipe formed by directly extruding two concentric pipe embryos and forming by blister. It belongs to the extrusion molding process. Since the caliber of the extruded tube is proportional to the die of the equipment when it reaches a certain caliber, the development of the equipment becomes a technical problem and increases the production cost. Therefore, the caliber of the produced pipe is smaller, and the main production is pipes below DN600mm.
In addition, due to the poor double-wall composite degree of the corrugated pipe, the inner and outer walls are prone to delamination when compressed, and the outer rib-shaped wall is thin, the force bearing capacity is poor, and the sag occurs when pressed, so the ring stiffness is low, and the diameter is low. The larger the size, the lower the safety. Although there are a few domestic manufacturers that can produce pipes below DN1200mm, there are not many practical application cases.
3. Comparison of ring stiffness
All special-shaped pipes adopt the method of adjusting the moment of inertia (the distance between the center of gravity of the pipe structure wall and the top of the outer diameter of the pipe) to improve the stiffness of the adjusting ring. The two-layer main PR type, the maximum moment of inertia can reach 19.8cm, and the SQ type can have more than four layers, and its moment of inertia ≥2*19.8cm), so the stiffness of the pipe ring of all diameters is high, which can exceed the national standard GB/ The maximum SN16 specified in the T19472.2-2004 standard (≥16KN/㎡).
The ring stiffness of bellows below DN600 can only reach S2 level (S2≥8KN/㎡), and the ring stiffness above DN800 can only reach S1 level (S1≥4KN/㎡).
4. Comparison of connection methods
The connection method adopted by the carat tube is: socket type electrofusion connection. One end of this pipe is a socket with an embedded electric fuse, and the other end is a flat-wall socket. During construction, you only need to put the socket into the socket for electrofusion. When the wire is connected to electricity, it is melted into one body, and the whole pipeline of dozens of kilometers long is like a whole pipe.
Socket type electrofusion connection has the following advantages:
a. The socket is completely fused, and the stiffness and strength of the interface are consistent with the pipe body, which belongs to the body connection. When the pipeline is deformed by force, the deformation will be smoothly distributed to the entire pipe through the joint without stress concentration at the joint. In areas with complex geological conditions such as soft foundations or tidal flats, the foundation often undergoes uneven settlement. The carat pipe connected by socket-type electric fusion is like a whole pipe, giving full play to the characteristics of sealing and flexibility, and adapting to geological changes. In geologically unstable areas, where frequent heavy loads are used for buried laying, the carat tube with socket type electrofusion connection has strong impact resistance. This is unthinkable for bellows.
b. Carat pipes with socket-type electric fusion connection can really make the construction fast, and when there is groundwater and the drainage of precipitation is difficult, the area that is easy to collapse, and the long-term excavation will affect the safety of traffic, buildings and personnel, adopt the bearing The HDPE carat pipe with plug-in electrofusion connection can be backfilled while digging and laying the pipe. Since the interface is the main body connection, the ability to resist stress is strong. After the pipe is welded on the edge of the groove, the entire pipe can be put into the groove as a whole. In addition to the strict backfill density required for other plastic pipes, the The flatness of the trench, the width of trench excavation, and the lower requirements for grading, etc., reduce the amount of excavation and the amount of earth moved out of the site.
However, the corrugated pipe should not only pay attention to the flatness of the groove, increase the amount of work, but also use sealing ring connection. This connection uses materials other than polyethylene, so that in the case of a large temperature difference in the piping system, the joint is due to the expansion coefficient The difference may cause water leakage or plastic deformation, which will affect the flow capacity and tightness of the piping system. Under normal circumstances, the anti-aging ability and long life of polyethylene materials are undeniable, but because the existing bellows joints all use rubber sealing rings, the anti-aging ability and life of rubber materials are far lower than that of polyethylene materials. Moreover, the rubber material is not resistant to corrosion and easy to age. After aging, it becomes hardened and inelastic or the rubber ring is eroded (the best seal ring in the world has only 15 years of life), so it will greatly reduce the operating quality of the polyethylene pipe system and the polyethylene pipe The life of the system.
5. Comparison of maintenance and service life
The main material (high-density polyethylene) used in the carat tube has a life of more than 50 years, and the connection adopts a socket type electrofusion connection (ie, the body connection) without auxiliary materials, so the pipeline system has a life of more than 50 years.
Corrugated pipe connection requires auxiliary materials, so the life of the piping system is affected by the life of auxiliary materials (such as rubber seals, etc.) (plus the addition of recycled materials during the production process, generally less than 15 years), the piping system needs to be maintained and it is difficult to maintain .
Through the comparison of HDPE carat pipe and double-wall corrugated pipe, it can be concluded that carat pipe is much higher than corrugated pipe in terms of weight, quality and overall performance.
HDPE carat pipe has been widely used in foreign countries, and is now evaluated as a key promotion product by the Ministry of Construction in China. In the field of municipal power terminal chemical industry in coastal areas, a large number of pipes of DN2200 and below are used. At present, HDPE winding reinforced pipe has been successfully used in important national projects and industries such as petrochemical, petroleum, nuclear power, aluminum metallurgy, etc., as the only new material drainage pipe.